Water-based optically variable anti-counterfeiting coating

Abstract

The invention discloses a water-based optically variable anti-counterfeiting coating which comprises the following components in parts by weight: 60-150 parts of a water-based film-forming coating and 0.1-1 part of water-based optically variable color paste, mixing and dispersing: mixing the water-based film-forming coating and the water-based photochromic slurry in proportion, and then dispersing at a high speed; post-treatment: standing for 1 hour, and curing to obtain the water-based optically variable anti-counterfeiting coating. According to the invention, water is used as a main dispersion medium, the VOC content is extremely low, the paint is nontoxic and non-combustible, the requirements of green production and sustainable development are met, and the construction environment is improved; the special optically variable pigment protected by the patent is adopted, the special optically variable pigment has excellent compatibility with the specific water-based paint and auxiliary agent system, stable dispersion and good orientation of the multi-layer optical film pigment in the water-based system are ensured, and a dried coating is high in visual impact, high in public recognition degree and difficult to copy; through an optimized formula and a dispersion process, the problem that the optically variable pigment in the patent is easy to settle and agglomerate in a water-based system is solved, the product is stable to store, and the coating performance is lasting after construction.

Description

Technical Field

[0001] This invention belongs to the field of anti-counterfeiting materials technology, specifically relating to a water-based optically variable anti-counterfeiting coating. Background Technology

[0002] With the rapid development of the market economy, anti-counterfeiting technology plays a vital role in people's lives and various industries. Currently, commonly used anti-counterfeiting methods include QR codes, holographic labels, and thermochromic inks. With the development of the times and the advancement of technology, photochromic materials, due to their unique perspective or light-dependent color-changing characteristics, have been applied to the anti-counterfeiting field, creating optical color-changing anti-counterfeiting technology. The application of optical color-changing anti-counterfeiting technology is not only a challenge of the technological era but also an opportunity for integrated development. Optical color-changing coatings are anti-counterfeiting coatings that utilize the reflection and refraction of light by photochromic pigments in the coating to produce color. Because optical color-changing coatings have specific pearlescent and metallic effects, even high-resolution electronic scanners cannot achieve ideal scanning results, and ordinary color copiers cannot reproduce them, thus optical color-changing coatings have effective anti-counterfeiting properties. When an observer views the image from a 0° angle directly and from a 60° oblique angle, the text and images printed with the photochromic coating will present a pair of different colors, such as magenta-blue, green-blue, and cyan-green. Therefore, optical color-changing anti-counterfeiting technology is highly favored due to its high technical threshold, difficulty in counterfeiting, and intuitive identification. Traditional optical color-changing coatings are mostly based on multilayer optical thin-film pigments (commonly known as chameleon pigments), but these coatings are mostly solvent-based systems containing a large amount of volatile organic compounds, which can cause environmental pollution, flammability hazards, and potential health risks to operators during production, construction, and subsequent use. Water-based coatings, with their advantages of being environmentally friendly and having low VOC emissions, have become a green coating trend, but when directly combined with optical color-changing coatings, they are prone to defects such as uneven dispersion and poor stability. This invention aims to solve the above problems by using a special structured optical color-changing pigment, through a specific water-based formulation system and process, to prepare a water-based anti-counterfeiting coating that combines excellent environmental friendliness, stability, and a strong dynamic color-changing effect. Summary of the Invention

[0003] The purpose of this invention is to provide a water-based optically variable anti-counterfeiting coating to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a water-based photochromic anti-counterfeiting coating, comprising, by weight, 60-150 parts of water-based film-forming coating and 0.1-1 parts of water-based photochromic color paste.

[0005] Preferably, the aqueous photochromic paste is prepared by the following method:

[0006] ①Raw material preparation: 30-50 parts of photochromic pigment, 1-4 parts of dispersant, 1-4 parts of defoamer, and 30-50 parts of deionized water; wherein the photochromic pigment is the photochromic pigment prepared according to the invention patent [CN115469388B]; the dispersant is a high molecular weight block copolymer solution containing pigment affinity groups; and the defoamer is a polyether-modified polysiloxane solution.

[0007] ② Mixing and Dispersion: Mix the photochromic pigment, dispersant, defoamer, and deionized water in a certain proportion, and then disperse the mixture in a high-speed mixer at a speed of 2000-5000 rpm for 15-30 minutes to form a preliminary slurry;

[0008] ③ Stepwise grinding: The initially mixed and dispersed slurry is placed in a sand mill containing coarse-sized zirconia beads and ground for 10-15 minutes; then the ground mixture is transferred to a sand mill containing fine-sized zirconia beads and ground for another 10-15 minutes. Stepwise grinding can effectively control the grinding time at each stage, avoiding performance damage to the photochromic pigments caused by prolonged grinding in a single step; stepwise grinding can efficiently control particle size distribution, ensuring the particle size requirements of water-based photochromic pigments; stepwise grinding can efficiently break up agglomerates, allowing the additives to fully function.

[0009] ④ Filtration: After filtration through a 200-mesh sieve, a water-based photochromic pulp with a particle size D50≤20um is obtained;

[0010] Preferably, the waterborne film-forming coating is an environmentally friendly waterborne resin, selected from at least one of waterborne acrylic resin, waterborne polyurethane resin, or mixtures thereof.

[0011] Preferably, the mixing mass ratio of water-based photochromic paste to water-based film-forming coating is 1:(100-1500).

[0012] Preferably, a method for preparing the water-based optically variable anti-counterfeiting coating includes the following steps:

[0013] ①: Mix the light-changing pigment paste and the water-based film-forming coating, and disperse them at high speed for 30-60 minutes;

[0014] ②: After standing and maturing for 1 hour, the water-based photochromic anti-counterfeiting coating is obtained.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] Environmentally friendly and safe: Using water as the dispersion medium fundamentally solves the environmental and safety problems of solvent-based coatings;

[0017] Excellent anti-counterfeiting performance: It adopts a special photochromic pigment with patent protection, which has excellent compatibility with the specific water-based resin and additive system of this invention. This ensures the stable dispersion and good orientation of the multilayer optical film pigment in the water-based system, so that the dried coating has a bright and dynamic color-changing effect with strong visual impact, high public recognition, and difficulty in being copied.

[0018] Good stability: Through optimized formulation and dispersion process, the problem of easy sedimentation and agglomeration of patented photochromic pigments in water-based systems has been solved. The product is stable during storage and the coating performance is long-lasting after application. Attached Figure Description

[0019] Figure 1 This is a flowchart of the water-based photochromic anti-counterfeiting coating of the present invention.

[0020] Figure 2 This is a schematic diagram showing the optical effects of cardstock printed with the coating of this invention from different viewing angles.

[0021] Figure 3 This is a schematic diagram showing the optical effect of a backing paper coated with the coating of the present invention at different viewing angles. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] Please see Figure 1-3 This is the first embodiment of the present invention, which provides a water-based optically variable anti-counterfeiting coating, comprising the following steps:

[0025] 1. Take 150 grams of water-based acrylic resin (solid content approximately 45%).

[0026] 2. Add 1 gram of water-based photochromic paste (solid content approximately 45%, containing green-to-purple-red photochromic pigment).

[0027] 3. Stir and mix at 300-500 rpm for 30 minutes.

[0028] 4. After standing and maturing for 1 hour, a water-based optically variable anti-counterfeiting coating suitable for screen printing is obtained.

[0029] When the coating is printed on cardstock and dried, the cardstock exhibits a smooth gradient between green and purple under different viewing angles, providing a significant anti-counterfeiting effect.

[0030] Example 2

[0031] This is a second embodiment of the present invention, which provides a water-based optically variable anti-counterfeiting coating, comprising the following steps:

[0032] 1. Take 150 grams of waterborne polyurethane resin (solid content approximately 45%).

[0033] 2. Add 0.2 grams of water-based photochromic paste (solid content approximately 45%, containing transparent red-to-green pigment).

[0034] 3. Stir and mix at a speed of 400-600 rpm for 30 minutes.

[0035] 4. After standing and maturing for 1 hour, a water-based optically variable anti-counterfeiting coating that can be applied to the backing paper is obtained.

[0036] The dried coating has excellent adhesion and abrasion resistance, and exhibits a red-to-green transparent effect.

[0037] Table 1: Performance Test Table of Water-based Optically Modifiable Anti-counterfeiting Coating

[0038] Test Project Test methods Example 1 Example 2 Adhesion Cross-cut test (1mm spacing), peeling tape, assess the area of ​​detachment. Grade 0 (The cut edges are completely smooth, with no chips falling off). Grade 0 (The cut edges are completely smooth, with no chips falling off). abrasion resistance The mass loss was measured by rubbing the coating with a rotating rubber grinding wheel a specified number of times under a specific pressure. Mass loss: 12mg (500 rpm, 750g load) Mass loss: 8 mg (500 rpm, 750 g load) Color difference value ΔE (the larger the ΔE value, the more obvious the color change effect and the stronger the visual impact). Using a colorimeter, calculate the color difference ΔE between two standard observation angles (e.g., 15° incident, measuring the chromaticity values ​​L*, a*, b* at 0° (normal) and 45° viewing angles respectively). ΔE≥80 (from green at the normal angle to magenta at the lateral angle) —

[0039] Although embodiments of the invention have been shown and described in detail above, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water-based optically variable anti-counterfeiting coating, characterized in that, By weight, it includes: 60-150 parts of water-based film-forming coating and 0.1-1 parts of water-based photochromic paste.

2. The water-based optically variable anti-counterfeiting coating according to claim 1, characterized in that, The aqueous photochromic paste is prepared by the following method: S1: Raw material preparation: 30-50 parts of photochromic pigment, 1-4 parts of dispersant, 1-4 parts of defoamer and 30-50 parts of deionized water; S2: Mixing and Dispersion: Mix the photochromic pigment, dispersant, defoamer, and deionized water in a certain proportion and disperse them in a high-speed mixer at a speed of 2000-5000 rpm for 15-30 minutes to form a preliminary slurry; S3: Stepwise grinding: Put the mixed and dispersed preliminary slurry into a sand mill containing coarse-diameter zirconia beads and grind for 10-15 minutes; then transfer the ground mixture to a sand mill containing fine-diameter zirconia beads and grind for 10-15 minutes. Through step-by-step grinding, the particle size distribution can be controlled to ensure the particle size requirements of water-based photochromic pastes; step-by-step grinding can efficiently break up agglomerates and allow the additives to work fully. S4: Filtration: After filtration through a 200-mesh sieve, a water-based photochromic pulp with a particle size D50≤20um is obtained.

3. The water-based optically variable anti-counterfeiting coating according to claim 2, characterized in that, The dispersant is a high molecular weight block copolymer solution containing affinity pigment groups; the defoamer is a polyether-modified polysiloxane solution.

4. The water-based optically variable anti-counterfeiting coating according to claim 1, characterized in that, The waterborne film-forming coating is any one of waterborne acrylic resin and waterborne polyurethane resin, or a mixture of both.

5. The water-based optically variable anti-counterfeiting coating according to claim 1, characterized in that, The mass ratio of the photochromic pigment paste to the water-based film-forming coating is 1:(100-1500).

6. A water-based optically variable anti-counterfeiting coating according to any one of claims 1-5, characterized in that, Its preparation method: Step 1: Mix the light-changing pigment paste and the water-based film-forming coating, and disperse them at high speed for 30-60 minutes; Step 2: After standing and maturing for 1 hour, the water-based photochromic anti-counterfeiting coating is obtained.

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