Anti-sedimentation, inorganic-pigment, color-variable, Anti-counterfeiting printing ink and preparation method therefor

Abstract

The present invention provides a preparation method for an anti-sedimentation, inorganic-pigment, color-variable, anti-counterfeiting printing ink. The method comprises: first, using fillers and a pigment to prepare slurries separately, and controlling particle sizes of the fillers to create particle size mismatch among three fillers; while mixing the slurries with a partial amount of a polyvinyl butyral slurry, allowing the particle-size-mismatched fillers to be fully encapsulated by resin to form a well-suspended mixed slurry; then, performing low-speed grinding of the mixed slurry together with organic bentonite to further improve the suspension performance of the mixed slurry; on this basis, adding and dispersing an acrylic acid slurry and thermochromic capsules to further encapsulate the pigment and the fillers by the resin; and finally, using the remaining polyvinyl butyral slurry and additives to adjust the formulation, so as to increase the viscosity of the material. The resulting anti-counterfeiting ink maintains high anti-counterfeiting performance while exhibiting minimal sedimentation after prolonged storage and demonstrates good usability.

Description

Anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of anti-counterfeiting inks, and in particular to an anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink and a preparation method thereof. Background Art

[0002] Anti-counterfeiting inks are special inks that have anti-counterfeiting properties due to the addition of special substances. These inks undergo certain changes under specific conditions, allowing them to print visible or invisible marks to facilitate verification and prevent counterfeiting. Anti-counterfeiting inks are an extremely important field of anti-counterfeiting technology, used in the production of security printed products and have a wide range of applications.

[0003] Pigments and fillers are generally added to anti-counterfeiting inks to enhance product performance and reduce costs, such as inorganic pigments such as iron oxide yellow and iron oxide red, and fillers such as titanium dioxide and talc. Some inks contain higher levels of pigments and fillers as needed. The pigments and fillers have a high specific gravity, and in this case, the resin cannot fully wrap the ink, resulting in serious sedimentation after the ink is left to stand.

[0004] Ink sedimentation can make it difficult to disperse evenly when printing, affecting the concentration during printing and the inability to restore the color of the standard sample, thereby affecting printing quality. It can even cause the sedimented slurry to be unusable and become solid waste. Therefore, when studying the anti-counterfeiting performance of anti-counterfeiting inks, it is also necessary to consider the ink's sedimentation and improve the ink's performance.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to address the problem that existing inks with a high pigment-filler ratio are prone to precipitation, and to provide an anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink and a preparation method thereof. Through design and formulation, combined with adjustments to the preparation process, the problem of precipitation of the ink after long-term storage is solved, the performance of the ink is improved, and the subsequent printing quality is guaranteed.

[0007] According to a first aspect of the present invention, there is provided a method for preparing an anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink, comprising the following steps:

[0008] Step 1, weighing the raw materials in proportion, and using a cosolvent to respectively prepare an acrylic acid slurry, a polyvinyl butyral slurry, a titanium dioxide slurry, a calcium carbonate slurry, a talc slurry, and an inorganic pigment slurry; wherein the particle sizes of the titanium dioxide, calcium carbonate, and talc are different, thereby forming a mismatch of different particle sizes;

[0009] Step 2: adding titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry to polyvinyl butyral slurry in sequence under stirring, stirring and dispersing uniformly to obtain a mixed slurry;

[0010] Step 3: Add the mixed slurry, organic bentonite, and part of the deionized water into the grinder in sequence, and grind to the required fineness at a speed of no more than 250 kg / h to obtain an intermediate material;

[0011] Step 4: Add the intermediate material and acrylic acid slurry into a reactor and disperse them evenly, then add the thermochromic capsule and continue stirring to disperse them evenly to obtain an ink precursor;

[0012] Step 5: Evenly mix the remaining polyvinyl butyral slurry, the remaining deionized water and the remaining cosolvent to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

[0013] As an optional embodiment, the raw materials of the ink, calculated in percentage by weight, include: 12% to 18% water-soluble resin, 15% to 30% deionized water, 10% to 15% co-solvent, 10% to 15% thermochromic capsules, 8% to 15% inorganic pigments, 25% to 35% fillers, and 2% to 4% organic bentonite; wherein the water-soluble resin includes water-soluble polyvinyl butyral and aqueous acrylic emulsion, and the filler includes titanium dioxide, calcium carbonate and talc.

[0014] As an optional embodiment, the mass ratio of the water-soluble polyvinyl butyral to the aqueous acrylic emulsion is (2-4):(5-7).

[0015] As an optional embodiment, the mass ratio of titanium dioxide, calcium carbonate and talc is (5-3):(1-2):1, and the particle size relationship of titanium dioxide, calcium carbonate and talc is: titanium dioxide < calcium carbonate < talc.

[0016] As an optional embodiment, the inorganic pigment includes iron oxide yellow and iron oxide red.

[0017] As an optional embodiment, the mass ratio of yellow iron oxide to red iron oxide is 1:1.

[0018] As an optional embodiment, the co-solvent is a combination of one or more of ethanol, isopropanol, and n-propanol.

[0019] As an optional embodiment, in step 1 and step 5, the mass ratio of the cosolvent is (7-9):(1-3), and the mass ratio of the water-soluble polyvinyl butyral is (7-9):(1-3).

[0020] As an optional embodiment, in step 3 and step 5, the mass ratio of deionized water used is (7-9):(1-3).

[0021] According to a second aspect of the present invention, there is provided an anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink prepared by the aforementioned method.

[0022] It can be seen from the above technical scheme of the present invention that the preparation method of the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink proposed by the present invention is to first prepare the filler and pigment into slurry separately, and then control the particle size of the filler to form a particle size mismatch between the three fillers. In the process of mixing with part of the polyvinyl butyral slurry, the filler with particle size mismatch is fully wrapped by the resin to form a mixed slurry with good suspension effect. The mixed slurry is then ground at a low speed with organic bentonite to further improve the suspension performance of the mixed slurry. On this basis, acrylic acid slurry and thermochromic capsules are added and dispersed to further wrap the color filler with resin. Finally, the remaining polyvinyl butyral slurry and additives are used for tempering to increase the viscosity of the material. The anti-counterfeiting ink obtained in this way has good performance in use while maintaining high anti-counterfeiting performance and basically no precipitation after long-term storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a picture of a precipitation performance test in an example of the present invention. DETAILED DESCRIPTION

[0024] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0025] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to be comprehensive. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of a number of ways.

[0026] In an exemplary embodiment of the present invention, a method for preparing an anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is provided, comprising the following steps:

[0027] Step 1, weighing the raw materials in proportion, and using a cosolvent to respectively prepare an acrylic acid slurry, a polyvinyl butyral slurry, a titanium dioxide slurry, a calcium carbonate slurry, a talc slurry, and an inorganic pigment slurry; wherein the particle sizes of the titanium dioxide, calcium carbonate, and talc are different, thereby forming a mismatch of different particle sizes;

[0028] Step 2: adding titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry to polyvinyl butyral slurry in sequence under stirring, stirring and dispersing uniformly to obtain a mixed slurry;

[0029] Step 3: Add the mixed slurry, organic bentonite, and part of the deionized water into the grinder in sequence, and grind to the required fineness at a speed of no more than 250 kg / h to obtain an intermediate material;

[0030] Step 4: Add the intermediate material and acrylic acid slurry into a reactor and disperse them evenly, then add the thermochromic capsules and continue stirring and dispersing them evenly to obtain an ink precursor;

[0031] Step 5: Evenly mix the remaining polyvinyl butyral slurry, the remaining deionized water and the remaining cosolvent to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

[0032] As an optional embodiment, the raw materials of the ink, calculated in percentage by weight, include: 12% to 18% water-soluble resin, 15% to 30% deionized water, 10% to 15% co-solvent, 10% to 15% thermochromic capsules, 8% to 15% inorganic pigments, 25% to 35% fillers, and 2% to 4% organic bentonite; wherein the water-soluble resin includes water-soluble polyvinyl butyral and aqueous acrylic emulsion, and the filler includes titanium dioxide, calcium carbonate and talc.

[0033] As an optional embodiment, the mass ratio of the water-soluble polyvinyl butyral to the aqueous acrylic emulsion is (2-4):(5-7).

[0034] As an optional embodiment, the mass ratio of titanium dioxide, calcium carbonate and talc is (5-3):(1-2):1, and the particle size relationship of titanium dioxide, calcium carbonate and talc is: titanium dioxide < calcium carbonate < talc.

[0035] In one preferred embodiment, the particle size of titanium dioxide is in the range of 0.2 to 1 μm, the particle size of calcium carbonate is in the range of 10 to 20 μm, and the particle size of talc is in the range of 30 to 40 μm.

[0036] It should be understood that the above particle size refers to the median particle size of the powder, that is, the D50 value.

[0037] As an optional embodiment, the inorganic pigment includes iron oxide yellow and iron oxide red.

[0038] As an optional embodiment, the mass ratio of yellow iron oxide to red iron oxide is 1:1.

[0039] As an optional embodiment, the color changing temperature of the thermochromic capsule is 0-70°C.

[0040] It is understandable that inorganic pigments include but are not limited to iron oxide yellow and iron oxide red, and can be selected and formulated according to actual color needs. The color to be changed can also be adjusted by selecting different colors of thermochromic capsules and inorganic pigments according to actual conditions.

[0041] As an optional embodiment, the co-solvent is a combination of one or more of ethanol, isopropanol, and n-propanol.

[0042] As an optional embodiment, in step 1 and step 5, the mass ratio of the cosolvent is (7-9):(1-3), and the mass ratio of the water-soluble polyvinyl butyral is (7-9):(1-3).

[0043] As an optional embodiment, in step 3 and step 5, the mass ratio of deionized water used is (7-9):(1-3).

[0044] In another exemplary embodiment of the present invention, a color-changing anti-counterfeiting printing ink with anti-precipitation inorganic pigments prepared by the above method is also provided. The ink has basically no precipitation after 30 days, good performance in use, and excellent anti-counterfeiting performance.

[0045] For better understanding, the present invention will be further described below with reference to specific examples, but the processing technology is not limited thereto, and the content of the present invention is not limited thereto.

[0046] Unless otherwise specified, the reagents used in the following examples are commercially available.

[0047] The particle size of the titanium dioxide used is in the range of 0.2 to 1 μm, the particle size of the calcium carbonate is in the range of 10 to 20 μm, and the particle size of the talc is in the range of 30 to 40 μm; the mass ratio of the titanium dioxide, calcium carbonate and talc is 3:1:1.

[0048] The mass ratio of water-soluble polyvinyl butyral and water-based acrylic emulsion is 1:3, the inorganic pigments are iron oxide yellow and iron oxide red, and the mass ratio is 1:1; the cosolvent is ethanol, and the thermochromic capsule is yellow.

[0049] Example 1

[0050] [Preparation of water-soluble polyvinyl butyral]

[0051] At room temperature, 12 g (0.002 mol) of polyvinyl butyral, 9 g (0.0608 mol) of phthalic anhydride, 0.126 g (0.0039 mol) of tetrabutylammonium bromide, and 200 mL of dimethylformamide were added to a four-necked flask and stirred evenly. The temperature was gradually raised to 60°C during stirring, and then the reaction was continued at 60°C for 6 hours. The reaction was stopped, cooled, and 100 mL of acetone solution was added. Stirring was continued for 30 minutes. After uniform mixing, the mixture was dispersed in distilled water, and the dispersion was filtered several times. The filter cake was dried to obtain water-soluble polyvinyl butyral.

[0052] Example 2

[0053] Step 1: Weigh the raw materials in proportion: 18% water-soluble resin, 20% deionized water, 10% cosolvent, 10% thermochromic capsule, 13% inorganic pigment, 27% filler, and 2% organic bentonite;

[0054] Aqueous acrylic emulsion, partially water-soluble polyvinyl butyral (prepared according to the method of Example 1), titanium dioxide, calcium carbonate, talc, and inorganic pigments were respectively prepared into acrylic slurry, polyvinyl butyral slurry, titanium dioxide slurry, calcium carbonate slurry, talc slurry, and inorganic pigment slurry using a cosolvent.

[0055] Step 2: Under stirring conditions, titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry are added to the polyvinyl butyral slurry in sequence, and stirred and dispersed uniformly at a speed of 1000 rpm to obtain a mixed slurry.

[0056] Step 3: Add the mixed slurry, organic bentonite, and part of the deionized water into the grinder in sequence, and grind at a speed of 250 kg / h to the required fineness ≤ 15 μm to obtain the intermediate material.

[0057] Step 4: Add the intermediate material and acrylic acid slurry into the reactor, disperse them evenly at a speed of 800 rpm, then add the thermochromic capsule and continue stirring and dispersing them evenly at a speed of 800 rpm to obtain an ink precursor.

[0058] Step 5: Evenly mix the remaining polyvinyl butyral slurry, the remaining deionized water and the remaining cosolvent to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

[0059] Among them, in step 1 and step 5, the mass ratio of the cosolvent is 7:3, and the mass ratio of the water-soluble polyvinyl butyral is 9:1; in step 3 and step 5, the mass ratio of deionized water is 9:1.

[0060] Example 3

[0061] Step 1: Weigh the raw materials in proportion: 12% water-soluble resin, 15% deionized water, 15% cosolvent, 11% thermochromic capsule, 8% inorganic pigment, 35% filler, and 4% organic bentonite;

[0062] Aqueous acrylic emulsion, partially water-soluble polyvinyl butyral (prepared according to the method of Example 1), titanium dioxide, calcium carbonate, talc, and inorganic pigments were respectively prepared into acrylic slurry, polyvinyl butyral slurry, titanium dioxide slurry, calcium carbonate slurry, talc slurry, and inorganic pigment slurry using a cosolvent.

[0063] Step 2: Under stirring conditions, titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry are added to the polyvinyl butyral slurry in sequence, and stirred and dispersed uniformly at a speed of 1000 rpm to obtain a mixed slurry.

[0064] Step 3: Add the mixed slurry, organic bentonite, and part of the deionized water into the grinder in sequence, and grind at a speed of 250 kg / h to the required fineness ≤ 15 μm to obtain the intermediate material.

[0065] Step 4: Add the intermediate material and acrylic acid slurry into the reactor, disperse them evenly at a speed of 800 rpm, then add the thermochromic capsule and continue stirring and dispersing them evenly at a speed of 800 rpm to obtain an ink precursor.

[0066] Step 5: Evenly mix the remaining polyvinyl butyral slurry, the remaining deionized water and the remaining cosolvent to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

[0067] In step 1 and step 5, the mass ratio of the cosolvent is 4:1, and the mass ratio of the water-soluble polyvinyl butyral is 4:1; in step 3 and step 5, the mass ratio of deionized water is 4:1.

[0068] Example 4

[0069] Step 1: Weigh the raw materials in proportion: 15% water-soluble resin, 25% deionized water, 10% cosolvent, 10% thermochromic capsule, 13% inorganic pigment, 25% filler, and 2% organic bentonite;

[0070] Aqueous acrylic emulsion, partially water-soluble polyvinyl butyral (prepared according to the method of Example 1), titanium dioxide, calcium carbonate, talc, and inorganic pigments were respectively prepared into acrylic slurry, polyvinyl butyral slurry, titanium dioxide slurry, calcium carbonate slurry, talc slurry, and inorganic pigment slurry using a cosolvent.

[0071] Step 2: Under stirring conditions, titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry are added to the polyvinyl butyral slurry in sequence, and stirred and dispersed uniformly at a speed of 1000 rpm to obtain a mixed slurry.

[0072] Step 3: Add the mixed slurry, organic bentonite, and part of the deionized water into the grinder in sequence, and grind at a speed of 250 kg / h to the required fineness ≤ 15 μm to obtain the intermediate material.

[0073] Step 4: Add the intermediate material and acrylic acid slurry into the reactor, disperse them evenly at a speed of 800 rpm, then add the thermochromic capsule and continue stirring and dispersing them evenly at a speed of 800 rpm to obtain an ink precursor.

[0074] Step 5: Evenly mix the remaining polyvinyl butyral slurry, the remaining deionized water and the remaining cosolvent to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

[0075] Among them, in step 1 and step 5, the mass ratio of the cosolvent is 9:1, and the mass ratio of the water-soluble polyvinyl butyral is 7:3; in step 3 and step 5, the mass ratio of deionized water is 7:3.

[0076] Comparative Example 1

[0077] Step 1: Weigh the raw materials in proportion: 17% water-soluble resin, 25% deionized water, 10% cosolvent, 10% thermochromic capsule, 13% inorganic pigment, and 25% filler;

[0078] The raw materials are sequentially added into the grinder at one time, and ground at a speed of 600 kg / h to a required fineness of ≤15 μm to obtain an intermediate material, which is then tempered to obtain an anti-counterfeiting ink.

[0079] Wherein, the water-soluble polyvinyl butyral was prepared according to the method of Example 1.

[0080] Comparative Example 2

[0081] Step 1: Weigh the raw materials in proportion: 15% water-soluble resin, 25% deionized water, 10% cosolvent, 10% thermochromic capsule, 13% inorganic pigment, 25% filler, and 2% organic bentonite;

[0082] The raw materials are sequentially added into the grinder at one time, and ground at a speed of 600 kg / h to a required fineness of ≤15 μm to obtain an intermediate material, which is then tempered to obtain an anti-counterfeiting ink.

[0083] Wherein, the water-soluble polyvinyl butyral was prepared according to the method of Example 1.

[0084] Comparative Example 3

[0085] Step 1: Weigh the raw materials in proportion: 15% water-soluble resin, 25% deionized water, 10% cosolvent, 10% thermochromic capsule, 13% inorganic pigment, 25% filler, and 2% organic bentonite;

[0086] Aqueous acrylic emulsion, partially water-soluble polyvinyl butyral (prepared according to the method of Example 1), titanium dioxide, calcium carbonate, talc, and inorganic pigments were respectively prepared into acrylic slurry, polyvinyl butyral slurry, titanium dioxide slurry, calcium carbonate slurry, talc slurry, and inorganic pigment slurry using a cosolvent.

[0087] Step 2: Under stirring conditions, titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry are added to the polyvinyl butyral slurry in sequence, and stirred and dispersed uniformly at a speed of 1000 rpm to obtain a mixed slurry.

[0088] Step 3: Add the mixed slurry and part of the deionized water into the grinder in sequence, grind at a speed of 600 kg / h to the required fineness ≤ 15 μm, and obtain the intermediate material.

[0089] Step 4: Add the intermediate material and acrylic acid slurry into the reactor, disperse them evenly at a speed of 800 rpm, then add the thermochromic capsule and continue stirring and dispersing them evenly at a speed of 800 rpm to obtain an ink precursor.

[0090] Step 5: Evenly mix the remaining polyvinyl butyral slurry and the remaining deionized water to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

[0091] Among them, in step 1 and step 5, the mass ratio of water-soluble polyvinyl butyral is 7:3; in step 3 and step 5, the mass ratio of deionized water is 7:3.

[0092] Comparative Example 4

[0093] Step 1: Weigh the raw materials in proportion: 15% water-soluble resin, 25% deionized water, 10% cosolvent, 10% thermochromic capsule, 13% inorganic pigment, 25% filler, and 2% organic bentonite;

[0094] Aqueous acrylic emulsion, partially water-soluble polyvinyl butyral (prepared according to the method of Example 1), titanium dioxide, calcium carbonate, talc, and inorganic pigments were respectively prepared into acrylic slurry, polyvinyl butyral slurry, titanium dioxide slurry, calcium carbonate slurry, talc slurry, and inorganic pigment slurry using a cosolvent.

[0095] Step 2: Under stirring conditions, titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry are added to the polyvinyl butyral slurry in sequence, and stirred and dispersed uniformly at a speed of 1000 rpm to obtain a mixed slurry.

[0096] Step 3: Add the mixed slurry, organic bentonite, and part of the deionized water into the grinder in sequence, and grind at a speed of 600 kg / h to a desired fineness of ≤15 μm to obtain an intermediate material.

[0097] Step 4: Add the intermediate material and acrylic acid slurry into the reactor, disperse them evenly at a speed of 800 rpm, then add the thermochromic capsule and continue stirring and dispersing them evenly at a speed of 800 rpm to obtain an ink precursor.

[0098] Step 5: Evenly mix the remaining polyvinyl butyral slurry, the remaining deionized water and the remaining cosolvent to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

[0099] Among them, in step 1 and step 5, the mass ratio of the cosolvent is 9:1, and the mass ratio of the water-soluble polyvinyl butyral is 7:3; in step 3 and step 5, the mass ratio of deionized water is 7:3.

[0100] Performance Testing

[0101] The performance tests were conducted on the ink samples of Examples 2-4 and Comparative Examples 1-4, and the results are shown in Table 1.

[0102] Table 1

[0103] Sedimentation test

[0104] The ink samples of Example 4 and Comparative Examples 1-4 were respectively placed in bottles with equal weights. After standing for 30 days, the sedimentation was observed.

[0105] It can be seen from the observation that the sample of Example 4 has almost no precipitation and good suspension performance, while the samples of Comparative Examples 1-4 all show obvious stratification, especially the sample of Comparative Example 1, which has a large amount of precipitation and is difficult to stir, as shown in Figure 1.

[0106] As can be seen from the above, the anti-counterfeiting ink obtained by the present invention has excellent anti-precipitation performance and maintains excellent anti-counterfeiting performance by designing the components and adjusting the process.

[0107] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A method for preparing a color-changing anti-counterfeiting printing ink containing an anti-precipitation inorganic pigment, characterized in that: The following steps are involved: Step 1, weighing the raw materials in proportion, and using a cosolvent to respectively prepare an acrylic acid slurry, a polyvinyl butyral slurry, a titanium dioxide slurry, a calcium carbonate slurry, a talc slurry, and an inorganic pigment slurry; wherein the particle sizes of the titanium dioxide, calcium carbonate, and talc are different, thereby forming a mismatch of different particle sizes; Step 2: adding titanium dioxide slurry, calcium carbonate slurry, talc slurry and inorganic pigment slurry to polyvinyl butyral slurry in sequence under stirring, stirring and dispersing uniformly to obtain a mixed slurry; Step 3: Add the mixed slurry, organic bentonite, and part of the deionized water into the grinder in sequence, and grind to the required fineness at a speed of no more than 250 kg / h to obtain an intermediate material; Step 4: Add the intermediate material and acrylic acid slurry into a reactor and disperse them evenly, then add the thermochromic capsule and continue stirring to disperse them evenly to obtain an ink precursor; Step 5: Evenly mix the remaining polyvinyl butyral slurry, the remaining deionized water and the remaining cosolvent to obtain a regulating liquid, and add the regulating liquid to the ink precursor to adjust the color concentration and viscosity. After filtering, the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink is obtained.

2. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 1, characterized in that: The raw materials of the ink include, by weight percentage: 12% to 18% water-soluble resin, 15% to 30% deionized water, 10% to 15% cosolvent, 10% to 15% thermochromic capsules, 8% to 15% inorganic pigments, 25% to 35% fillers, and 2% to 4% organic bentonite; wherein the water-soluble resin includes water-soluble polyvinyl butyral and water-based acrylic emulsion, and the fillers include titanium dioxide, calcium carbonate, and talc.

3. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 2, characterized in that: The mass ratio of the water-soluble polyvinyl butyral to the aqueous acrylic emulsion is (2-4):(5-7).

4. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 2, characterized in that: The mass ratio of titanium dioxide, calcium carbonate and talc is (5-3):(1-2):1, and the particle size relationship of titanium dioxide, calcium carbonate and talc is: titanium dioxide < calcium carbonate < talc.

5. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 1 or 2, characterized in that: The inorganic pigments include iron oxide yellow and iron oxide red.

6. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 5, characterized in that: The mass ratio of iron oxide yellow to iron oxide red is 1:

1.

7. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 1 or 2, characterized in that: The co-solvent is a combination of one or more of ethanol, isopropanol, and n-propanol.

8. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 1, characterized in that: In the steps 1 and 5, the mass ratio of the cosolvent is (7-9):(1-3), and the mass ratio of the water-soluble polyvinyl butyral is (7-9):(1-3).

9. The method for preparing the anti-precipitation inorganic pigment color-changing anti-counterfeiting printing ink according to claim 1, characterized in that: In step 3 and step 5, the mass ratio of deionized water used is (7-9):(1-3).

10. A color-changing anti-counterfeiting printing ink containing an anti-precipitation inorganic pigment prepared by the method according to any one of claims 1 to 9.

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