Heat erasable neutral ink and preparation method thereof

Abstract

The invention discloses thermal erasable neutral ink and a preparation method thereof. The hot erasable neutral ink comprises temperature change pigment color paste and a thickening agent, the thickening agent is modified xanthan gum, and the modified xanthan gum comprises a benzotriazole group. According to the hot erasable gel ink, the modified xanthan gum is adopted as a thickening agent, and the modified xanthan gum contains a benzotriazole group, so that the anti-ultraviolet performance of the ink can be improved, a color former in temperature change pigment color paste is prevented from being degraded, and color fading of the ink and handwriting is avoided. Meanwhile, according to the formula of the ink, an existing thickening system is modified, and modified xanthan gum containing benzotriazole groups is synthesized, so that the application performance of the hot erasable gel ink is improved, and the effects of reducing cost and improving efficiency are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of gel ink, in particular to a thermally erasable gel ink and a preparation method thereof. Background Art

[0002] Neutral ink is the most widely used learning and office tool, but it cannot be modified directly after writing. The original handwriting must be covered with correction fluid or correction tape to modify it. In order to solve the erasability problem of neutral pens, thermal inks have been developed on the market. Its basic principle is mainly based on the changes of various components of thermal materials at different temperatures to achieve color development and color elimination. Thermal materials are mainly composed of colorants, color developers, color change temperature adjusters, and polymer wall materials. When writing at room temperature, thermal color-changing pigments and color developers combine to generate colors. When using an eraser or a hot eraser to rub the handwriting, the temperature of the paper surface rises instantly, the colorants and color developers are disconnected, the color disappears, and the handwriting looks like it has been erased. The user can rewrite at the erased place. Compared with traditional correction fluids, the ink of thermal erasable ink pens has no odor and is more environmentally friendly. At the same time, the disadvantages of thermal erasability are relatively prominent. Compared with conventional water pens, the color of thermal erasable ink pens may be lighter, and may not appear bright enough when compared. One of the most important disadvantages is that the storage stability of thermal erasable ink is greatly affected by the environment.

[0003] The color development and elimination of heat-erasable color paste is achieved through electron transfer between the color developer and the color former. The color former is generally spiropyran, fluorane, and triarylmethane compounds. Such heterocyclic compounds are easily affected by high-energy ultraviolet rays, which leads to the failure of some color pastes. The cost of adding anti-ultraviolet agents to the ink formula is too high and not suitable for commercial promotion. Therefore, promoting a heat-erasable ink with high cost performance and anti-ultraviolet performance has become a research topic in the pen industry. Summary of the invention

[0004] In order to improve the light resistance performance of heat-erasable neutral ink, the present invention provides a heat-erasable neutral ink and a preparation method thereof.

[0005] The invention provides a heat-erasable neutral ink, comprising a temperature-variable pigment paste and a thickener; the thickener is modified xanthan gum, and the modified xanthan gum comprises a benzotriazole group.

[0006] According to one embodiment of the present invention, the molar content of the benzotriazole group in the modified xanthan gum is 0.02-0.024 mol / g.

[0007] According to another embodiment of the present invention, the heat-erasable neutral ink includes, by weight percentage: 20-40% of the temperature-changing pigment paste, 0.25-0.35% of the thickener, 5-15% of the moisturizer, 1-5% of the wetting dispersant, 0.2-1% of the lubricant, 0.2-0.5% of the preservative and mildew preventer, 0.2-0.5% of the rust inhibitor, 0.2-1% of the pH adjuster, and the balance is deionized water.

[0008] According to another embodiment of the present invention, the temperature-changing pigment paste is a dispersed temperature-changing pigment paste.

[0009] According to another embodiment of the present invention, the moisturizing agent is selected from one or more of glycerol, polyethylene glycol, β-glucan, glyceryl polyether-26, glyceryl polyether-7, propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, sorbitol, sorbitol polyether-6, sorbitol polyether-40, maltitol, lactose and sorbitol; and / or the wetting and dispersing agent is selected from one or more of non-ionic wetting and dispersing agents or weak anionic polymer high-efficiency wetting and dispersing agents; and / or the lubricant is selected from one or more of oil-soluble phosphate esters, polyvinyl pyrrolidone, oleic acid, potassium oleate, oleic acid soap, triethyl phosphate, high molecular weight polydimethylsiloxane, potassium linoleate, sodium oleate and sodium ricinoleate; and / or the preservative and mildew preventive is selected from phenoxyethanol, iodopropynyl butyl carbamate, KathonLXE, Proxel One or more of XL2, Rocima623 and polyquaternary ammonium salt; and / or the rust inhibitor is selected from one or more of benzotriazole octylbenzotriazole, dodecylbenzotriazole, N,N-bis(benzotriazole methylene) laurylamine and toluenetriazole and naphthyltriazole; and / or the pH regulator is selected from one or more of 2-amino-2-methyl-1-propanol, sodium hydroxide, triethanolamine and ammonia water.

[0010] The present invention also provides a method for preparing the heat-erasable neutral ink, comprising: S1, adding the thickener into deionized water and dispersing it evenly; S2, adding other components while stirring to obtain the heat-erasable neutral ink.

[0011] According to one embodiment of the present invention, the order of adding the other components in the step S2 is the moisturizer, the wetting and dispersing agent, the lubricant, the bactericide, the rust inhibitor, the pH regulator, and the temperature-variable pigment paste.

[0012] The present invention discloses a heat-erasable neutral ink and a preparation method thereof. The heat-erasable neutral ink comprises a temperature-dependent pigment paste and a thickener; the thickener is a modified xanthan gum, and the modified xanthan gum comprises a benzotriazole group. The heat-erasable neutral ink of the present invention adopts modified xanthan gum as a thickener, and the modified xanthan gum comprises a benzotriazole group, which can improve the anti-ultraviolet performance of the ink, prevent the degradation of the colorant in the temperature-dependent pigment paste, and avoid the fading of the ink and handwriting. At the same time, the ink formula of the present invention selects to modify the existing thickening system, and by synthesizing xanthan gum modified with a benzotriazole group, the application performance of the heat-erasable neutral ink is improved, thereby achieving the effect of reducing costs and increasing efficiency. DETAILED DESCRIPTION

[0013] The present invention is described in detail below in conjunction with specific implementation modes.

[0014] The heat-erasable neutral ink of the present invention comprises a temperature-variable pigment paste and a thickener. The thickener is a modified xanthan gum, and the modified xanthan gum comprises a benzotriazole group. The thickener in the heat-erasable neutral ink of the present invention is a modified xanthan gum. Xanthan gum has good water solubility and thixotropy, can effectively improve the viscosity of the ink, is not easily affected by other components in the ink, and the viscosity will not change significantly after long-term storage. It has multifunctional groups and provides the possibility for modification. The heat-erasable neutral ink of the present invention adopts a benzotriazole group-modified xanthan gum, wherein the benzotriazole group can improve the anti-ultraviolet performance of the xanthan gum, thereby improving the anti-ultraviolet performance of the ink, and can avoid the fading of the ink and handwriting caused by the degradation of the coloring agent in the ink. The present invention adopts a benzotriazole group-modified xanthan gum to significantly reduce the cost compared to adding an anti-ultraviolet agent, and does not affect other properties of the heat-erasable neutral ink.

[0015] In an optional embodiment, the molar content of the benzotriazole group in the modified xanthan gum can be 0.02-0.024 mol / g. In the heat-erasable neutral ink, it plays a role in the degradation of the colorant by ultraviolet rays, so the molar content of the benzotriazole group in the modified xanthan gum can be reasonably selected according to factors such as the amount of the thickener in the ink, the content of the colorant, and the type of the colorant. Generally speaking, the molar content of the benzotriazole group in the modified xanthan gum is within the above range.

[0016] The modified xanthan gum adopted in the heat-erasable neutral ink of the present invention can be obtained by the compound with benzotriazole group and double bond that can produce free radical reaction and xanthan gum reaction.For example, but not limited to, the preparation method of modified xanthan gum comprises: xanthan gum (1g) is dissolved in 150mL distilled water at room temperature for 60 minutes under constant temperature stirring.Then, 2-(2'-hydroxy-4'-acryloyl-6'-methyl)-benzotriazole (15g) is joined in the xanthan gum solution and stirred for 30 minutes, pass N2 to remove dissolved oxygen, when temperature reaches 70 ℃, add 0.3g hydrogen peroxide, add ethanol / water mixture (4:1, v / v) under high-speed stirring after reaction for 4 hours, then soak 24 hours with ethanol / water mixture (4:1, v / v), filter and collect the modified xanthan gum.

[0017] 2-(2′-hydroxy-4′-acryloyl-6′-methyl)-benzotriazole can be prepared by nitroamination of o-nitroaniline followed by diazotization, coupling of the diazo compound with 3,5-dihydroxytoluene and then addition of a reducing agent for reduction cyclization to obtain benzotriazole phenol, and the benzotriazole phenol is prepared by reaction with acryloyl chloride.

[0018] Of course, the modified xanthan gum used in the present invention can also be synthesized by other methods.

[0019] In an optional embodiment, the heat-erasable neutral ink comprises, by weight percentage: 20-40% of temperature-variable pigment paste, 0.25-0.35% of thickener, 5-15% of moisturizer, 1-5% of wetting dispersant, 0.2-1% of lubricant, 0.2-0.5% of antiseptic and mildew preventive, 0.2-0.5% of rust preventive, 0.2-1% of pH regulator, and the balance of deionized water. The weight percentage of all components in the heat-erasable neutral ink of the present invention is 100%.

[0020] The temperature-changing pigment paste in the heat-erasable neutral ink can be a dispersed temperature-changing pigment paste. Specifically, the temperature-changing pigment paste can be a conventional commercially available paste or a configured paste.

[0021] The humectant in the heat-erasable neutral ink is beneficial to increase the time of removing the cap from the pen core, improve the high-temperature storage stability, and avoid the phenomenon of ink accumulation during writing. The humectant of the heat-erasable neutral ink of the present invention can be selected from one or more of glycerol, polyethylene glycol, β-glucan, glycerol polyether-26, glycerol polyether-7, propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, sorbitol, sorbitol polyether-6, sorbitol polyether-40, maltitol, lactose and sorbitol.

[0022] The wetting and dispersing agent in the ink can adjust the surface tension of the ink. If the surface tension is too high, the ink will penetrate slowly into the paper and will not dry easily. If the surface tension is too low, the ink will blur and the erasability will be poor. When writing, the ink will easily hang on the inner wall of the pen core, affecting the appearance. The wetting and dispersing agent of the heat-erasable neutral ink of the present invention can be selected from one or more non-ionic wetting and dispersing agents or weak anionic polymer high-efficiency wetting and dispersing agents.

[0023] The lubricant can be selected from one or more of oil-soluble phosphate, polyvinyl pyrrolidone, oleic acid, potassium oleate, oleic acid soap, triethyl phosphate, high molecular weight polydimethylsiloxane, potassium linoleate, sodium oleate and sodium ricinoleate. The lubricant forms a lubricating film on the contact surface between the pen tip and the pen holder to effectively reduce the friction coefficient and prevent the pen tip from being worn. If the amount is too low, the pen tip will be worn out, the line will be broken, and the line will be drawn on one side. If the amount is too high, the pen tip will accumulate ink.

[0024] The antiseptic and mildew preventer can be selected from one or more of phenoxyethanol, iodopropynyl butyl carbamate, Kathon LXE, Proxel XL2, Rocima 623 and polyquaternium salt. The pH adjuster is selected from one or more of 2-amino-2-methyl-1-propanol, sodium hydroxide, triethanolamine and ammonia water. The same type of antiseptic and mildew preventer has a corresponding optimal applicable pH range, which can exert its maximum antiseptic effect. The pH range of the heat-erasable neutral ink of the present invention is 7-9, and its applicable range has been fully considered when screening the bactericide.

[0025] The rust inhibitor can be selected from one or more of benzotriazole octylbenzotriazole, dodecylbenzotriazole, N,N-bis(benzotriazole methylene) laurylamine, toluenetriazole and naphthotriazole. The rust inhibitor forms and stores a lubricating film on the surface of each component of the pen tip, which can inhibit corrosion caused by moisture and many other chemical components.

[0026] The present invention also provides a method for preparing the heat-erasable neutral ink, comprising: S1, adding modified xanthan gum into deionized water and dispersing it evenly; S2, adding other components while stirring to obtain the heat-erasable neutral ink.

[0027] In an optional embodiment, the other components added in step S2 may be a moisturizer, a wetting and dispersing agent, a lubricant, a bactericide, a rust inhibitor, a pH regulator, and a temperature-variable pigment paste added in sequence.

[0028] The present invention is further described below by specific examples. However, these examples are merely exemplary and do not constitute any limitation to the scope of the present invention. In the following examples and comparative examples, the reagents, materials and instruments used are all commercially available unless otherwise specified.

[0029] Example 1

[0030] Preparation of compounds with benzotriazole groups

[0031] (1) Add 8 ml of 0.1 mol / l hydrochloric acid solution to 9% o-nitroaniline aqueous solution and place in an ice-water bath, maintain at about zero degrees, add excess sodium nitrite, and stir to react for 30 minutes.

[0032] (2) Add thiourea and excess nitrous acid to react until the starch-KI test paper turns blue, then filter.

[0033] (3) Add 3,5-dihydroxytoluene dropwise to the solution obtained in step (2) in an ice-water bath, react for 2-3 hours, and recrystallize by mixing ethanol and water in a ratio of 1:1. (4) The product obtained in step (3) is reduced and cyclized using a sodium sulfide-zinc powder method to obtain a compound with a benzotriazole group. (5) The product obtained in step (4) is dissolved in a tetrahydrofuran solution, and acryloyl chloride is added to react in an alkaline ice-water bath environment, and purified to obtain 2-(2′-hydroxy-4′-acryloyl-6′-methyl)-benzotriazole.

[0034] Preparation of modified xanthan gum

[0035] Modified xanthan gum was prepared by a four-necked flask equipped with a mechanical stirrer, a reflux condenser, a thermometer and a N2 inlet and outlet pipe. Xanthan gum (1 g) was dissolved in 150 mL of distilled water at room temperature for 60 minutes under constant temperature stirring. Then, the prepared 2-(2′-hydroxy-4′-acryloyl-6′-methyl)-benzotriazole (15 g) was added to the xanthan gum solution and stirred for 30 minutes, and N2 was passed to remove dissolved oxygen. When the temperature reached 70°C, 0.3 g of hydrogen peroxide was added, and an ethanol / water mixture (4:1, v / v) was added under high-speed stirring after the reaction for 4 hours, and then soaked in an ethanol / water mixture (4:1, v / v) for 24 hours, and the modified xanthan gum was collected by filtration.

[0036] Preparation of heat-erasable neutral ink

[0037] (a) Add the prepared modified xanthan gum to deionized water and stir for 2 hours until it is completely dissolved and stirred evenly. (b) Add moisturizer, wetting dispersant, lubricant, antiseptic and mildew inhibitor, rust inhibitor, and pH adjuster in sequence while stirring. (c) Add the temperature-variable pigment paste and stir it thoroughly with a constant speed mixer, set the stirring rate to 400 rpm, and disperse and stir for 1 hour. (d) Adjust the pH to 8.0 to obtain a heat-erasable neutral ink.

[0038] The specific substances and contents of each component are shown in Table 1.

[0039] Example 2-3

[0040] The preparation method of Example 2-3 is the same as that of Example 1, and the composition of the thermally erasable neutral ink is also the same as that of Example 1, except for the content of each component. The specific composition is shown in Table 1.

[0041] Table 1

[0042]

[0043]

[0044] Comparative Example 1

[0045] Except that the thickener is xanthan gum, other components, contents and preparation methods are the same as those in Example 1.

[0046] Comparative Example 2

[0047] The thickener is xanthan gum, and an ultraviolet absorber is added, and the other components are the same as those in Example 1. The preparation method is also the same as that in Example.

[0048] The components and their contents are shown in Table 2.

[0049] Table 2

[0050]

[0051] The inks prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-2 were made into pen refills, and the pen refills using the inks in the above-mentioned Examples and Comparative Examples were tested in accordance with the light resistance regulations of GB / T37853-2019. The test results are shown in Table 3.

[0052] Table 3

[0053]

[0054] It can be seen from the data in Table 3 that the inks prepared in Examples 1, 2, 3 and Comparative Examples 1-2 of the present invention have normal marking, good writing performance, good line erasability and light resistance. Considering the viscosity, ink output, marking, erasability and light resistance, the conventional performance of the inks prepared in Examples 1, 2, 3 and Comparative Examples 1-2 is normal. After placing the pen refills under the conditions specified in GB / T 37853-2019 for light resistance, it can be seen that the line traces of the ink prepared in Comparative Example 1 are significantly lighter, and the line traces of the inks prepared in the remaining examples are normal. After 24 hours of ultraviolet irradiation, the line traces of the inks in Examples 1, 2, and 3 are normal, and the line traces of the inks in Comparative Examples 1-2 are all lighter to varying degrees. According to the light resistance test of GB / T 37853-2019, the line traces of the ink in Comparative Example 1 disappear, the line traces of the ink in Comparative Example 2 fade, and the line traces of the inks in Examples 1, 2, and 3 are normal. By comparing the above embodiments with the comparative examples, the results show that the modified xanthan gum can improve the light resistance of the ink, and increasing the xanthan gum content will reduce the ink output, but will not affect the light resistance.

[0055] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A heat-erasable neutral ink, characterized in that: Including temperature-sensitive pigment paste and thickener; The thickener is modified xanthan gum, and the modified xanthan gum includes a benzotriazole group.

2. The heat-erasable neutral ink according to claim 1, characterized in that: The molar content of the benzotriazole group in the modified xanthan gum is 0.02-0.024 mol / g.

3. The heat-erasable neutral ink according to claim 1 or 2, characterized in that: According to weight percentage, the heat-erasable neutral ink includes: 20-40% of the temperature-variable pigment paste, 0.25-0.35% of the thickener, 5-15% of the moisturizer, 1-5% of the wetting dispersant, 0.2-1% of the lubricant, 0.2-0.5% of the preservative and mildew preventer, 0.2-0.5% of the rust inhibitor, 0.2-1% of the pH adjuster, and the balance is deionized water.

4. The thermally erasable neutral ink according to claim 3, characterized in that: The temperature-changing pigment paste is a dispersed temperature-changing pigment paste.

5. The thermally erasable neutral ink according to claim 3, characterized in that: The moisturizing agent is selected from one or more of glycerol, polyethylene glycol, β-glucan, glycereth-26, glycereth-7, propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, sorbitol, sorbeth-6, sorbeth-40, maltitol, lactose and sorbitol; and / or The wetting and dispersing agent is selected from one or more of nonionic wetting and dispersing agents or weak anionic polymer high-efficiency wetting and dispersing agents; and / or The lubricant is selected from one or more of oil-soluble phosphate esters, polyvinyl pyrrolidone, oleic acid, potassium oleate, oleic acid soap, triethyl phosphate, high molecular weight polydimethylsiloxane, potassium linoleate, sodium oleate and sodium ricinoleate; and / or The preservative and mildew preventer is selected from one or more of phenoxyethanol, iodopropynyl butyl carbamate, Kathon LXE, Proxel XL2, Rocima 623 and polyquaternium salt; and / or The rust inhibitor is selected from one or more of benzotriazole octylbenzotriazole, dodecylbenzotriazole, N,N-bis(benzotriazole methylene) laurylamine, toluenetriazole and naphthyltriazole; and / or The pH regulator is selected from one or more of 2-amino-2-methyl-1-propanol, sodium hydroxide, triethanolamine and ammonia water.

6. A method for preparing the heat-erasable neutral ink according to any one of claims 1 to 5, characterized in that: include: S1, adding the thickener into deionized water and dispersing it uniformly; S2, adding other components while stirring to obtain the heat-erasable neutral ink.

7. The preparation method according to claim 6, characterized in that: The order of adding the other components in the step S2 is the moisturizer, the wetting and dispersing agent, the lubricant, the bactericide, the rust inhibitor, the pH regulator, and the temperature-variable pigment paste.

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