Anti-counterfeiting color-changing ink for two-dimensional code and preparation method thereof

Abstract

The invention discloses an anti-counterfeiting color-changing ink for a two-dimensional code and a preparation method thereof, the ink takes heat discoloration powder as a functional material, and the ink is endowed with a multi-color-temperature change characteristic by utilizing the reversible phase change effect of a pigment-long-chain alkane compound and mixing the heat discoloration powder with different color change temperatures and colors. A thermal expansion microcapsule foaming agent is also added into the ink, so that embossment touch can be formed after printing. In addition, the ink adopts water-based acrylic acid and rosin resin as film-forming substances, and has excellent printability and durability. The preparation method comprises the following steps: uniformly mixing and stirring the ink components, grinding to required fineness, printing on the surface of the two-dimensional code through a silk screen, and drying to obtain the two-dimensional code with multiple anti-counterfeiting characteristics. The ink is rich and diversified in color changing effect, has the characteristics of touch, glossiness difference and the like, greatly improves the anti-counterfeiting capability of the two-dimensional code, has the advantages of simple process, low cost, environmental friendliness and the like, and has a wide application prospect in the anti-counterfeiting field.

Description

Technical Field

[0001] The invention relates to the technical field of anti-counterfeiting inks, and in particular to an anti-counterfeiting color-changing ink for a two-dimensional code and a preparation method thereof. Background Art

[0002] The more common anti-counterfeiting methods currently available are as follows:

[0003] The first is the laser anti-counterfeiting mark, which uses laser invisible ink fluorescent ink printing technology to print the product logo or special identification pattern into the product's anti-counterfeiting label, and the same type of products use the same label. Because anti-counterfeiting labels are easier to forge, and forged anti-counterfeiting labels are used on counterfeit products, causing confusion between the authenticity of the products, it is difficult to effectively prevent counterfeiting.

[0004] The second type is password anti-counterfeiting labels, which use a method of coding each product with a set of numbers. The codes of each product are different, and the numbers are printed on the label and covered up. At the same time, the numbers are stored in a computer database that consumers can query. When consumers buy products, they enter the numbers on the label into the computer database through telephone or networked computers for comparison and identification. If they are the same, they are true, and if they are different, they are false. The method is simple, easy to identify, and not easy to forge. However, in actual use, because the coding data is uniformly generated by the computer and then printed on the label, the coding data representing the authenticity of the product may be illegally copied and forged. At the same time, the code can also be recycled from the code on the unqueried product and affixed to the fake product, so the anti-counterfeiting effect is difficult to guarantee.

[0005] The third is texture anti-counterfeiting, which uses the texture features on the label to prevent counterfeiting. Although it is difficult to forge, since only the serial number of the label is set, and it is a clear code, each label can be queried repeatedly. Counterfeiters can copy the serial number on the label and the necessary texture features reflected during the query, that is, the presence or absence of the square, through warehouse keeper or salesperson, and then forge in batches according to this feature. In summary, the existing anti-counterfeiting methods all have certain shortcomings, and therefore cannot fundamentally prevent counterfeit products.

[0006] With the emergence and promotion of QR code digital information carriers, it has great advantages in product traceability, commodity information service tracking, online business, sharing economy, etc., and is widely used in various industries. QR code is also more widely used for anti-counterfeiting information code, but the QR code itself is very easy to copy and imitate as a printed product, resulting in the proliferation of anti-counterfeiting and the continuous emergence of counterfeit products. Therefore, it is very important to ensure the authenticity and non-replicability of the QR code. Printing the QR code with special ink makes the QR code invisible or ordinary at room temperature, and the anti-counterfeiting QR code is visible by changing the temperature, which will effectively improve the anti-counterfeiting security of the QR code.

[0007] Therefore, it is necessary to develop a new anti-counterfeiting color-changing ink with multiple color-changing mechanisms, stable color-changing effects, and good reversibility to further improve the anti-counterfeiting performance of the QR code. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides an anti-counterfeiting color-changing ink for QR codes and a preparation method thereof. The ink is temperature responsive, presents different colors at different temperatures, and has good reversibility of color change and good weather resistance. It is suitable for printing QR codes with anti-counterfeiting features, giving the QR codes excellent anti-counterfeiting properties.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] In the first aspect, the present invention provides an anti-counterfeiting color-changing ink for a two-dimensional code, whose main components and weight portions are: 30-45 parts of a thermochromic powder mixture, 60-80 parts of a resin emulsion, 11-15 parts of a dispersant, 22-35 parts of a foaming agent, 3-5 parts of a leveling agent, 3-8 parts of a solvent, and 1-5 parts of an auxiliary agent; the thermochromic powder mixture is obtained by mixing three thermochromic powders of different thermosensitive temperatures and different colors in the same proportion; the thermochromic powder is a reversible thermochromic powder that changes from colorless to colored at a specific temperature, has a color change temperature range of 5-50°C, and a particle size of 1-10μm.

[0011] Preferably, the resin emulsion is obtained by mixing 30%-40% of water-based acrylic resin emulsion, 20%-40% of acrylic emulsion and 30%-40% of rosin resin emulsion; the total content of the water-based acrylic resin emulsion and the acrylic emulsion is 60%-80% of the total amount of the resin emulsion; the acid value of the rosin in the rosin resin emulsion is 150-200 mgKOH / g, and the softening point is 70-90°C.

[0012] Preferably, the dispersant is an acrylic polymer, which is polymerized by alkyl methacrylate, hydroxyl-containing vinyl monomer and isobutyl methacrylate in a mass ratio of (50-80):(10-30):(10-20); the alkyl methacrylate is selected from one or more of methyl methacrylate, ethyl methacrylate and butyl methacrylate; the hydroxyl-containing vinyl monomer is selected from one or more of hydroxypropyl acrylate, hydroxyethyl acrylate and hydroxypropyl methacrylate.

[0013] Preferably, the foaming agent is a heat-expandable microcapsule, the capsule wall of the heat-expandable microcapsule is acrylamide-acrylonitrile copolymer, and a mixture of butane, pentane and dichloroethane is wrapped in the capsule wall, and the mass ratio of butane, pentane and dichloroethane is (20-50): (20-50): (20-40); the expansion temperature of the heat-expandable microcapsule is 80-120°C, and the diameter after expansion is 2-5 times the original diameter.

[0014] Preferably, the leveling agent is silicone-modified polyacrylate, wherein the mass ratio of the silicone modifier to the polyacrylate is (1-10): (100-80); the silicone modifier is selected from one or more of γ-aminopropyltriethoxysilane and γ-methacrylic acid oxypropyltrimethoxysilane.

[0015] Preferably, the solvent is an alcoholic organic solvent with low toxicity and low volatility, preferably one or more of n-butanol and isopropanol; the boiling point of the alcoholic solvent is 100-150°C, and the solubility parameter is 10-14 (cal / cm 3 )^0.5.

[0016] Preferably, the auxiliary agent includes a plasticizer, a defoamer and a bactericidal preservative, wherein the plasticizer is selected from one or more of dibutyl phthalate and dioctyl phthalate, and the amount used is 0.5-2% of the total amount of ink; the defoamer is selected from one or more of polyether-modified polysiloxane and organosiloxane, and the amount used is 0.2-1% of the total amount of ink; the bactericidal preservative is selected from one or more of 1,2-benzisothiazolin-3-one and 2-hydroxypyridine-N-oxide, and the amount used is 0.1-0.5% of the total amount of ink.

[0017] Preferably, the ink is printed on the surface of the QR code by screen printing, with a screen line count of 250-400 lines / inch and a mesh rate of 30-50%; the printing layer thickness is 10-30 μm; after printing, it is naturally dried or dried with hot air at 40-60°C for 2-10 minutes to obtain an anti-counterfeiting QR code with a temperature-variable pattern, wherein the color of the pattern changes reversibly with temperature.

[0018] In a second aspect, the present invention provides a method for preparing the above-mentioned ink, comprising the following steps:

[0019] (1) printing the anti-counterfeiting color-changing ink evenly on the surface of the two-dimensional code, with a printing layer thickness of 10-30 μm;

[0020] (2) Drying the two-dimensional code printed in step (1) naturally or with hot air at 40-60° C. for 2-10 min to obtain an anti-counterfeiting two-dimensional code with a temperature-dependent pattern.

[0021] Preferably, in step (1), a screen printing process is used, the number of screen lines used is 250-400 lines / inch, and the mesh rate is 30-50%; the tension between the screen and the surface of the two-dimensional code during printing is 10-30N / cm, the hardness of the scraper is 60-80 degrees, and the scraper printing speed is 0.1-1m / s.

[0022] The present invention discloses an anti-counterfeiting color-changing ink for a two-dimensional code and a preparation method thereof, which has the following beneficial effects:

[0023] The present invention selects a plurality of thermochromic powders that can display different colors at different temperatures to mix, and obtains an ink that can realize multi-level color change at different temperatures by configuring with a resin emulsion and a blending agent in proportion. The selected thermochromic powders are all reversible thermochromic powders. The ink can be used to perform superimposed printing of multiple anti-counterfeiting two-dimensional codes, and different anti-counterfeiting two-dimensional codes can be displayed one by one at different temperatures through temperature changes, thereby ensuring the confidentiality of anti-counterfeiting information, and realizing multi-level anti-counterfeiting, and improving the reliability of anti-counterfeiting information. The components selected by the ink are environmentally friendly and pollution-free, have strong adhesion, are not easy to fade, and are not easy to fall off, and can be widely used in the printing of anti-counterfeiting information patterns. DETAILED DESCRIPTION

[0024] Embodiment 1:

[0025] The present embodiment provides an anti-counterfeiting color-changing ink, whose composition and weight parts are as follows: 30 parts of a thermochromic powder mixture, wherein black thermochromic powder (20-30°C), blue thermochromic powder (35-40°C), and red thermochromic powder (45-55°C) are mixed in the same proportion; 18 parts of an aqueous acrylic resin emulsion, 24 parts of an acrylic emulsion, and 18 parts of a rosin resin emulsion, totaling 60 parts; 11 parts of an acrylic polymer dispersant, which is polymerized from butyl methacrylate, hydroxyethyl acrylate, and isobutyl methacrylate in a mass ratio of 70:20:10; 22 parts of a thermally expandable microcapsule foaming agent, whose capsule wall is an acrylamide-acrylonitrile copolymer, containing a mixture of n-butane / ethylene dichloride = 7:3; 3 parts of an organosilicon-modified polyacrylate leveling agent, with the ratio of the organosilicon modifier to the polymer being 1:9; and 3 parts of an isopropanol solvent.

[0026] The above components were mixed and stirred evenly, and ground by a three-roll grinder to a particle size of ≤10 μm to obtain a finished ink. The ink was screen-printed on the surface of the QR code using a 300-mesh screen with a printing thickness of 15 μm, and dried with hot air at 80°C for 5 minutes to obtain an anti-counterfeiting QR code with a temperature-variable pattern.

[0027] The QR code appears black at room temperature. As the temperature rises, the pattern color changes to blue at 35-40°C and to red at 45-55°C. The color change is reversible after cooling.

[0028] Embodiment 2:

[0029] The present embodiment provides an anti-counterfeiting color-changing ink, whose composition and weight parts are as follows: 45 parts of a thermochromic powder mixture, in which black thermochromic powder (20-30°C), blue thermochromic powder (35-40°C), and red thermochromic powder (45-55°C) are mixed in the same proportion; 32 parts of an aqueous acrylic resin emulsion, 16 parts of an acrylic emulsion, and 32 parts of a rosin resin emulsion, totaling 80 parts; 15 parts of an acrylic polymer dispersant, which is polymerized from ethyl methacrylate, hydroxypropyl acrylate, and isobutyl methacrylate in a mass ratio of 60:25:15; 35 parts of a thermally expandable microcapsule foaming agent, the capsule wall of which is an acrylamide-acrylonitrile copolymer, containing a mixture of n-pentane / ethylene dichloride = 1:1; 5 parts of a γ-aminopropyl triethoxysilane-modified polyacrylate leveling agent, with the ratio of the modifier to the polymer being 1:4; and 8 parts of a n-butanol solvent.

[0030] The above components were mixed and stirred evenly, and ground by a sand mill to a particle size of ≤5 μm to obtain a finished ink. The ink was screen-printed on the surface of the QR code using a 380-mesh screen with a printing thickness of 20 μm, and dried with hot air at 50°C for 10 minutes to obtain an anti-counterfeiting QR code with a temperature-variable pattern.

[0031] Compared with Example 1, the color change temperature of the pattern of the two-dimensional code is the same, but the color change is more distinct and has a more obvious raised touch.

[0032] Embodiment 3:

[0033] The present embodiment provides an anti-counterfeiting color-changing ink, whose composition and weight parts are as follows: 38 parts of a thermochromic powder mixture, wherein black thermochromic powder (20-30°C), blue thermochromic powder (35-40°C), and red thermochromic powder (45-55°C) are mixed in the same proportion; 24.5 parts of an aqueous acrylic resin emulsion, 21 parts of an acrylic emulsion, and 24.5 parts of a rosin resin emulsion, totaling 70 parts; 13 parts of an acrylic polymer dispersant, which is polymerized by methyl methacrylate, hydroxypropyl methacrylate, and isobutyl methacrylate in a mass ratio of 55:30:15; 29 parts of a thermally expandable microcapsule foaming agent, the capsule wall of which is an acrylamide-acrylonitrile copolymer, containing a mixture of isobutane / n-pentane / ethylene dichloride = 2:2:1; 4 parts of a γ-methacrylic acid oxypropyl trimethoxysilane modified polyacrylate leveling agent, with the ratio of the modifier to the polymer being 1:19; and 6 parts of a n-propanol solvent.

[0034] The above components were mixed and stirred evenly, and ground by a ball mill to a particle size of ≤8 μm to obtain a finished ink. The ink was screen-printed on the surface of the QR code using a 350-mesh screen with a printing thickness of 18 μm, and dried with hot air at 60°C for 8 minutes to obtain an anti-counterfeiting QR code with a temperature-variable pattern.

[0035] Compared with Examples 1 and 2, the pattern of the two-dimensional code has a slightly weaker touch, but the surface of the printed layer is flatter and smoother, and the color changes are softer and more natural.

[0036] Comparative Example 1:

[0037] This comparative example provides a common black ink, which is composed of: 30 parts of carbon black pigment, 50 parts of water-based acrylic resin emulsion, 5 parts of dispersant, 3 parts of leveling agent, and 5 parts of solvent. The ink is prepared and a two-dimensional code is printed in the same manner as in Example 1. The obtained two-dimensional code is a single black color and has no color change function and anti-counterfeiting feature.

[0038] It can be seen from Examples 1-3 that the ink of the present invention, by mixing three thermochromic powders with different color change temperatures and colors and adding thermally expandable microcapsules, gives the QR code unique multi-color temperature change characteristics and embossed tactile feel, greatly improving the anti-counterfeiting ability of the QR code.

[0039] Different embodiments achieve differentiation in anti-counterfeiting performance, printability, visual effects, etc. by adjusting the types and ratios of ink components, and can be selected according to actual needs. However, the QR code printed with ordinary ink in Comparative Example 1 does not have the above anti-counterfeiting features.

[0040] Embodiment 4:

[0041] The present embodiment provides a method for preparing an anti-counterfeiting color-changing ink, comprising the following steps: (1) weighing 30 parts of a temperature-sensitive color-changing powder mixture, 65 parts of a resin emulsion, 13 parts of a dispersant, 28 parts of a foaming agent, 4 parts of a leveling agent, 5 parts of a solvent, and 3 parts of an auxiliary agent, respectively, adding the mixture to a stirring kettle, and stirring evenly to obtain an ink slurry; (2) grinding the ink slurry obtained in step (1) to a particle size of less than 10 μm to obtain a finished ink; (3) printing the ink obtained in step (2) on the surface of a two-dimensional code by a screen printing process, wherein the number of mesh lines is 300 threads / inch, the mesh rate is 40%, and the thickness of the printing layer is 20 μm; (4) hot-air drying the two-dimensional code printed in step (3) at 50° C. for 5 minutes to obtain an anti-counterfeiting two-dimensional code with a temperature-changing pattern.

[0042] The thermochromic powder mixture is made by mixing three thermochromic powders in the same proportion, namely blue, green and orange, with color change temperatures of 15°C, 30°C and 45°C respectively, and an average particle size of 5μm; the resin emulsion is made by mixing water-based acrylic resin emulsion, acrylic emulsion and rosin resin emulsion in a ratio of 1:1:1; the dispersant is an acrylic polymer obtained by polymerizing butyl methacrylate, hydroxyethyl acrylate and isobutyl methacrylate in a ratio of 7:2:1; the foaming agent is a kind of acrylate polymer; The agent adopts heat-expandable microcapsules with an expansion temperature of 100°C and an expansion ratio of 3 times, and the capsule core is a mixture of butane / pentane / dichloroethane = 4:4:2; the leveling agent adopts γ-aminopropyl triethoxysilane modified polyacrylate, and the ratio of the modifier to the polymer is 1:9; the solvent adopts isopropanol, with a boiling point of 82.5°C and a solubility parameter of 11.5; the auxiliary agents include dioctyl phthalate plasticizer, polyether modified polysiloxane defoamer and 2-hydroxypyridine-N-oxide bactericidal preservative.

[0043] The anti-counterfeiting QR code obtained in this example presents a blue pattern at room temperature. As the temperature rises to 30°C and 45°C, the pattern color changes to green and orange in turn, and the color change is reversible after cooling. The multi-color temperature-changing pattern gives the QR code a unique anti-counterfeiting mark and has excellent anti-counterfeiting performance.

[0044] Working principle:

[0045] The temperature-sensitive color-changing mechanism of the anti-counterfeiting color-changing ink of the present invention mainly comes from the thermochromic powder. Thermochromic powder is a pigment-long-chain alkane complex. At room temperature, the pigment molecules and alkane molecules are tightly stacked and are in a colorless state; when the temperature rises to a certain value, the alkane molecules melt, and the pigment molecules are freed to show color; when the temperature drops, the pigment molecules re-combine with the alkane molecules and the color disappears. By mixing thermochromic powders with different color-changing temperatures and colors, the ink is given a multi-stage color-changing property.

[0046] The ink of the present invention also adds heat-expandable microcapsules as foaming agents. When the ink is heated to a certain temperature, the liquid inside the microcapsules vaporizes and expands, driving the volume of the ink to expand rapidly, forming a raised relief effect on the surface of the printing layer, thereby improving the touch and recognition of the two-dimensional code.

[0047] In addition, the ink of the present invention adopts water-based acrylic acid and rosin resin as film-forming substances, and forms a tough and wear-resistant printing layer after drying; adopts a special acrylic polymer dispersant, which contains hydrophilic groups and hydrophobic groups, can effectively disperse the color powder and improve the dispersion stability of the system; adopts an organosilicon-modified polyacrylate leveling agent to form a lubricating layer with low surface tension on the surface of the ink, promote the spreading of the ink, and improve the flatness of the printing layer; and adds additives such as plasticizers, defoamers, and preservatives to further optimize the performance of the ink.

[0048] The ink is transferred to the surface of the QR code through the screen printing process, and after drying, a pattern layer with uniform thickness and stable color is formed, giving the QR code the temperature-sensitive color-changing anti-counterfeiting property. This anti-counterfeiting method is simple to operate, low-cost, and can be mass-produced, and has good application prospects in the field of product anti-counterfeiting.

[0049] In some possible embodiments, on the basis of the above embodiments, a certain amount of magnetic nanoparticles, such as Fe3O4 nanoparticles, is added. The particle size of the magnetic nanoparticles is 10-100nm, and the amount added is 1%-5% of the total amount of ink. When the pattern printed by the ink is subjected to an external magnetic field, the magnetic nanoparticles will be arranged in a directional manner, changing the reflection and refraction direction of the light, so that the pattern presents different colors.

[0050] Magnetic nanoparticles themselves do not contain pigments, but when they are arranged into an ordered structure under the action of a magnetic field, they form a microscopic structure similar to a grating, which produces diffraction and interference effects on light, making the reflected light appear in rainbow colors. This structural color is fundamentally different from the colors produced by ordinary dyes and pigments and is extremely difficult to replicate.

[0051] The pattern printed with magnetic induction color-changing ink shows normal color when there is no magnetic field, but when it is affected by magnetic fields such as magnets, the pattern will show rainbow color changes. This unique magnetochromic effect can be embedded in QR codes as a new anti-counterfeiting feature, combined with anti-counterfeiting technologies such as temperature change, relief, and fluorescence, to further improve the anti-counterfeiting ability of QR codes.

[0052] In some possible embodiments, based on the above embodiments, two photochromic dyes with different light response characteristics are used, namely, a photochromic dye A that changes from colorless to colored under ultraviolet light, and a photochromic dye B that changes from colored to colorless under visible light. Dyes A and B are added to the ink formula respectively, and two different optically variable inks are prepared by screen printing. The two-dimensional code pattern is first printed with the ink containing dye A, and then the hidden pattern is printed locally on the two-dimensional code with the ink containing dye B.

[0053] Dye A is colorless under normal conditions, becomes colored after being exposed to ultraviolet light, and returns to colorless after being exposed to visible light. Dye B is colored under normal conditions, becomes colorless after being exposed to visible light, and returns to color after the exposure stops. By utilizing the complementary light response characteristics of the two dyes, through zone printing, the local area of ​​the QR code can be made to appear and disappear under different lighting conditions.

[0054] Under normal conditions, the QR code only displays the normal QR code pattern, while the hidden pattern is invisible. However, under ultraviolet light, the hidden pattern area appears in color, contrasting with the QR code pattern. Under visible light, the QR code pattern and the hidden pattern disappear at the same time. This embedded hidden pattern gives the QR code dual photochromic properties, which can be used as a high-level hidden anti-counterfeiting technology, greatly increasing the difficulty of counterfeiting.

[0055] In some possible embodiments, based on the above embodiments, two fluorescent dyes with different emission wavelengths are selected, one is a neodymium dye that emits red fluorescence, and the other is a europium dye that emits green fluorescence. The two fluorescent dyes are compounded in a certain proportion and added to the ink formula of the present invention to prepare a fluorescent anti-counterfeiting ink. The two-dimensional code is printed with the ink. Under normal conditions, the two-dimensional code presents a normal black and white pattern, but under the excitation of ultraviolet light of a specific wavelength, it will emit red and green fluorescence.

[0056] Neodymium dyes and europium dyes are rare earth element dyes with unique 4f electron energy level transitions, which can emit fluorescence of characteristic wavelengths under ultraviolet light excitation. The emission wavelength of neodymium dyes is in the range of 580-660nm, showing red; the emission wavelength of europium dyes is in the range of 480-580nm, showing green. After the two dyes are compounded, they can emit dual-color fluorescence under the same ultraviolet light source.

[0057] The QR code printed with dual-band fluorescent ink does not show fluorescence under normal conditions, but emits red and green fluorescence at the same time under ultraviolet light of a specific wavelength (such as 365nm), forming a unique two-color anti-counterfeiting mark. This dual-band, two-color fluorescent feature is extremely difficult to copy and can effectively prevent the QR code from being counterfeited. At the same time, the fluorescent color is bright and the visual effect is outstanding, making it easy to identify and judge the authenticity.

[0058] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) The ink of the present invention uses thermochromic powder as a functional material and utilizes the reversible phase change effect of the pigment-long-chain alkane complex to give the ink a unique temperature-sensitive color-changing property. Thermochromic powder changes from colorless to colored at a specific temperature, and this color change process is reversible, and the color change effect is stable and long-lasting. By mixing three thermochromic powders with different color change temperatures and colors, the ink can present a variety of colors such as black, blue, and red at different temperatures, thereby realizing a multi-stage color change anti-counterfeiting function, greatly improving the anti-counterfeiting ability of the QR code;

[0060] (2) The ink of the present invention adds heat-expandable microcapsules as a foaming agent, which expands in volume when the ink is heated, forming a raised relief effect on the surface of the printed layer, which not only increases the anti-counterfeiting feature of the two-dimensional code, but also improves the touch and recognition of the two-dimensional code, and the anti-counterfeiting performance is more excellent;

[0061] (3) The ink of the present invention uses water-based acrylic acid and rosin resin as film-forming substances. The printed layer formed after drying is tough, wear-resistant, and has good adhesion, which can effectively protect the temperature-sensitive color-changing material of the inner layer; the acrylic ester polymer dispersant with both hydrophilicity and hydrophobicity is used to effectively disperse the toner and improve the dispersion stability and storage performance of the system;

[0062] (4) The ink of the present invention uses a silicone-modified polyacrylate leveling agent to form a lubricating layer with low surface tension on the surface of the ink, promote the spreading and wetting of the ink on the substrate, and improve the surface flatness and glossiness of the printed layer; add additives such as plasticizers, defoamers, and preservatives to further improve the flexibility, defoaming properties, and antibacterial properties of the ink, thereby optimizing the comprehensive performance of the ink;

[0063] (5) The ink of the present invention adopts an environmentally friendly water-based system with a low volatile organic compound (VOC) content and is environmentally friendly; the raw materials used are non-toxic and harmless and meet ROHS standards, and can be widely used in anti-counterfeiting of various products, especially in anti-counterfeiting packaging in the fields of food, medicine, daily chemicals, etc.;

[0064] (6) The preparation method provided by the present invention has a simple process and can be realized by using conventional dispersing, mixing, printing and other equipment. The production cost is low, batch production is possible, and the industrial application prospect is broad. The printed anti-counterfeiting two-dimensional code has excellent light resistance, wear resistance, water resistance, and solvent resistance, and the color change effect is long-lasting, and the anti-counterfeiting performance is outstanding, providing a higher level of anti-counterfeiting protection for the product.

[0065] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An anti-counterfeiting color-changing ink for a QR code, characterized in that: Its main components and weight parts are: 30-45 parts of thermochromic powder mixture, 60-80 parts of resin emulsion, 11-15 parts of dispersant, 22-35 parts of foaming agent, 3-5 parts of leveling agent, 3-8 parts of solvent, and 1-5 parts of auxiliary agent; the thermochromic powder mixture is obtained by mixing three thermochromic powders with different temperature sensing temperatures and different colors in the same proportion; the thermochromic powder is a reversible thermochromic powder that changes from colorless to colored at a specific temperature, has a color change temperature range of 5-50°C, and a particle size of 1-10μm.

2. The anti-counterfeiting color-changing ink for a two-dimensional code according to claim 1, characterized in that: The resin emulsion is obtained by mixing 30%-40% of water-based acrylic resin emulsion, 20%-40% of acrylic emulsion and 30%-40% of rosin resin emulsion; the total content of the water-based acrylic resin emulsion and the acrylic emulsion is 60%-80% of the total amount of the resin emulsion; the acid value of the rosin in the rosin resin emulsion is 150-200 mgKOH / g, and the softening point is 70-90°C.

3. The anti-counterfeiting color-changing ink for a two-dimensional code according to claim 2, characterized in that: The dispersant is an acrylic polymer, which is polymerized by alkyl methacrylate, hydroxyl-containing vinyl monomer and isobutyl methacrylate in a mass ratio of (50-80):(10-30):(10-20); the alkyl methacrylate is selected from one or more of methyl methacrylate, ethyl methacrylate and butyl methacrylate; the hydroxyl-containing vinyl monomer is selected from one or more of hydroxypropyl acrylate, hydroxyethyl acrylate and hydroxypropyl methacrylate.

4. The anti-counterfeiting color-changing ink for a two-dimensional code according to claim 3, characterized in that: The foaming agent is a heat-expandable microcapsule, the capsule wall of the heat-expandable microcapsule is an acrylamide-acrylonitrile copolymer, and a mixture of butane, pentane and dichloroethane is wrapped in the capsule wall, and the mass ratio of butane, pentane and dichloroethane is (20-50): (20-50): (20-40); the expansion temperature of the heat-expandable microcapsule is 80-120°C, and the diameter after expansion is 2-5 times the original diameter.

5. The anti-counterfeiting color-changing ink for a two-dimensional code according to claim 4, characterized in that: The leveling agent is silicone modified polyacrylate, wherein the mass ratio of the silicone modifier to the polyacrylate is (1-10): (100-80); the silicone modifier is selected from one or more of γ-aminopropyltriethoxysilane and γ-methacrylic acid oxypropyltrimethoxysilane.

6. The anti-counterfeiting color-changing ink for a two-dimensional code according to claim 5, characterized in that: The solvent is an alcoholic organic solvent with low toxicity and low volatility, preferably one or more of n-butanol and isopropanol; the boiling point of the alcoholic solvent is 100-150°C, and the solubility parameter is 10-14 (cal / cm 3 )^0.

5.

7. The anti-counterfeiting color-changing ink for a two-dimensional code according to claim 6, characterized in that: The auxiliary agent includes a plasticizer, a defoamer and a bactericidal preservative, wherein the plasticizer is selected from one or more of dibutyl phthalate and dioctyl phthalate, and the amount used is 0.5-2% of the total amount of ink; the defoamer is selected from one or more of polyether modified polysiloxane and organic siloxane, and the amount used is 0.2-1% of the total amount of ink; The bactericidal preservative is selected from one or more of 1,2-benzisothiazolin-3-one and 2-hydroxypyridine-N-oxide, and the amount used is 0.1-0.5% of the total amount of ink.

8. The anti-counterfeiting color-changing ink for a two-dimensional code according to any one of claims 1 to 7, characterized in that: The ink is printed on the surface of the QR code by screen printing, with a screen number of 250-400 lines / inch and a mesh rate of 30-50%; the thickness of the printed layer is 10-30 μm; After printing, the product is dried naturally or with hot air at 40-60°C for 2-10 minutes to obtain an anti-counterfeiting two-dimensional code with a temperature-variable pattern, wherein the color of the pattern can be reversibly changed with temperature.

9. A method for preparing an anti-counterfeiting two-dimensional code, characterized in that: The following steps are involved: (1) printing the anti-counterfeiting color-changing ink according to any one of claims 1 to 8 evenly on the surface of the two-dimensional code, with a printing layer thickness of 10 to 30 μm; (2) The two-dimensional code printed in step (1) is dried naturally or dried with hot air at 40-60° C. for 2-10 min to obtain an anti-counterfeiting two-dimensional code with a temperature-dependent pattern.

10. The method for preparing an anti-counterfeiting two-dimensional code according to claim 9, characterized in that: In the step (1), a screen printing process is adopted, the number of screen lines used is 250-400 lines / inch, and the mesh rate is 30-50%; the tension between the screen and the surface of the two-dimensional code during printing is 10-30N / cm, the hardness of the scraper is 60-80 degrees, and the scraper printing speed is 0.1-1m / s.