A water-based coating solution for vacuum aluminum plating for paper printing, a preparation method thereof, and application thereof

Abstract

The application discloses a kind of paper printing vacuum aluminum plating water-based coating liquid.The coating liquid includes low Tg / high hardness water-based acrylic emulsion and polycarbonate type and / or acrylic modified water-based polyurethane dispersion as film-forming material, with water-based auxiliary agent, film-forming auxiliary agent, wax emulsion, water and other substances.Low Tg / high hardness water-based acrylic emulsion is to use alkali-soluble acrylic ester solid resin selected under specific condition as reactive macromolecular rheological control emulsifier, and to use seed emulsion polymerization method to synthesize core-shell structure of styrene-acrylic emulsion.The coating liquid of the application has excellent rheological property, excellent sealing property and film-forming property, super-high aluminum plating gloss, wear resistance, excellent anti-sticking and anti-glare property, chemical resistance, resolubility, printing adaptability, environmental protection, and is suitable for various printing and coating methods, especially suitable for printing industry of tobacco and liquor with extremely strict requirements on printing speed, drying speed, wear resistance, anti-sticking and aluminum plating appearance.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation technology, specifically relating to a vacuum aluminizing aqueous coating liquid for paper printing, its preparation method, and its application. Background Technology

[0002] Currently, with the increasing environmental awareness and the implementation of various laws and regulations worldwide, green production, green packaging, green consumption, and the circular economy have become the pursuit of various industries and enterprises. At present, the printing and packaging industries are implementing these green concepts, with lightweight packaging, reduced material usage, material diversification, aluminum reduction / reduction, PVDC elimination, PVC elimination, recyclability, and biodegradability gradually gaining popularity and acceptance within the industry.

[0003] Paper-based packaging often fails to meet the barrier properties (oxygen barrier, water barrier, moisture barrier, etc.) required for food packaging applications. Currently, a common approach is to laminate paper with aluminum foil to achieve these barrier properties. Based on different manufacturing processes, it can be divided into three types: aluminum foil composite paper, vacuum metallized paper, and transfer metallized paper. Compared to aluminum foil composite paper, metallized paper offers both cost reduction and energy-saving and environmentally friendly advantages, aligning better with the development trend of the packaging paper industry. It has become a major trend in labeling, tobacco and alcohol labels, food, daily chemical products, and gift box packaging.

[0004] With industry development, social demand, and technological advancements, vacuum metallization has become increasingly popular in the printing and packaging industries due to its stable and reliable printing performance, excellent moisture-proof and moisture-retaining properties, low aluminum usage, and environmentally friendly properties such as biodegradability and recyclability. Its application range is also expanding.

[0005] Direct metallization involves applying a special primer coating to the surface of the paper, followed by vacuum metallization, which deposits aluminum molecules onto the paper surface to form metallized paper. To address the roughness of the paper surface and the unevenness of the aluminum coating in direct metallization, the paper needs to undergo ultra-calendering and / or pre-treatment with a primer varnish to fill the micropores or fibrous structures on the paper surface.

[0006] It is important to emphasize that the paper currently used for direct metallization is basically imported special paper. Ordinary paper that has not undergone high-pressure treatment has a rough and loose surface fiber structure. Conventional direct metallization primer coating resins have poor surface film formation and shaping, strong penetration and good leveling. This results in serious problems such as loss of gloss and graying of the metallized surface, and it is impossible to obtain good metallization effect and durability.

[0007] Currently, pretreatment primers are mostly solvent-based coatings or mixtures of various water-based resins. Solvent-based coatings are volatile, flammable, and explosive, and can irritate the respiratory tract and eyes, causing discomfort to construction workers. Therefore, they are not recommended from an environmental and safety perspective. While conventional water-based resins are superior in terms of safety, environmental protection, and green production, their primers suffer from poor penetration, compatibility, durability, and aluminum plating effect. Therefore, the industry is seeking and developing environmentally friendly, aluminum-plating-friendly, and durable pretreatment water-based primers.

[0008] Patent CN 103410047 A discloses "a water-soluble varnish for coating the surface of aluminum-plated inner lining paper for cigarette packs". This patent has solved the problems of wear resistance, abrasion resistance, folding resistance and surface smoothness of the inner lining paper for cigarette packs to a certain extent. However, it has the following problems: the selected resin is a mixture of water-soluble styrene-acrylic acid copolymer and water-soluble butyl acrylate-styrene copolymer, which has compatibility problems. In addition, a large amount of ethanol is used as a co-solvent, which is uneconomical and environmentally unfriendly. It does not mention the properties such as gloss, chemical resistance and anti-blocking.

[0009] Patent CN 103866607 A discloses "a high-strength direct aluminum plating water-based primer and its preparation method and application". This patent solves the problems of sealing, flexibility and high metallic texture of aluminum-plated paper. However, it requires different types of resins (polyurethane, acrylic, polyester, etc.) combined with crosslinking agents (amino resin, isocyanate curing agent, aziridine, carbodiimide, etc.). It needs to be prepared on the spot, which has incompatibility problems. Moreover, the pre-treated primer needs to be cured for a long time before aluminum plating can be done. For printing and coating, the efficiency is too low.

[0010] Patent CN 110167993 A discloses "emulsion particles, emulsion containing the same, and method for preparing the emulsion". This patent adopts a core-shell four-layer structure in terms of technical route. It improves the film performance and durability that are difficult to achieve in the prior art by using different glass transition temperatures. However, it does not mention the properties of direct-coated paper such as gloss, adhesion, chemical resistance and printability.

[0011] Patent CN 105568758 A discloses "an aqueous direct-coating primer for ordinary transfer paper and its preparation method." This invention uses polyvinyl alcohol to coat a large amount of silica sol, forming a network structure through cross-linking of polyvinyl alcohol and boric acid. The silica sol fills the network, achieving the purpose of sealing the uncoated backing paper. Boric acid can only cross-link with polyvinyl alcohol during high-temperature drying, eliminating the need for a two-component formulation. The addition of acrylic acid achieves high aluminum plating brightness. This allows ordinary uncoated backing paper to be used in direct-coating backing paper products, thereby reducing costs.

[0012] This invention aims to solve the above problems by developing a water-based primer resin that can be used for vacuum metallization on ordinary direct-coated paper. It has excellent sealing and film-forming properties, ultra-high metallization gloss, excellent anti-staining properties, abrasion resistance, printability, and environmental friendliness, and can achieve the same direct-coating effect as direct-coated supercalendered paper. Summary of the Invention

[0013] In view of this, and addressing the industry challenges encountered in the future development trends of the circular economy and paper-based packaging (aluminization / reduction of aluminum, recyclability, and biodegradability), the purpose of this invention is to provide a water-based vacuum metallizing coating liquid for paper printing. This liquid can achieve the same direct-coating effect and durability as direct-coated supercalendered paper simply by applying it to uncalendered paper materials. It is convenient to use and simple to apply. The coating liquid of this invention possesses excellent sealing and film-forming properties, ultra-high aluminum gloss, excellent anti-sticking properties, abrasion resistance, resolubility, printability, and environmental friendliness. It can achieve the same direct-coating effect as direct-coated supercalendered paper, effectively accelerating the water-based coating process and promoting the industry's "low-carbon" green development.

[0014] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0015] A vacuum metallizing aqueous coating liquid for paper printing comprises the following raw materials by weight percentage:

[0016] Aqueous acrylic emulsion, 50-75%, preferably 55-70%.

[0017] The aqueous polyurethane dispersion comprises 5-20%, preferably 5-15%.

[0018] Deionized water 10-30%, preferably 10-25%.

[0019] The wax emulsion content is 2-5%, preferably 2.5-4.5%.

[0020] Defoamer 0.1-0.5%, preferably 0.2-0.4%,

[0021] The wetting agent is 0.5-1.5%, preferably 0.5-1.0%.

[0022] Film-forming aid 0-3%, preferably 0-2%,

[0023] The fast-drying solvent is 7-25%, preferably 10-20%.

[0024] In this invention, the aqueous acrylic emulsion is an aqueous acrylic emulsion with a core-shell structure, an acid value of 20-70 mg KOH / g, and a solid content of 40-50 wt%. Preferably, the glass transition temperature (Tg) of the core is -30-20℃ (e.g., -25℃, -20℃, -15℃, 5℃, 15℃, etc.), the glass transition temperature (Tg) of the shell is 85-120℃ (e.g., 90℃, 95℃, 100℃, 110℃, 115℃, etc.), the core / shell mass ratio is 50 / 50-70 / 30, and the particle size range is 50-80 nm.

[0025] In a preferred embodiment, the aqueous acrylic emulsion of the present invention is a core-shell styrene-acrylic emulsion synthesized by seed emulsion polymerization using a specifically selected alkali-soluble acrylate solid resin as a reactive macromolecular rheology-controlled emulsifier. The specifically selected alkali-soluble acrylate solid resin is a styrene-acrylic resin and / or maleic anhydride-modified styrene-acrylic resin with an acid value of 200–300 mg KOH / g, a molecular weight Mw of 7500–16000 g / mol, a molecular weight distribution PDI of 1.4–2.0, and a glass transition temperature Tg of 80–120 °C.

[0026] This invention uses alkali-soluble acrylic resin as a rheology-controlled emulsifier during the shell and core layer emulsion polymerization, resulting in better polymerization stability and storage stability. The emulsion rheology is close to that of a Newtonian fluid, allowing it to quickly level and wet the substrate after being formulated into a coating solution, filling all the fibers of the paper. The resin contains a large number of carboxyl groups that can combine with the paper fibers to form hydrogen bonds. In addition, the emulsion has a narrow particle size distribution and small particle size. The synergy of these factors can achieve the same direct coating effect as direct-coated supercalendered paper (high gloss and good transparency). Because the emulsion has a core-shell structure and a high content of carboxyl groups, the coating solution can achieve a fast drying speed and hardness build-up at a low film-forming temperature, perfectly balancing the contradiction between film formation and anti-sticking in conventional acrylic resin systems. Due to the large number of carboxyl groups and good film-forming properties in the system, it can improve excellent resolubility and durability.

[0027] As some specific embodiments, the aqueous acrylic emulsion includes Wanhua Chemical's... 0836 0837 One or more of 0857.

[0028] In this invention, the aqueous polyurethane dispersion is an anionic polycarbonate polyurethane and / or acrylic modified polyurethane dispersion, with a particle size range of 50-80 nm, a minimum film-forming temperature (MFFT) of 20-70 °C, and a solid content of 30-45%. Preferably, the elongation at break is 150-450% (e.g., 200%, 250%, 300%, 350%, 400%, etc.), and the 100% modulus is 6-12 MPa. The polyurethane dispersion meeting these conditions has a small particle size and narrow particle size distribution, exhibiting characteristics of being hard and tough. It has good compatibility with acrylic emulsions, and its rheological curve is approximately that of a Newtonian fluid. In particular, it has low viscosity under low shear and minimal viscosity decrease under high shear, which helps to improve the transferability of the coating liquid during the coating process, increases the coating amount on the substrate, and thus improves the coating quality and durability.

[0029] As some specific embodiments, the aqueous polyurethane dispersion comprises Wanhua Chemical's... 3920 0301A One or more of 6112.

[0030] In this invention, the wax emulsion is one or more of nonionic polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, and carnauba wax, preferably one or more of polyethylene wax and polypropylene wax, and most preferably one or more of BASF's WAX 26, WAX35, Onkel E801, and E340.

[0031] In this invention, the defoamer is one or more of Tego825 and Tego 1488.

[0032] In this invention, the wetting agent is one or more of Tego KL245 and Hydropalat WE 3650.

[0033] In this invention, the film-forming aid is one or more of diethylene glycol methyl ether (DPM) and ethylene glycol methyl ether (PM).

[0034] In this invention, the fast-drying solvent is one or more of ethanol, isopropanol, and isobutanol.

[0035] In another aspect, the present invention provides a method for preparing the aforementioned water-based vacuum metallizing coating liquid for paper printing, comprising the following steps: according to a proportion

[0036] (1) Mix deionized water, wax emulsion, film-forming aid and fast-drying solvent at a speed of 500-800 r / min. After premixing, add waterborne acrylic emulsion and waterborne polyurethane dispersion and stir at a speed of 500-800 r / min for 30-45 min.

[0037] (2) Add the defoamer and wetting agent to the mixture in step (1) above, and stir at 800-1000 r / min for 30-45 min to obtain a vacuum aluminum water-based coating liquid for paper printing.

[0038] The coating liquid prepared by this invention has a Zein-3 cup viscosity of 13-18 s;

[0039] In this invention, the coating liquid is coated at high linear speed using a gravure printing machine, with a dry film coating amount of 2-4 gsm. After baking at 80-120℃ for 10 seconds, vacuum aluminum plating is performed, with an aluminum plating thickness of 30-50 nm. The final performance is then tested.

[0040] The vacuum metallizing aqueous coating liquid for paper printing of the present invention can produce final products with high gloss, excellent metallization effect, wear resistance, anti-blocking, chemical resistance, resolubility, printability (bubbling, knife lines, etc.), and environmental friendliness. It is suitable for various printing and coating methods, and is especially suitable for the tobacco and alcohol printing industries with extremely strict requirements for printing speed, drying speed, wear resistance, anti-blocking, and metallization appearance.

[0041] This invention provides a water-based vacuum metallizing coating liquid for paper printing, which has the following characteristics:

[0042] Beneficial effects:

[0043] (1) The coating liquid of the present invention mainly uses water as the dispersion medium and has a very low solvent content. Compared with solvent-based coating liquids, the solvent content is reduced by more than 90%. It does not contain benzene-based solvents, formaldehyde, heavy metals, halogenated hydrocarbons, or alkylphenol polyoxyethylene ether (APEO), making it safe and environmentally friendly. It can not only reduce the environmental emission tax and fee expenditures of enterprises, but also greatly reduce the impact on the environment and the harm to the human body, truly realizing the green, safe and environmentally friendly development concept.

[0044] (2) Using a specially selected alkali-soluble acrylate solid resin as a reactive macromolecular rheology-controlled emulsifier, a core-shell structured styrene-acrylic emulsion is synthesized by seed emulsion polymerization. The polymerization reaction has better stability, and the emulsion rheology is close to that of a Newtonian fluid. After the coating liquid is applied, it can quickly flow and wet the substrate to fill all the fibers of the paper. The resin has a large number of carboxyl groups that can combine with the paper fibers to form hydrogen bonds. In addition, the emulsion has a narrow particle size distribution and small particle size. The two work together to achieve the same direct coating effect as direct-coated supercalendered paper (high gloss and good transparency). Because the emulsion has a core-shell structure and a high content of carboxyl groups, it can perfectly balance the contradiction between film formation and anti-sticking in the conventional acrylic resin system.

[0045] (3) The selected polyurethane dispersion has small particle size and narrow particle size distribution, and has the characteristics of being hard and tough. It has good compatibility with acrylic emulsion and its rheological curve is similar to that of a Newtonian fluid. In particular, it has low viscosity under low shear and no significant viscosity decrease under high shear. This helps to improve the transferability of the coating liquid during the coating process, increase the coating amount on the substrate, and further improve the coating quality and performance while ensuring the requirements of anti-blocking, gloss and other properties.

[0046] (4) The coating liquid obtained by using the structural design and specific combination of low Tg / high hardness waterborne acrylic emulsion and polyurethane dispersion has high gloss and high transparency, good aluminum plating effect, wear resistance, anti-blocking, chemical resistance, resolubility, printability (foaming, knife lines, etc.), heat resistance, and environmental protection, and achieves the same direct plating effect as direct plating supercalendered paper (high gloss and good transparency). Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention. All other embodiments obtained based on the overall concept of the embodiments of the present invention without inventive step are within the protection scope of the present invention.

[0048] Gloss: The gloss of the aluminum coating is measured by placing a five-angle gloss meter on the surface of the aluminum coating film. The gloss is ≥680°.

[0049] Gloss index Fi: The whiteness of the paint film is tested at various angles using a five-angle gloss meter placed on the paint film surface. Fi = [2.69(L15-L110)]. 1.11 / (L45) 0.85 The larger Fi is, the better.

[0050] Water resistance: Wipe the paint film with a cotton swab dipped in deionized water and observe the number of times the paint film is damaged. ≥15 times.

[0051] Alcohol resistance: Wipe the paint film with a cotton swab dipped in 80% ethanol and observe the number of times the paint film is damaged. ≥5 times.

[0052] Abrasion resistance: Place the dried primer on an abrasion tester and test it 50 times at 4 psi and 85 rpm. Observe the wear of the paint film and rate it from 1 to 5 according to the degree of wear (5 is the best and 1 is the worst).

[0053] Anti-blocking: Place the paint film in an oven at 50℃ and 80% humidity, 10kg / cm² 2 Press down for 24 hours and observe the adhesion between coatings and substrates. Rate the degree of damage from 1 to 5 (5 is the best and 1 is the worst).

[0054] Anti-gloss: Place the paint film in an oven at 50℃ and 80% humidity, 10kg / cm² 2 Press down for 24h / 48h and observe the adhesion and gloss changes of "coating-coating, coating-substrate". Rate and score from 1 to 5 according to the degree of damage and change (5 is the best and 1 is the worst).

[0055] Redissolving property: Place a drop of the same coating solution on the dry film. Start timing for 5 seconds and then wipe off the ink drop with a dry paper towel. If any dried ink is not completely removed, extend the contact time between the paper towel and the dry film in increments of 5 seconds until the ink is completely removed. Record the time taken in seconds.

[0056] Alcohol emulsion test: Prepare 80% ethanol and mix it with emulsion at a ratio of ethanol:emulsion = 0.2 to 1:1. Observe whether the mixed emulsion breaks down, produces residue, cokes, or its fineness increases.

[0057] Heat resistance: Tested using a heat sealer with a pressure of 300 kPa, a test temperature of 130–180°C, and a pressing time of 1 second. Observe the surface for embossing and gloss changes when the set temperature is changed. ≥150°C.

[0058] Folding endurance: Fold the paper 180° with a folding machine and then restore it to its original shape. Check if the paint film shows any cracks, damage or breakage. If there are no problems with the appearance, it is considered as 1 time, ≥3 times.

[0059] Printability: Apply the primer mixture on a paper coating machine at a speed of 200-800 m / min and check the substrate surface for defects such as pinholes, exposed coating, and knife lines.

[0060] Foaming and foam stability: Place the coating liquid in a shaker and shake continuously for more than 3 hours. Then take it out and observe the foaming level of the emulsion in a graduated cylinder. Observe the defoaming strength of the ink every 0.5 hours. Rate and score from 1 to 5 according to the foaming and defoaming level (5 is the best and 1 is the worst).

[0061] Skin formation: After weighing the same amount of emulsion, open the container and place it in a constant temperature and humidity room. After 24 hours, test the emulsion mass reduction rate and the emulsion surface skin formation rate.

[0062] Relevant raw material information:

[0063] 0836: Core Tg = 17℃, shell Tg = 120℃, core-shell ratio between 50 / 50 and 70 / 30, particle size 68±5nm, acid value 67mgKOH / g, solid content 40%;

[0064] 0837: Core Tg = -17℃, shell Tg = 110℃, core-shell ratio 50 / 50~70 / 30, acid value 55mgKOH / g, particle size 75nm, solid content 44%;

[0065] 0857: Core Tg = -15℃, Shell Tg = 100℃, Core-shell ratio 50 / 50~70 / 30, Particle size 55±3nm, Acid value 25mgKOH / g, Solid content 42%.

[0066] 3920: Particle size 65nm, solid content: 33%, elongation at break: 400%, 100% modulus: 6.5MPa, MFFT: 23℃

[0067] 0301A: Particle size: 78nm, Solid content: 40%, Elongation at break: 160-190%, 100% modulus: 7-9MPa, MFFT: 65℃

[0068] 6112: Particle size 55nm, solid content: 31%, elongation at break: 165%, 100% modulus: 11MPa, MFFT: 35℃.

[0069] Examples 1-5

[0070] The weight proportions of the raw materials in Examples 1-5 are shown in Table 1 below, and the specific components are shown in Table 2 below:

[0071] Table 1

[0072]

[0073] Table 2

[0074]

[0075]

[0076] According to the formulations provided in Examples 1-5, the preparation method of the coating liquid in this example includes the following steps:

[0077] (1) Stir deionized water, wax emulsion, film-forming aid and fast-drying solvent at a speed of 500-800 r / min for 30 min. After premixing, add waterborne acrylic emulsion and waterborne polyurethane dispersion and stir at a speed of 500-800 r / min for 30 min.

[0078] (2) Add the defoamer and wetting agent to the mixture in step (1) above, and stir at 800-1000 r / min for 30 min to obtain the coating liquid;

[0079] (3) The coating liquid is coated at high linear speed by gravure printing machine. The dry film coating amount is 2-4 gsm. After baking at 100℃ for 10s, vacuum aluminum plating is performed. The aluminum plating thickness is 20-30 nm. The final performance is then tested.

[0080] Comparative Example 1

[0081] Do not use water-based acrylic emulsion 0836, the rest are the same as in Example 1.

[0082] Comparative Example 2

[0083] Do not use waterborne polyurethane dispersions 6112, the rest are the same as in Example 2.

[0084] Comparative Example 3

[0085] The aqueous acrylic emulsion from Example 4 was used with BASF's... PDX-7339 (Sc=43%, AC=76, MFFT=22℃) equivalent replacement 0837, the rest remain unchanged.

[0086] Comparative Example 4

[0087] The aqueous polyurethane dispersion in Example 2 was used with Covestro. Equivalent replacement of R3986 (Sc=31%, 100% modulus=10.5-12MPa, elongation at break 150-170%, minimum film-forming temperature MFFT=6℃) 6112, the rest remain unchanged.

[0088] The performance of the coating liquid in each example / comparative example was tested, and the results are shown in Table 3.

[0089] Table 3 Performance Test Results of Vacuum Metallizing Aqueous Coating Solution for Paper Printing

[0090]

[0091] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coating liquid, characterized by, It comprises the following raw materials by weight percentage: The water-based acrylic emulsion is a water-based acrylic emulsion with core-shell structure, with an acid value of 20-70 mgKOH / g, a solid content of 40-50 wt%, a core / shell ratio of 50 / 50-70 / 30, a particle size range of 50-80 nm, an inner core glass transition temperature Tg of-30-20℃, and an outer shell glass transition temperature Tg of 85-120℃; the water-based acrylic emulsion is a core-shell structure styrene-acrylic emulsion synthesized by seed emulsion polymerization using a specifically selected alkali-soluble acrylic ester solid resin as a reactive macromolecular rheological control emulsifier; wherein the specifically selected alkali-soluble acrylic ester solid resin is a styrene-acrylic resin and / or a maleic anhydride modified styrene-acrylic resin with an acid value of 200-300 mgKOH / g, a molecular weight Mw of 7500-16000 g / mol, a molecular weight distribution PDI of 1.4-2.0, and a glass transition temperature Tg of 80-120℃; The water-based polyurethane dispersion is an anionic polycarbonate polyurethane and / or acrylic modified polyurethane dispersion with a solid content of 30-45%, a minimum film formation temperature MFFT of 20-70℃, a particle size range of 50-80 nm, an elongation at break of 150-450%, and a 100% modulus of 6-12 MPa.

2. The coating liquid according to claim 1, wherein It comprises the following raw materials by weight percentage:

3. The coating liquid according to claim 1 or 2, wherein The wax emulsion is one or more of non-ionic polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, and carnauba wax.

4. The coating liquid according to claim 3, wherein The wax emulsion is one or more of polyethylene wax and polypropylene wax.

5. The coating liquid according to claim 3, wherein The wax emulsion is one or more of BASF's WAX 26, WAX 35, Onguard E801, and E340.

6. The coating liquid according to claim 1 or 2, wherein The defoaming agent is one or more of Tego 825 and Tego 1488, and / or The wetting agent is one or more of Tego KL245 and Hydropalat WE 3650, and / or The film-forming aid is one or more of diethylene glycol methyl ether DPM and ethylene glycol methyl ether PM, and / or The quick-drying solvent is one or more of ethanol, isopropyl alcohol, and isobutyl alcohol.

7. A method for preparing the coating liquid according to any one of claims 1-6, comprising the following steps: (1) stirring and mixing deionized water, a wax emulsion, a film-forming aid, and a quick-drying solvent, adding a water-based acrylic emulsion and a water-based polyurethane dispersion after premixing, and stirring; (2) adding a defoaming agent and a wetting agent to the mixture in step (1) and stirring to obtain the coating liquid.

8. Use of the coating liquid according to any one of claims 1-6 in the printing industry.

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