Water-based wear-resistant ink and preparation method thereof

Abstract

The invention discloses water-based wear-resistant ink and a preparation method thereof, and belongs to the technical field of ink. The ink is prepared from the following components in parts by weight: 20 to 35 parts of waterborne polyurethane resin, 15 to 25 parts of waterborne acrylic resin with an acid value of 40 to 80 mg KOH / g, 5 to 15 parts of KH570 silane coupling agent modified nano aluminum oxide, 3 to 8 parts of polyethylene wax emulsion, 10 to 20 parts of pigment and auxiliaries. The preparation method comprises the following steps: firstly, carrying out surface modification on the nano aluminum oxide by using KH570, and then mixing, dispersing and grinding all the components. Through the synergistic effect of the acrylic resin with a specific acid value and the modified nano aluminum oxide, the problem that nano particles are easy to agglomerate in a system is solved, the nano particles can be stably dispersed, and the interface bonding with the resin is enhanced, so that the ink is endowed with excellent adhesive force, wear resistance and storage stability while the process is simplified and the cost is reduced; the BOPP film packaging material is especially suitable for BOPP film packaging materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ink, in particular to a water-based ink with excellent adhesion and wear resistance and a preparation method thereof, which is especially suitable for difficult-to-adhere plastic substrates such as BOPP film. BACKGROUND

[0002] Water-based ink is increasingly widely used in the field of packaging printing due to its environmental protection and safety. However, the poor adhesion of water-based systems on non-polar plastic substrates (such as BOPP) and the wear resistance that is usually not as good as that of solvent-based ink are two major technical bottlenecks restricting its development.

[0003] To improve wear resistance, the prior art usually adopts the method of adding wear-resistant fillers (such as nano-alumina and silicon dioxide) or wear-resistant additives (such as polyethylene wax and polytetrafluoroethylene wax). For example, patent document CN104151921A discloses a "double-doping" method for improving the wear resistance of water-based ink by adding nano-alumina and polyethylene wax emulsion. However, nano-fillers have a large specific surface area and high surface energy, and are prone to agglomeration in water-based systems, resulting in uneven dispersion, making it difficult to fully exert the wear-resistant reinforcing effect, and possibly damaging the leveling property and gloss of the ink, and even causing storage sedimentation problems.

[0004] To further solve the dispersion and performance coordination problems, some solutions use more complex technologies. For example, patent document CN118165571B discloses a wear-resistant component with an "ABA type" multi-branched structure prepared by atom transfer radical polymerization (ATRP) technology using octachloropropyl cage silsesquioxane as an initiator. Although this solution can achieve excellent performance, the preparation process is complicated, the reaction conditions are harsh, and the raw material cost is high, which greatly limits its industrial production and application.

[0005] Therefore, there is an urgent need in the art for a new technical solution that can ensure excellent wear resistance and adhesion while taking into account the simplicity of the formula, the feasibility of the cost, and the convenience of production. SUMMARY

[0006] 1. Technical problem to be solved: The purpose of the present application is to overcome the shortcomings of the prior art and provide a water-based wear-resistant ink and a preparation method thereof. The ink realizes efficient and stable dispersion of nano-fillers by selecting components and utilizing their synergistic effect, thereby achieving excellent wear resistance, adhesion, and storage stability, and the preparation process is simple and the cost is controllable.

[0007] 2. Technical solution: To solve the above problems, the present application adopts the following technical solution.

[0008] The present application provides a kind of water-based wear-resistant ink, by parts by weight, comprising the following components: Water-based polyurethane resin 20-35 parts; Water-based acrylic resin 15-25 parts, the acid value of the water-based acrylic resin is 40-80 mg KOH / g; Silane coupling agent modified nano alumina 5-15 parts, the silane coupling agent is KH570; Polyethylene wax emulsion 3-8 parts; Pigment 10-20 parts; Dispersant 0.5-2 parts; Defoaming agent 0.3-1 part; Leveling agent 0.5-2 parts; Deionized water 30-50 parts.

[0009] Preferably, the silane coupling agent modified nano alumina is prepared by a method comprising the following steps: dispersing nano alumina in an aqueous ethanol solution, adding KH570, refluxing at 70-90℃ for 1-3 hours, wherein the mass ratio of nano alumina to KH570 is 1:(0.5-1). Further, after the reaction, it is filtered, washed, and dried at 60-80℃.

[0010] Preferably, the water-based polyurethane resin is an aliphatic polyurethane dispersion with a solid content of 30%-40%. The glass transition temperature (Tg) of the water-based acrylic resin is 30-60℃, and its acid value is preferably 50-70 mg KOH / g.

[0011] The present application provides a preparation method of the above-mentioned water-based wear-resistant ink, comprising the following steps: S1, preparing silane coupling agent modified nano alumina; S2, mixing water-based polyurethane resin, water-based acrylic resin, polyethylene wax emulsion, dispersant, defoaming agent and deionized water, and high-speed dispersing at a speed of 400-800 r / min for 30-60 minutes to prepare a mixed emulsion; S3, adding silane coupling agent modified nano alumina, pigment and leveling agent obtained in step S1 to the mixed emulsion, stirring uniformly, and then transferring to a sand mill, using zirconium oxide beads as grinding medium, grinding at a speed of 1000-1500 r / min to a fineness of ≤15 μm, and filtering the product.

[0012] The present application provides an article having a coating formed by printing or coating the above-mentioned water-based wear-resistant ink on its surface. The article is preferably a BOPP film packaging material.

[0013] 3. Beneficial effects: Compared with the prior art, the technical scheme provided by the application has the following beneficial effects: (1) Synergistic effect: by using water-based acrylic resin with a specific acid value (40-80 mg KOH / g) and KH570 modified nano-alumina, it is found that there is a synergistic effect between the two. The carboxyl group of the acrylic resin and the KH570 ester group on the surface of the modified alumina, as well as the polyurethane molecular chain, can form a strong interfacial bond, which not only solves the problem of agglomeration and sedimentation of nanoparticles, but also makes them uniformly dispersed to maximize the wear resistance, and significantly enhances the adhesion of the ink coating to the substrate (especially BOPP).

[0014] (2) Triple wear-resistant mechanism: a multi-scale synergistic wear-resistant system of "modified nano-alumina (microscopic hard wear-resistant) + polyethylene wax (macroscopic lubricating wear-resistant) + strong and tough resin matrix (interfacial bonding enhancement)" is constructed, and the comprehensive wear resistance is superior.

[0015] (3) Simple process, obvious cost advantage: the application discards the complex polymer synthesis and uses conventional raw materials and simple physical mixing and grinding process, which greatly reduces the production cost and process difficulty while obtaining performance close to or even partially surpassing complex technology (such as CN118165571B), and is very suitable for industrial large-scale production.

[0016] (4) Good storage stability: due to the effective stabilization of the nano-filler, the ink system is not prone to sedimentation and caking, and the storage stability is significantly improved.

[0017] It should be noted that the structures not introduced by the application do not involve the design points and improvement direction of the application, and are the same as or can be realized by the prior art, and are not described here. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a comparison column chart of the wear resistance test results of the inks prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the application. DETAILED DESCRIPTION

[0019] The application will be described in detail below through specific examples, so that those skilled in the art can more fully understand the application. In the following examples, if not otherwise specified, the raw materials used can be obtained by commercial means.

[0020] Example 1: Preparation of silane coupling agent modified nano-alumina Take 15 g of nano-alumina with an average particle size of 30 nm, disperse in 100 mL of 60% volume fraction of ethanol aqueous solution, ultrasonic treatment for 20 minutes. Then add 10 g of silane coupling agent KH570 (γ- (methacryloyloxy) propyl trimethoxysilane), heat reflux reaction at 80°C for 2 hours. After the reaction is completed, perform suction filtration, wash with anhydrous ethanol 3 times to remove unreacted coupling agent, place the filter cake in a 80°C air drying oven for drying for 4 hours, take out and lightly grind to obtain KH570 modified nano-alumina powder.

[0021] Example 2: Preparation of water-based wear-resistant ink (optimal ratio) According to the ratio shown in Table 1, weigh each component.

[0022] Table 1: Ink formula of Example 2 (parts by weight)

[0023] Preparation method: 1. Add water-based polyurethane resin, water-based acrylic resin, polyethylene wax emulsion, dispersant, defoamer and deionized water into the stirring kettle.

[0024] 2. Stir and disperse at a speed of 600 r / min for 45 minutes to obtain a uniform mixed emulsion.

[0025] 3. Add the modified nano-alumina prepared in Example 1, phthalocyanine blue pigment and leveling agent to the mixed emulsion.

[0026] 4. Continue to stir and mix at 300 r / min for 30 minutes to ensure that all components are initially mixed uniformly.

[0027] 5. Transfer the mixture to a vertical sand mill, add an equal volume of zirconia beads (particle size 1.0 mm), and grind at a speed of 1200 r / min for 2 hours.

[0028] 6. After grinding, filter with a 200 mesh screen to remove the grinding medium, and obtain the blue water-based wear-resistant ink.

[0029] Examples 3-4: Inks with different amounts of modified nano-alumina The preparation method is exactly the same as Example 2, only the amount of modified nano-alumina in Example 1 is changed, specifically: Example 3: The amount of modified nano-alumina is 5 parts.

[0030] Example 4: The amount of modified nano-alumina is 15 parts.

[0031] Comparative Example 1: Unmodified nano-alumina The preparation method is completely the same as that of Example 2, except that the modified nano-alumina of Example 1 is not used, but an equal amount of nano-alumina which is not treated with KH570 is directly used.

[0032] Comparative Example 2: aqueous acrylic resin with too low acid value The preparation method is completely the same as that of Example 2, except that the aqueous acrylic resin is replaced by a type with an acid value lower than 20 mg KOH / g (such as Celocor AF 6000 of Arkema).

[0033] Comparative Example 3: without polyethylene wax emulsion The preparation method is completely the same as that of Example 2, except that the polyethylene wax emulsion is not added.

[0034] Then, the inks prepared in the above examples and comparative examples are uniformly coated on a BOPP film treated by corona discharge using a wire bar coater, dried in an oven at 80°C for 3 minutes to form an ink layer with a dry film thickness of about 10 μm. The performance tests are carried out according to the following standards: Adhesion: GB / T 13217.7-2009, grid method (1 mm x 1 mm), 0 best, 5 worst.

[0035] Abrasion resistance: RCA abrasion tester is used (according to standard method), load 175 g, and the number of rubbings when the ink layer is worn out to expose the substrate is recorded.

[0036] Storage stability: the ink is sealed and stored in a constant temperature oven at 50°C for 7 days, and after returning to room temperature, the viscosity change rate is tested, and the state is observed.

[0037] The test results are summarized in Table 2.

[0038] Table 2: Performance test results

[0039] In summary, in the present application: Example 2 vs. Comparative Example 1: Example 2 uses KH570 modified nano-alumina, and the adhesion (0 level) and abrasion resistance (650 times) are much better than those of Comparative Example 1 (2 level, 380 times). This proves that the KH570 modification plays a decisive role in improving the dispersibility of nano-alumina and improving the adhesion and abrasion resistance. The sedimentation of Comparative Example 1 also shows that the unmodified nanoparticles cannot stably exist in the system.

[0040] Example 2 vs. Comparative Example 2: Comparative Example 2 has a lower acid value of the acrylic resin, which results in insufficient amount of carboxyl groups and weak interaction with modified nano-alumina and the substrate, leading to significant decrease in adhesion and abrasion resistance. This proves that the waterborne acrylic resin with a specific acid value range (40-80 mg KOH / g) is the key to achieve the synergistic effect.

[0041] Example 2 vs. Comparative Example 3: Comparative Example 3 has a significant decrease in abrasion resistance (450 times vs. 650 times) due to the lack of lubrication of polyethylene wax, proving the indispensable contribution of polyethylene wax in the triple abrasion resistance system of the present application.

[0042] Example 2, 3, 4 comparison: With the increase of the amount of modified nano-alumina, the abrasion resistance is improved, but excessive amount (15 parts) may lead to incomplete resin coating, slightly affecting the adhesion and causing the viscosity to grow slightly faster. It shows that the use amount of 5-15 parts is the best balance point of the comprehensive performance.

[0043] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A water-based abrasion-resistant ink, characterized in that, By weight, it includes the following components: 20-35 parts of waterborne polyurethane resin; 15-25 parts of waterborne acrylic resin, wherein the acid value of the waterborne acrylic resin is 40-80 mg KOH / g; 5-15 parts of nano-alumina modified with silane coupling agent, wherein the silane coupling agent is KH570; 3-8 parts of polyethylene wax emulsion; 10-20 parts pigment; Dispersant 0.5-2 parts; 0.3-1 part defoamer; Leveling agent 0.5-2 parts; 30-50 parts deionized water.

2. The water-based abrasion-resistant ink according to claim 1, characterized in that, The silane coupling agent modified nano-alumina is prepared by a method comprising the following steps: dispersing nano-alumina in an aqueous ethanol solution, adding KH570, and refluxing at 70-90°C for 1-3 hours, wherein the mass ratio of nano-alumina to KH570 is 1:(0.5-1).

3. The water-based abrasion-resistant ink according to claim 2, characterized in that: After the reflux reaction, the process also includes filtration, washing, and drying steps, with the drying temperature being 60-80℃.

4. The water-based abrasion-resistant ink according to claim 1, characterized in that: The waterborne polyurethane resin is an aliphatic polyurethane dispersion with a solid content of 30%-40%; the waterborne acrylic resin has a glass transition temperature of 30-60℃.

5. The water-based abrasion-resistant ink according to claim 1, characterized in that: The acid value of the waterborne acrylic resin is 50-70 mg KOH / g.

6. A method for preparing the water-based abrasion-resistant ink as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of silane coupling agent modified nano-alumina; S2. Waterborne polyurethane resin, waterborne acrylic resin, polyethylene wax emulsion, dispersant, defoamer and deionized water are mixed and dispersed at high speed to obtain a mixed emulsion. S3. Add the silane coupling agent modified nano-alumina, pigment, and leveling agent obtained in step S1 to the mixed emulsion, stir evenly, grind to a fineness of ≤15μm, and filter out the material.

7. The method for preparing water-based abrasion-resistant ink according to claim 6, characterized in that: In step S2, the high-speed dispersion rotation speed is 400-800 r / min, and the dispersion time is 30-60 minutes.

8. The method for preparing water-based abrasion-resistant ink according to claim 6, characterized in that: In step S3, the grinding is carried out using a sand mill with zirconia beads as the grinding medium and a grinding speed of 1000-1500 r / min.

9. An article, characterized in that, A coating formed by printing or coating the surface with the water-based abrasion-resistant ink as described in any one of claims 1-5.

10. The article according to claim 9, characterized in that: The product in question is a BOPP film packaging material.

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