Environment-friendly water-based ink, tipping paper and preparation method of environment-friendly water-based ink

Abstract

The invention relates to the field of water-based ink and tipping paper, in particular to environment-friendly water-based ink, tipping paper and a preparation method of the environment-friendly water-based ink. The environment-friendly water-based ink is prepared from the following raw materials in parts by weight: 25 to 35 parts of EVA (Ethylene-Vinyl Acetate) emulsion, 3 to 5 parts of polyvinylpyrrolidone, 4 to 6 parts of nano reinforcing agent, 0.3 to 1 part of aluminum citrate, 0.1 to 1 part of antibacterial agent, 2 to 8 parts of pigment, 0.05 to 0.2 part of defoaming agent, 0.2 to 1 part of flatting agent, 0.2 to 0.8 part of emulsifying agent, 0.05 to 0.15 part of organic acid and 60 to 80 parts of water. The prepared printing ink is excellent in performance, has good environment-friendly, antibacterial, safe and quick-drying performance, is suitable for preparing tipping paper for cigarettes, and is high in stability, and a film forming matter of the printing ink is high in wear resistance and adhesive force effect.

Description

Technical Field

[0001] This invention relates to the field of water-based inks and tipping paper, specifically to an environmentally friendly water-based ink, tipping paper, and a method for preparing the same. Background Technology

[0002] The cigarette ink used in cigarette tipping paper is a highly specialized industrial ink that needs to meet requirements for safety, environmental protection, ease of printing, and physical properties.

[0003] Inks used for tipping paper are classified into solvent-based inks, alcohol-based inks, and water-based inks.

[0004] Solvent-based inks use traditional organic solvents such as toluene and ethyl acetate. Although they are widely used due to their excellent printability, fast drying and cost advantages, they pose significant risks of solvent residue and VOC emissions, which are unfriendly to the health of production personnel and the environment.

[0005] Alcohol-soluble inks achieve a good balance between environmental protection and performance. They use alcohols such as ethanol as the main solvent. Although they still contain organic components, they are more environmentally friendly than traditional solvent-based inks, with significantly reduced VOC content and toxicity. The advantages of this type of ink are that it can improve the gloss, adhesion and water resistance of printed materials, and has excellent printability. It is often used for printing cigarette packs or tipping paper with special requirements for gloss and abrasion resistance, and is an important choice in the transition from traditional inks to water-based inks.

[0006] Water-based inks represent the core development direction for tobacco inks today. Using water as the main solvent, their biggest advantages are environmental friendliness and safety. These inks are non-toxic and odorless, and the production process is non-flammable and non-explosive, essentially eliminating the risks of organic solvent emissions and residues.

[0007] Although water-based inks are characterized by high safety performance, optimizing their drying rate, film-forming properties, and antibacterial properties remains a technical challenge that needs to be addressed. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides an environmentally friendly water-based ink, tipping paper, and a method for preparing the same.

[0009] In one embodiment of the present invention, an environmentally friendly water-based ink is provided, comprising, by weight, 25-35 parts EVA emulsion, 3-5 parts polyvinylpyrrolidone, 4-6 parts nano-reinforcing agent, 0.3-1 part aluminum citrate, 0.1-1 part antibacterial agent, 2-8 parts pigment, 0.05-0.2 parts defoamer, 0.2-1 part leveling agent, 0.2-0.8 parts emulsifier, 0.05-0.15 parts organic acid, and 60-80 parts water.

[0010] In another embodiment of the present invention, the nano-reinforcing agent is selected to include nanoscale fumed silica.

[0011] In another embodiment of the present invention, the antibacterial agent is selected as an extract obtained by extraction of cinnamon, neem, and hazelnut in a weight ratio of 1:(2-3):(2-3), followed by microencapsulation. The extraction process includes immersion in an aqueous ethanol solution, followed by filtration, concentration, ethyl acetate extraction, and concentration to remove the ethyl acetate. Microencapsulation uses gelatin and gum arabic as wall materials and is cross-linked and cured using genipin. The synergistic combination of neem and hazelnut optimizes the antibacterial effect, and the further use of cinnamon results in an antibacterial agent with excellent performance.

[0012] In another embodiment of the present invention, the organic acid is selected as at least one of lactic acid and citric acid.

[0013] In another embodiment of the present invention, the pigment selected includes at least one of phthalocyanine blue, phthalocyanine green, and permanent yellow.

[0014] In another embodiment of the invention, the emulsifier selected includes fatty alcohol polyoxyethylene ether.

[0015] In another embodiment of the present invention, the defoamer selected includes at least one of BYK-1640, BYK-021, Dow Corning DC-62, and Dow Corning DC-65.

[0016] In another embodiment of the present invention, the leveling agent selected includes at least one of Dow Corning DC-51, BYK-333, and BYK-381.

[0017] In this invention, EVA emulsion, as the main film-forming substance, does not contain volatile organic solvents (VOCs) and replaces traditional solvent-based resins, thus providing high safety. In addition, the polar groups of vinyl acetate provide excellent adhesion, and the ethylene segments impart flexibility and tear resistance, adapting to the high-speed packaging requirements of tipping paper. After the moisture evaporates, the latex particles fuse together to form a continuous and dense polymer film.

[0018] In this invention, the hydrophilic pyrrolidone ring and the hydrophobic alkyl chain in the polyvinylpyrrolidone molecule form an amphiphilic structure, which prevents pigment agglomeration through steric hindrance. It has good biocompatibility, biodegradable fragments, and adsorbs onto the pigment surface to form a protective layer, inhibiting sedimentation and flocculation.

[0019] In this invention, the lipophilic aliphatic long chains of the fatty alcohol polyoxyethylene ether emulsifier can anchor on the surface of EVA emulsion particles, pigment aggregates, and nano-vaporized silica, while the hydrophilic polyoxyethylene chains fully extend into the aqueous phase, forming a denser and thicker polymeric hydration layer. This provides steric stabilization for the ink system, synergistically working with the steric stabilization mechanism of the original polyvinylpyrrolidone (PVP). This more effectively prevents the aggregation, flocculation, or demulsification of solid particles and emulsion particles due to Brownian motion collisions during storage, shearing, or heating. Especially when facing changes in water quality or temperature fluctuations, it significantly improves the system's tolerance. This emulsifier effectively reduces the surface tension of the system, allowing for faster and more uniform wetting and coating of pigments and nanofillers during ink preparation, improving dispersion efficiency. During coating and printing, it promotes better ink spreading on the surface of the tipping paper substrate, reducing defects such as pinholes and fisheyes caused by uneven surface tension.

[0020] In this invention, nanoparticles of nano-sized fumed silica form physical cross-linking points in the EVA film, improving the coating's hardness, wear resistance, and scratch resistance. Its porous structure generates a capillary effect, accelerating the migration of moisture to the surface. Furthermore, the three-dimensional network formed by hydrogen bonds facilitated by silica imparts suitable thixotropic properties to the ink, causing it to thin during printing and recover its high viscosity after standing to prevent sagging.

[0021] In this invention, aluminum citrate replaces formaldehyde-based crosslinking agents, resulting in no release of toxic substances. 3+ It forms coordination bonds with the carboxyl groups in EVA and the carbonyl groups in PVP. In addition, the citrate polycarboxyl groups form hydrogen bond networks with polymers and pigments. The cross-linked network accelerates the solidification of the system and reduces drying time.

[0022] In this invention, plant-derived antibacterial agents are selected, which are green and environmentally friendly and have excellent antibacterial effects. They can effectively inhibit the growth of ink bacteria and prevent the tipping paper from being contaminated by bacteria.

[0023] In this invention, water is chosen as an environmentally friendly carrier, completely replacing organic solvents, which has both safety and environmental benefits.

[0024] In this invention, organic acids are selected to control the pH of the ink system, protect the stability of the ink, optimize the crosslinking efficiency of aluminum citrate, and inhibit pigment hydrolysis and aggregation.

[0025] In another embodiment of the present invention, a method for preparing an environmentally friendly water-based ink is provided, comprising the following steps: (1) In the mixing tank, add water that is 30-45% of the total amount of water, turn on the stirring, add polyvinylpyrrolidone, emulsifier and aluminum citrate, stir and mix to obtain mixture one; (2) Add pigment and nano-reinforcing agent to mixture one, stir and mix to obtain slurry; add EVA emulsion, stir and obtain mixture two; (3) Add antibacterial agent and leveling agent to mixture 2, stir and mix, then add defoamer, organic acid dissolved in water beforehand and remaining water, stir and mix, filter and fill to obtain environmentally friendly water-based ink.

[0026] In another embodiment of the present invention, a tipping paper is provided, the surface of which is coated with the above-mentioned environmentally friendly water-based ink.

[0027] In another embodiment of the present invention, a method for preparing tipping paper is provided, comprising the following steps: providing tipping paper; coating the surface of the tipping paper with the environmentally friendly water-based ink; drying and cooling; slitting and rolling.

[0028] Beneficial effects of this invention: This invention uses water as the continuous phase to fundamentally eliminate VOC emissions from solvent-based inks. It selects EVA emulsion as the main film-forming substance to improve ink safety. The invention utilizes a flexible EVA matrix and rigid nano-silica particles to form a soft / hard structure. The polymer continuous phase provides toughness and excellent adhesion, while the nanoparticles provide excellent strength and abrasion resistance. Furthermore, aluminum citrate ions crosslink to form a three-dimensional network, enhancing tensile strength, flexural strength, and abrasion resistance. In this invention, high specific surface area nano-SiO2 generates a capillary effect, and the aluminum citrate crosslinking reaction occurs simultaneously with water evaporation, shortening surface drying and hard drying times. A leveling agent forms a uniform thin layer, increasing the evaporation area. The combination of physical evaporation and chemical crosslinking curing achieves rapid drying.

[0029] The antibacterial agent selected in this invention uses plant extracts as active ingredients, which are green and safe. It optimizes the types of active ingredients by selecting neem and rabbit's ear grass in synergy to enhance the antibacterial effect and achieve a synergistic antibacterial effect. Furthermore, cinnamon is used as an active ingredient in the antibacterial agent to further enhance its antibacterial ability. Moreover, to ensure the stability of the antibacterial agent in inks, this invention microencapsulates the extract to obtain the antibacterial agent, achieving effective and sustained antibacterial performance. Detailed Implementation

[0030] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0031] Example 1: Preparation and testing of antibacterial active ingredient - extract Extract 1: Take 1 part by weight of cinnamon leaves, 2.5 parts of neem leaves and 2.5 parts of rabbit ear grass, crush them together as raw materials, add 20 times the weight of the raw materials in 65wt% ethanol solution, stir and extract at 50℃ and 120rpm for 2 hours, filter and concentrate to 1.15 times the weight of the raw materials to obtain a concentrate, add 5 times the weight of the concentrate in ethyl acetate, stir and extract at 35℃ and 120rpm for 2 hours, let stand for 0.5 hours to separate the layers, take the upper layer material and concentrate to remove ethyl acetate to obtain the extract.

[0032] Extract 2: The difference from Extract 1 is that 1 part of cinnamon leaves and 5 parts of rabbit ear grass are crushed together as raw materials, otherwise the same.

[0033] Extract 3: The difference from Extract 1 is that 1 part cinnamon leaves and 5 parts neem leaves are crushed together as raw materials, otherwise the same.

[0034] Extract 4: The difference from Extract 1 is that 1 part cinnamon leaves, 1 part neem leaves and 4 parts rabbit ear grass are crushed together as raw materials, and the rest are the same.

[0035] Extract 5: The difference from Extract 1 is that 1 part cinnamon leaves, 4 parts neem leaves and 1 part rabbit ear grass are crushed together as raw materials, and the rest are the same.

[0036] The antibacterial properties of the extract were tested to select the optimal combination for preparing an antibacterial agent. The specific testing steps are as follows: Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8739 were used as test bacteria. 0.75 mL of the test bacterial culture (bacterial concentration of 5 × 10⁻⁶) was taken. 6 The sample solution (cfu / mL) was evenly spread on a sterile petri dish. Then, 0.15 mL of the sample solution (composed of 2.5 wt% Tween-80 aqueous solution and extract at a weight ratio of 100:1) was dropped onto the surface of sterile 9 mm diameter filter paper. The filter paper was then placed in the petri dish (in the center of the spread solution). The dish was incubated at 37 °C with 5% CO2 for 24 h. The diameter of the inhibition zone was measured. The experiment was repeated three times. The results are shown in Table 1.

[0037] Table 1: Diameter of the inhibition zone

[0038] Based on the test results in Table 1, it can be seen that extract 1 has the best antibacterial performance. The comparison between extracts 2-3 and 1 can verify that the simultaneous use of neem leaf and rabbit ear grass can synergistically enhance the antibacterial performance. When preparing the extracts, the selection of cinnamon, neem and rabbit ear grass in a weight ratio of 1:(2-3):(2-3) results in the best antibacterial performance.

[0039] Example 2 Preparation of antibacterial agent The above-mentioned extract 1 was used as the raw material for the antibacterial agent. The specific preparation method was as follows: the above-mentioned extract 1 was prepared, and an aqueous solution containing 1 wt% gelatin and 1 wt% gum arabic was prepared. The pH of the aqueous solution was adjusted to 4.3 with acetic acid. Extract 1 was added at a ratio of 1:1.3 of the weight of the extract to the total weight of gelatin and gum arabic. The homogenate was homogenized at 8000 rpm for 15 minutes to obtain a homogenate. The temperature of the homogenate was maintained at 45℃ and water with a weight of 3 times that of the homogenate was slowly added. The pH was adjusted to 4.5 again with acetic acid. The homogenate was initially microencapsulated by stirring at 300 rpm for 30 minutes at 45℃. Then the temperature was lowered to 30℃ and kept warm. Genipin (CAS: 6902-77-8, added as 5 wt% genipin aqueous dispersion) with a weight of 10% of the gelatin was added. The reaction was stirred at 200 rpm for 10 hours. The mixture was then refrigerated at 4℃ for 3 hours. After filtration, the filter residue was washed with deionized water to obtain the antibacterial agent.

[0040] Example 3 Preparation of Ink Ink raw material information: EVA emulsion: Dalian Chemical Co., Ltd., Taiwan, model DA-102, solid content 55%, Tg=0℃; Polyvinylpyrrolidone: K30; Nano-reinforcing agent: Nano-grade fumed silica, Degussa hydrophilic fumed silica AEROSIL200; Pigment: Phthalocyanine Blue, BASF Dispers Blue 70-0507; Defoamer: BYK-1640; Leveling agent: BYK-381; Emulsifier: AEO-9; Organic acid: Lactic acid.

[0041] Prepare materials according to the dosage in Table 2, and measure the dosage by weight.

[0042] Table 2: Raw Material Composition

[0043] Ink 6: Based on Ink 1, the nano-reinforcing agent is replaced with an equal weight of nano-calcium carbonate (WN503).

[0044] The preparation method of the above ink is as follows: (1) In the mixing tank, add water equal to 40% of the total amount of water, turn on the stirring at 400 rpm, slowly add polyvinylpyrrolidone, emulsifier and aluminum citrate, stir for 20 minutes to mix, and obtain mixture one; (2) Add pigment and nano-reinforcing agent to mixture one, stir at 1000 rpm for 35 minutes to obtain slurry; add EVA emulsion, continue stirring at 450 rpm for 15 minutes to obtain mixture two; (3) Add antibacterial agent and leveling agent to mixture 2, stir and mix at 400 rpm for 20 minutes, then add defoamer, organic acid dissolved in water beforehand (organic acid and water are prepared in a weight ratio of 1:12) and remaining water, stir and mix at 400 rpm for 20 minutes, filter and fill to obtain environmentally friendly water-based ink.

[0045] Example 4: Ink Testing Drying time test: The surface drying time (method A) and actual drying time (method B) are tested according to the method of GB / T 1728-2020.

[0046] Thermal storage stability: The ink sample was sealed and stored in a constant temperature oven at 50±2°C for 7 days; after being taken out and allowed to return to room temperature, the viscosity change rate was measured.

[0047] Abrasion resistance: The abrasion resistance As (%) was tested according to section 6.8 - ink layer abrasion resistance as described in GB / T 7706-2008.

[0048] Adhesion: Adhesion A (%) was tested according to Chapter 4 - Disc Peel Method as described in GB / T 13217.7-2023.

[0049] The test results are shown in Table 3.

[0050] Table 3: Ink Performance Test Results

[0051] According to the test results in the table, the ink prepared by this invention has a short drying time, high stability, and excellent mechanical properties, exhibiting good overall performance.

[0052] Compared to Ink 1, Ink 3 lacks nano-fumed silica, resulting in longer drying time, higher abrasion resistance, and better adhesion. The porous structure of nano-fumed silica (AEROSIL 200) can form a capillary network within the ink film, accelerating the migration of moisture to the surface. Furthermore, as rigid nanoparticles, it is uniformly dispersed in the EVA ink film, acting as a "physical cross-linking point" and reinforcing agent, significantly improving the hardness and scratch resistance (peeling) of the ink film, and enhancing abrasion resistance and adhesion.

[0053] Ink 4 lacks aluminum citrate; compared to Ink 1, its drying time is longer, and its abrasion resistance and adhesion are reduced. The Al in aluminum citrate... 3+It coordinates and crosslinks with the polar groups of EVA and PVP, while citric acid itself forms a hydrogen bond network. This "chemical crosslinking" process occurs simultaneously with the "physical evaporation" of water, accelerating the system's curing and film formation. Relying solely on water evaporation, lacking this crosslinking effect, would prolong the drying time. Furthermore, the crosslinked network significantly enhances the cohesive strength and resistance to plastic deformation of the ink film, strengthening its cohesive force and making damage less likely to occur within the coating. Moreover, Al... 3+ Citrate and citric acid can form coordination bonds and hydrogen bonds with the surface of paper fibers, enhancing interfacial chemical bonding and improving mechanical properties.

[0054] Ink 5 does not use polyvinylpyrrolidone (PVP), so the drying rate is less affected, but the stability, abrasion resistance and hardness of the ink are significantly affected. PVP is adsorbed on the surface of pigments and nanoparticles through its amphiphilic structure, forming a steric hindrance protective layer to prevent nanoparticles or pigments from aggregating due to van der Waals forces, which would affect the ink's storage stability, film uniformity and film stress uniformity.

[0055] In ink 6, nano-calcium carbonate is used instead of fumed SiO2. Since nano-calcium carbonate is a common spherical filler particle, it mainly plays an incremental and slightly reinforcing role. It does not have the porous structure (no capillary effect), high specific surface area and strong polarity (difficult to form a strong hydrogen bond thixotropic network) of fumed SiO2, nor the better nano-reinforcing efficiency. Therefore, its contribution to "drying", "stabilization" and "enhancing mechanical properties" is weaker than that of fumed SiO2, resulting in performance indicators that are slightly lower than those of ink 1.

[0056] Example 5 Tipping paper A is prepared as follows: providing tipping paper; coating the surface of the tipping paper with the environmentally friendly water-based ink 1; drying and cooling; slitting and rolling.

[0057] Tipping paper B is prepared as follows: providing tipping paper; coating the surface of the tipping paper with the environmentally friendly water-based ink 2; drying and cooling; slitting and rolling.

[0058] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An environmentally friendly water-based ink, characterized by, The raw material composition comprises, by weight: 25-35 parts of EVA emulsion, 3-5 parts of polyvinylpyrrolidone, 4-6 parts of nano-enhancing agent, 0.3-1 part of aluminum citrate, 0.1-1 part of antibacterial agent, 2-8 parts of pigment, 0.05-0.2 part of defoaming agent, 0.2-1 part of leveling agent, 0.2-0.8 part of emulsifier, 0.05-0.15 part of organic acid, and 60-80 parts of water.

2. The environmentally friendly water-based ink according to claim 1, characterized in that, The nano-enhancing agent comprises nanoscale fumed silica.

3. The environmentally friendly water-based ink according to claim 1, characterized in that, The antibacterial agent is an extract of cinnamomum cassia, khaya senegal, and ranunculus japonicus, and the extract is microencapsulated.

4. The environmentally friendly water-based ink according to claim 1, characterized in that, The organic acid is at least one of lactic acid and citric acid.

5. The environmentally friendly water-based ink according to claim 1, characterized in that, The pigment comprises at least one of phthalocyanine blue, phthalocyanine green, and permanent yellow; and the emulsifier comprises fatty alcohol polyoxyethylene ether.

6. The environmentally friendly water-based ink according to claim 1, characterized in that, The defoaming agent comprises at least one of BYK-1640, BYK-021, DC-62, and DC-65.

7. The environmentally friendly water-based ink according to claim 1, characterized in that, The leveling agent comprises at least one of DC-51, BYK-333, and BYK-381.

8. A method for preparing the eco-friendly water-based ink according to any one of claims 1 to 7, characterized by, The method comprises the following steps: (1) adding water in an amount of 30-45% of the total water in a batching tank, and stirring, adding polyvinylpyrrolidone, emulsifier, and aluminum citrate, and stirring and mixing to obtain a mixture one; (2) adding pigment and nano-enhancing agent to the mixture one, stirring and mixing, adding EVA emulsion, and stirring to obtain a mixture two; (3) adding antibacterial agent and leveling agent to the mixture two, stirring and mixing, then adding defoaming agent, organic acid dissolved in water in advance, and the remaining water, stirring and mixing, filtering, and filling to obtain the environmentally-friendly water-based ink.

9. A tipping paper, characterized by The tipping paper is coated with the environmentally-friendly water-based ink according to any one of claims 1-7.

10. A method of manufacturing a tipping paper according to claim 9, characterized in that, The method comprises the following steps: providing waterproof paper; coating the surface of the waterproof paper with the environmentally-friendly water-based ink; drying and cooling; slitting and winding. The method comprises the following steps: providing waterproof paper; coating the surface of the waterproof paper with the environmentally-friendly water-based ink; drying and cooling; slitting and winding.

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