A packaging adhesive for a high-speed cigarette packaging machine and its preparation method

Abstract

This invention relates to the field of tobacco adhesives, specifically to a packaging adhesive for a high-speed tobacco packaging machine and its preparation method. The packaging adhesive, by weight percentage, comprises 40-60% vinyl acetate-ethylene copolymer emulsion, 10-20% polyvinyl alcohol solution, 5-12% bio-based modifier, 0.03-0.1% plasticizer, 5-10% tackifying resin, 0.5-2% emulsifier, 0.1-0.5% initiator, 0.1-0.5% wetting agent, 0.1-0.5% defoamer, 0.5-1% preservative, and 30-40% deionized water. By employing a bio-based modifier, a three-dimensional network structure is constructed, and hydrophobic groups are introduced to improve the water resistance, temperature resistance, and cohesive strength of the packaging adhesive, while simultaneously reducing VOCs release. The tackifying resin and plasticizer, through the synergistic effect of molecular chain plasticization and interfacial tackification, lower the glass transition temperature of the system and improve initial tack and the flexibility of the packaging adhesive.

Description

Technical Field

[0001] This invention relates to the field of tobacco adhesives, and more specifically, to a packaging adhesive for a high-speed tobacco packaging machine and its preparation method. Background Technology

[0002] The GDH1000 cigarette packaging machine is an internationally advanced high-speed hard-pack packaging equipment introduced from the Italian company GD. It is currently widely used by major domestic cigarette manufacturers, with an actual production speed of up to 1000 packs per minute. It features high automation and high intelligence, with all packaging materials supplied automatically. The supply, transfer, and folding of the label paper are key processes in hard-pack packaging, directly affecting equipment efficiency and cigarette packaging quality. Cigarette packaging adhesive, as a core auxiliary material for the stable operation of the GDH1000 packaging machine, is mainly used for bonding and fixing the label paper, inner frame packaging paper, carton packaging paper, and sealing paper. Its performance directly determines the cigarette packaging qualification rate, equipment operational stability, and overall production efficiency.

[0003] The ultra-high-speed packaging adhesive on the GDH1000 packaging machine is applied using a spray-type application method. The adhesive is evenly sprayed from nozzles onto the surfaces of the cigarette boxes requiring bonding, ensuring uniform and continuous application. This method allows for quick and accurate coverage of the bonding areas, improving production efficiency. Spray-type application requires precise control of nozzle operating parameters, such as spraying speed and adhesive volume, to avoid over-application that could clog the nozzles or result in uneven application. This adhesive delivery method requires the packaging adhesive to have a low viscosity and moderate solids content. If the viscosity is too high, a large amount of adhesive will be applied, potentially affecting the adhesive's drying speed. If the solids content is too high, scale and deposits may form at the nozzles during machine downtime, clogging the adhesive delivery and increasing cleaning costs and maintenance time. If the solids content is too low, the adhesive's drying speed will be reduced, resulting in poor film-forming properties and potentially causing burrs and weak adhesion on the cigarette boxes.

[0004] As a high-speed automated rigid box packaging machine, the GDH1000's high-speed, high-precision, and intelligent operation places extremely high demands on the compatibility, adhesion performance, environmental friendliness, and intelligent linkage of tobacco packaging adhesives. Considering the current application status of tobacco packaging adhesives in the industry, common problems mentioned in reference materials such as adhesion failure and poor equipment compatibility, and the specific operational requirements of the GDH1000, the tobacco packaging adhesives currently used in this equipment mainly suffer from four major shortcomings: insufficient equipment compatibility, imperfect product performance, failure to meet green and environmental protection standards, and lack of intelligent adaptation. These are detailed below:

[0005] (1) Insufficient equipment compatibility:

[0006] Most packaging adhesives are not customized for the high-speed characteristics of the equipment. Their rheological properties and drying speeds do not match the operational requirements of the GDH1000 high-speed cigarette packaging machine. High-speed adhesive supply is prone to leakage, and low-speed adhesive supply is prone to overflow. They have poor compatibility with multiple materials such as transfer metallized paper, resulting in high delamination rates and easy smudging of printed patterns. They have poor environmental adaptability, and temperature and humidity fluctuations and equipment vibrations can easily lead to bonding failure, increasing the frequency of downtime and adhesive replenishment.

[0007] (2) Product performance is imperfect:

[0008] Under high-speed operation of 1000 packs / minute, the existing packaging adhesive has insufficient drying speed, and defects such as opening, popping, and curling are prone to occur after bonding. Especially for packaging paper with smooth materials, the adhesive has insufficient wettability, and the bonding strength cannot meet the needs of long-term storage and transportation of cigarettes, resulting in a decrease in the packaging qualification rate.

[0009] (3) Failure to meet green and environmental protection standards:

[0010] Some products contain solvents that release VOCs, which are harmful to health and pollute the environment; the amount of adhesive applied is large and the utilization rate is low, which does not meet the requirements for volume reduction; the adhesive film cannot be naturally degraded, and the production process easily generates waste, which does not conform to the industry's green development trend.

[0011] Therefore, it is necessary to solve the core problems that exist when existing general-purpose tobacco packaging adhesives are applied to the GDH1000 high-speed tobacco packaging machine, such as poor compatibility, unstable bonding performance, insufficient environmental resistance, and imbalance between environmental protection and economy. Summary of the Invention

[0012] To address at least one of the problems mentioned in the background art, the present invention provides a packaging adhesive for a high-speed cigarette packaging machine and a method for preparing the same.

[0013] In a first aspect, the present invention provides a packaging adhesive for a high-speed cigarette packaging machine, comprising, by weight percentage:

[0014] 20-50% vinyl acetate-ethylene copolymer emulsion, 50-10% polyvinyl alcohol solution, 2-6% bio-based modifier, 0.03-0.1% plasticizer, 2-5% tackifying resin, 0.5-2% emulsifier, 0.1-0.5% initiator, 0.1-0.5% wetting agent, 0.1-0.5% defoamer, 0.5-1% preservative and 15-25% deionized water.

[0015] Optionally, the packaging adhesive of a high-speed cigarette packaging machine comprises, by weight percentage:

[0016] The mixture contains 50% vinyl acetate-ethylene copolymer emulsion, 10% polyvinyl alcohol solution, 6.4% bio-based modifier, 0.1% plasticizer, 5% tackifying resin, 2% emulsifier, 0.5% initiator, 0.5% wetting agent, 0.5% defoamer, 1% preservative and 24% deionized water.

[0017] Optionally, the packaging adhesive of a high-speed cigarette packaging machine also includes a pH adjuster; specifically, the pH adjuster is sodium bicarbonate.

[0018] Optionally, the polyvinyl alcohol solution is an aqueous solution of polyvinyl alcohol, specifically a deionized aqueous solution of polyvinyl alcohol.

[0019] In the formulation of the packaging adhesive of this invention, the main functions of each component are as follows:

[0020] The vinyl acetate-ethylene copolymer (VAE) emulsion serves as a substrate for film formation and adhesion. The vinyl acetate-ethylene copolymer emulsion of this invention is obtained by purchase.

[0021] The functions of polyvinyl alcohol (PVA) solution include thickening, emulsion stabilization, and film formation.

[0022] The role of bio-based modifiers is to increase the proportion of bio-based components, improve temperature resistance, water resistance, initial tack, and environmental performance, and reduce costs.

[0023] Plasticizers serve to lower the glass transition temperature, increase flexibility, and improve initial tack, among other things.

[0024] The function of tackifying resins is to improve initial tack and cohesive strength, etc.

[0025] The function of emulsifiers is to emulsify and disperse, control particle size, and stabilize emulsions;

[0026] The function of initiators is to suppress foam and defoam.

[0027] Preservatives are used to prevent mold and extend shelf life, etc.

[0028] The function of deionized water is to adjust the solid content and viscosity, etc.

[0029] Optionally, the vinyl acetate-ethylene copolymer emulsion has an ethylene content of 18-25% and a solids content of 50-55%.

[0030] Optionally, a method for preparing a vinyl acetate-ethylene copolymer emulsion.

[0031] Optionally, the polyvinyl alcohol solution has a degree of alcoholysis of 87-99%, a degree of polymerization of 1700-2400, and a solids content of 18-22%.

[0032] Optionally, the degree of alcoholysis of the polyvinyl alcohol solution is 90%.

[0033] Optionally, the bio-based modifier includes bio-based polyols, lignin sulfonates, or starch derivatives.

[0034] Optionally, the starch derivative includes cationic starch in etherified starch, etherified by a quaternary ammonium salt.

[0035] Optionally, the plasticizer includes dipropylene glycol dibenzoate, epoxidized soybean oil, or triacetin.

[0036] The tackifying resin includes hydrogenated rosin, rosin glycerol ester, or terpene resin;

[0037] The emulsifier includes anionic emulsifiers and nonionic emulsifiers, and the mass ratio of the anionic emulsifier to the nonionic emulsifier is 1:1.5.

[0038] The initiator includes ammonium persulfate, potassium persulfate, or sodium persulfate;

[0039] The wetting agent includes organically modified siloxanes or acetylenic diols.

[0040] The defoamer includes polyether siloxane or mineral oil-based defoamers;

[0041] The preservatives include isothiazol quinolinone preservatives.

[0042] Optionally, the alkynyl diol wetting agent includes Surfynol 104E from Evonik's Surfynol series (classic alkynyl diol parent: 2,4,7,9-tetramethyl-5-decyn-4,7-diol);

[0043] Mineral oil-based defoamers include those from BASF's Foamaster series;

[0044] Isothiazolinone preservatives include methylethiozolinone.

[0045] Optionally, the anionic emulsifier includes sodium dodecyl sulfate or sodium dodecyl sulfonate; the nonionic emulsifier includes nonylphenol polyoxyethylene ether or fatty alcohol polyoxyethylene ether.

[0046] Optionally, the polyvinyl alcohol aqueous solution is obtained by mixing polyvinyl alcohol and deionized water.

[0047] Secondly, the present invention provides a method for preparing packaging adhesive for a high-speed cigarette packaging machine, comprising the following steps:

[0048] A VAE-PVA composite emulsion system in which polyethylene solution is adsorbed onto the surface of vinyl acetate-ethylene copolymer latex particles is obtained by mixing and stirring vinyl acetate-ethylene copolymer emulsion, emulsifier, initiator solution accounting for 50% of the total initiator solution and deionized water;

[0049] The VAE-PVA composite emulsion system, bio-based modifier, and plasticizer are mixed and stirred. Then, tackifying resin, the remaining initiator, wetting agent, preservative, and defoamer are added in batches to obtain a composite adhesive. The composite adhesive is then post-treated to obtain a packaging adhesive.

[0050] Optionally, the initiator solution is obtained by mixing an initiator with deionized water, wherein the mass ratio of the initiator to deionized water is 9:1.

[0051] Optionally, the post-processing includes adjusting the solid content, viscosity, and pH value of the composite adhesive solution using deionized water and a pH adjuster, and filtering it through a 100-200 mesh filter to obtain the packaging adhesive.

[0052] The present invention has the following beneficial effects:

[0053] This method utilizes bio-based materials and VAE-PVA composite emulsion system to form intermolecular hydrogen bonds and mild covalent crosslinks, constructing a three-dimensional network structure. The introduction of hydrophobic groups enhances the water resistance, temperature resistance, and cohesiveness of the adhesive layer, giving the transfer adhesive excellent weather resistance. Under humid and hot conditions, it shows no re-adhesion or discoloration after 30 minutes, exhibits excellent water resistance, and after 24 hours of immersion, the inner adhesive film does not bubble or delaminate, with a strength retention rate of ≥92%. Detailed Implementation

[0054] The invention will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are described merely to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0055] As used in this article, the term “including” and its variations are to be interpreted as an open-ended term meaning “including but not limited to”.

[0056] Example 1

[0057] Step 1, Raw material preparation:

[0058] 510 kg of VAE (vinyl acetate-ethylene copolymer) emulsion, 120 kg of PVA (polyvinyl alcohol) aqueous solution, 280 kg of deionized water, 70 kg of bio-based modifier, 6 kg of plasticizer, 55 kg of tackifier, 12 kg of emulsifier, 4 kg of initiator, 5 kg of wetting agent, 5 kg of defoamer, 5 kg of preservative, and 5 kg of pH adjuster.

[0059] The VAE emulsion has an ethylene content of 20% and a solids content of 55%.

[0060] The degree of alcoholysis of PVA aqueous solution is 90%, the degree of polymerization is about 2000, and the solid content is 20%.

[0061] The bio-based modifier is lignin sulfonate;

[0062] The plasticizer is dipropylene glycol dibenzoate;

[0063] The tackifier is rosin glycerol ester;

[0064] The initiator is ammonium persulfate, and the initiator is prepared into an initiator solution containing 10% water using deionized water;

[0065] The emulsifier is a compound emulsifier of anionic and nonionic emulsifiers, which is composed of sodium dodecyl sulfate and nonylphenol polyoxyethylene ether in a mass ratio of 1:1.5.

[0066] The wetting agent is an organically modified siloxane;

[0067] The defoamer is a mineral oil-based defoamer;

[0068] The preservative is an isothiazolinone;

[0069] The pH adjuster is sodium bicarbonate.

[0070] Step 2, Prepare PVA aqueous solution:

[0071] Add deionized water (60% of the total deionized water) to the reactor, heat to 90℃ and start stirring (150-200 r / min). Slowly add PVA, controlling the feeding speed to be uniform and avoid clumping. Maintain the temperature at 85-90℃ and stir for 1.5-2.5 hours until the PVA is completely dissolved, forming a uniform and transparent PVA aqueous solution (20% solid content). Turn off the heating and allow it to cool naturally to room temperature (25±2℃) for later use.

[0072] Step 3, Preparation of the composite adhesive:

[0073] Add the VAE emulsion to another reactor, turn on the stirrer, control the speed at 100-150 r / min, and stir for 10-20 min;

[0074] Slowly add the PVA aqueous solution prepared in step 2 into the reaction vessel. After the addition is completed, continue to add emulsifier, initiator solution accounting for 50% of the total initiator solution, and deionized water into the reaction vessel. Keep the stirring speed constant and continue stirring for 60-70 minutes to allow PVA to be fully adsorbed on the surface of VAE latex particles and form a stable VAE-PVA composite emulsion system.

[0075] Add the bio-based modifier and plasticizer sequentially to the VAE-PVA composite emulsion system reactor, and stir for 50-70 minutes to allow the bio-based modifier to fully integrate with the VAE-PVA composite emulsion system, forming a hydrogen bond network and improving the system's water resistance and initial tack. After stirring, add the tackifying resin and the remaining initiator, and continue stirring for 40-60 minutes until the tackifying resin is completely dissolved and evenly dispersed.

[0076] Add a wetting agent to the reaction vessel and stir for 8-12 minutes to ensure uniform dispersion of the wetting agent and reduce the surface tension of the composite emulsion; then add the preservative and defoamer and stir for 10-20 minutes to ensure uniform dispersion of the preservative and defoamer, achieving defoaming and antibacterial effects, and obtain the composite emulsion.

[0077] Step 4, Post-processing:

[0078] Add deionized water and pH adjuster to the composite adhesive solution, stir for 20-30 minutes, and adjust the solid content, viscosity and pH of the composite adhesive solution to meet the preset requirements; filter with a 100-200 mesh filter to remove impurities and a small amount of undissolved particles to obtain the packaging adhesive for high-speed cigarette packaging machines, and seal and store for later use.

[0079] Example 2

[0080] Step 1, Raw material preparation:

[0081] 480 kg of VAE emulsion, 180 kg of PVA aqueous solution, 310 kg of deionized water, 60 kg of bio-based modifier, 6 kg of plasticizer, 55 kg of thickener, 12 kg of emulsifier, 4 kg of initiator, 5 kg of wetting agent, 5 kg of defoamer, 5 kg of preservative, and 5 kg of pH adjuster.

[0082] The VAE emulsion has an ethylene content of 20% and a solids content of 55%.

[0083] The degree of alcoholysis of PVA aqueous solution is 90%, the degree of polymerization is about 2000, and the solid content is 20%.

[0084] The bio-based modifier is lignin sulfonate;

[0085] The plasticizer is dipropylene glycol dibenzoate;

[0086] The tackifier is rosin glycerol ester;

[0087] The initiator is ammonium persulfate, and the initiator is prepared into an initiator solution containing 10% water using deionized water;

[0088] The emulsifier is a compound emulsifier of anionic and nonionic emulsifiers, which is composed of sodium dodecyl sulfate and nonylphenol polyoxyethylene ether in a mass ratio of 1:1.5.

[0089] The wetting agent is an organically modified siloxane;

[0090] The defoamer is a mineral oil-based defoamer;

[0091] The preservative is an isothiazolinone;

[0092] The pH adjuster is sodium bicarbonate.

[0093] Step 2, prepare polyvinyl alcohol aqueous solution:

[0094] Add deionized water (60% of the total deionized water) to the reactor, heat to 90℃ and start stirring (150-200 r / min). Slowly add PVA, controlling the feeding speed to be uniform and avoid clumping. Maintain the temperature at 85-90℃ and stir for 1.5-2.5 hours until the PVA is completely dissolved, forming a uniform and transparent PVA aqueous solution (20% solid content). Turn off the heating and allow it to cool naturally to room temperature (25±2℃) for later use.

[0095] Step 3, Preparation of the composite adhesive:

[0096] Premixing: Add the VAE emulsion to another reactor, turn on the stirrer, control the speed at 100-150 r / min, and stir for 10-20 min;

[0097] Slowly add the PVA aqueous solution prepared in step 2 into the reaction vessel. After the addition is completed, continue to add emulsifier, initiator accounting for 50% of the total initiator solution, and deionized water into the vessel. Keep the stirring speed constant and continue stirring for 60-70 minutes to allow PVA to be fully adsorbed on the surface of VAE latex particles and form a stable VAE-PVA composite emulsion system.

[0098] Add the bio-based modifier and plasticizer sequentially to the VAE-PVA composite emulsion system reactor, and stir for 50-70 minutes to allow the bio-based modifier to fully integrate with the VAE-PVA composite emulsion system, forming a hydrogen bond network and improving the system's water resistance and initial tack. After stirring, add the tackifying resin and the remaining initiator solution, and continue stirring for 40-60 minutes until the tackifying resin is completely dissolved and evenly dispersed.

[0099] Add a wetting agent to the reaction vessel and stir for 8-12 minutes to ensure uniform dispersion of the wetting agent and reduce the surface tension of the composite emulsion; then add the preservative and defoamer and stir for 10-20 minutes to ensure uniform dispersion of the preservative and defoamer, achieving defoaming and antibacterial effects, and obtain the composite emulsion.

[0100] Step 4, Post-processing:

[0101] Add deionized water and pH adjuster to the composite adhesive solution, stir for 20-30 minutes, and adjust the solid content, viscosity and pH of the composite adhesive solution to meet the preset requirements; filter with a 100-200 mesh filter to remove impurities and a small amount of undissolved particles to obtain the packaging adhesive for high-speed cigarette packaging machines, and seal and store for later use.

[0102] Comparative Example 1

[0103] Step 1, Raw material preparation:

[0104] 510 kg of VAE emulsion, 180 kg of PVA aqueous solution, 260 kg of deionized water, 6 kg of plasticizer, 50 kg of thickener, 12 kg of emulsifier, 4 kg of initiator, 5 kg of wetting agent, 5 kg of defoamer, 5 kg of preservative, and 5 kg of pH adjuster.

[0105] The VAE emulsion has an ethylene content of 20% and a solids content of 55%.

[0106] The degree of alcoholysis of the polyvinyl alcohol aqueous solution is 90%, the degree of polymerization is about 2000, and the solid content is 20%.

[0107] The plasticizer is dipropylene glycol dibenzoate;

[0108] The tackifier is rosin glycerol ester;

[0109] The initiator is ammonium persulfate, and the initiator is prepared into an initiator solution containing 10% water using deionized water;

[0110] The wetting agent is an organically modified siloxane;

[0111] The defoamer is a mineral oil-based defoamer;

[0112] The preservative is an isothiazolinone;

[0113] The pH adjuster is sodium bicarbonate.

[0114] Step 2: Prepare an aqueous solution of polyvinyl alcohol;

[0115] Add deionized water (60% of the total deionized water) to the reactor, heat to 90℃ and start stirring (150-200 r / min). Slowly add PVA, controlling the feeding speed to be uniform and avoid clumping. Maintain the temperature at 85-90℃ and stir for 1.5-2.5 hours until the PVA is completely dissolved, forming a uniform and transparent PVA aqueous solution (20% solid content). Turn off the heating and allow it to cool naturally to room temperature (25±2℃) for later use.

[0116] Step 3, Preparation of the composite adhesive:

[0117] Add the VAE emulsion to another reactor, turn on the stirrer, control the speed at 100-150 r / min, and stir for 10-20 min;

[0118] Slowly add the PVA aqueous solution prepared in step 2 into the reactor. After the addition is complete, continue to add emulsifier, initiator solution and deionized water to the reactor. Keep the stirring speed constant and continue stirring for 60-70 minutes to allow PVA to be fully adsorbed on the surface of VAE latex particles and form a stable VAE-PVA composite emulsion system. After stirring, add tackifying resin and continue stirring for 40-60 minutes until the tackifying resin is completely dissolved and evenly dispersed.

[0119] Add a wetting agent to the reaction vessel and stir for 8-12 minutes to ensure uniform dispersion of the wetting agent and reduce the surface tension of the composite emulsion; then add the preservative and defoamer and stir for 10-20 minutes to ensure uniform dispersion of the preservative and defoamer, achieving defoaming and antibacterial effects, and obtain the composite emulsion.

[0120] Step 4, Post-processing:

[0121] Add deionized water and pH adjuster to the composite adhesive solution, stir for 20-30 minutes, and adjust the solid content, viscosity and pH of the composite adhesive solution to meet the preset requirements; filter with a 100-200 mesh filter to remove impurities and a small amount of undissolved particles to obtain the packaging adhesive for high-speed cigarette packaging machines, and seal and store for later use.

[0122] Test case

[0123] 1. Performance testing of packaging adhesive for high-speed cigarette packaging machines:

[0124] The performance of the ultra-high-speed packaging adhesives prepared in Examples 1-2 and Comparative Example 1 was tested, and the test results are shown in Table 1 below.

[0125] The testing standards for viscosity are GB / T 2794-2022; for solids content, YC / T 188-2004; for pH value, GB / T 14518-1993; for dilute stability, GB / T 14518-1993; for thermal stability, GB / T 14518-1993; for minimum film-forming temperature, GB / T 14518-1993; for glass transition temperature, GB / T 19466.2-2004; and for VOCs, YC / T399-2011.

[0126] Table 1. Comparison of packaging adhesive performance between Examples 1-2 and Comparative Example 1

[0127]

[0128] Table 1 shows that the viscosity of the packaging adhesive of this invention is 289-310 mPa·s, the solid content is 48.9-50.6%, the pH value is 5.1-5.3, the dilution stability is 3.1-3.4, the cold stability is no skinning and no sedimentation, the minimum film-forming temperature is 0-1℃, the glass transition temperature is 0-2℃, and VOCs ≤12g / L, even reaching VOCs ≤7g / L. Examples 1 and 2 both added bio-based modifiers to their formulations, but in different proportions, while Comparative Example 3 did not add any. From Table 1 above, it can be seen that the ultra-high-speed packaging adhesive with added bio-based modifiers exhibits improved dilution stability and cold / heat stability. This is because the introduction of hydrophobic groups improves the water resistance of the emulsion system; the bio-based material and monomers construct a three-dimensional covalent network structure, strengthening the chemical bond strength and improving the temperature resistance. The increased proportion of recycled carbon in bio-based modified packaging materials significantly improves the environmental performance of cigarette packs. Recycled carbon has a wide range of sources, and its cost can be reduced to some extent.

[0129] 2. The application performance of the ultra-high-speed packaging adhesives used in Examples 1-2 and Comparative Example 3 was tested, and the specific details are shown in Table 2 below.

[0130] The testing standards for substrate adhesion are based on GB / T 9286-2021, using the scribing method; the testing standards for surface drying time are based on GB / T 1728-2020, using the finger touch method; the testing standards for open time are based on GB / T 1728-2020, using the thick-layer drying method; the testing standards for folding resistance are based on GB / T 2790-1998, using 180° folding; and the testing standards for weather resistance are based on YC / T208-2014, using 40℃±2℃, RH90%±5%, 168h (7d), industry-standard accelerated conditions.

[0131] Table 2 Comparison of the application performance of packaging adhesives in Examples 1-2 and Comparative Example 3

[0132]

[0133] Table 2 shows that the substrate adhesion of the packaging adhesive of this invention is grade 0, the surface drying time is 4-5 min, the open time is 8-12 h, the folding resistance is 29-32 times, and there is no bubbling, delamination, powdering, or yellowing. The peel strength is ≥86%. In practical applications, the ultra-high-speed packaging adhesives of Examples 1-2, which introduced bio-based modifiers, have better performance than the ultra-high-speed packaging adhesive of Comparative Example 1, which did not add bio-based additives. Furthermore, the use of bio-based additives in Examples 1-2 significantly reduced VOC emissions when using the packaging adhesives, further protecting the health and environment of workshop workers. This further demonstrates that introducing bio-based modifiers to prepare packaging adhesives is beneficial both in terms of the adhesive's performance and its application.

[0134] This invention optimizes the viscosity and drying speed of the adhesive solution, ensuring precise compatibility with the coating system of the GDH1000 packaging machine and its high-speed operation of 1000 packs / minute. This avoids uneven coating, stringing, and unwinding issues, improving equipment stability. It also enhances the wettability and adhesion strength of the adhesive solution to cigarette packaging paper (especially smooth materials), ensuring no openings, pop-ups, or curling edges after high-speed bonding, significantly improving packaging pass rates. Furthermore, it improves the temperature and humidity resistance of the adhesive solution, maintaining stable adhesion under various environmental conditions while ensuring the solution is odorless and residue-free, fully complying with hygiene and safety standards for cigarette products. By using readily available and environmentally friendly raw materials and optimizing the preparation process, it reduces production costs while maintaining core product performance, enabling large-scale industrial production and widespread application.

[0135] The main reaction mechanism for preparing the packaging adhesive in this invention is as follows: VAE emulsion is the main film-forming substance, which forms a stable water-based emulsion under the action of free radical initiation in the composite emulsion system (the role of the initiator); in the composite emulsion system, PVA is adsorbed on the surface of VAE latex particles in the form of a protective colloid, and forms a stable composite structure with VAE segments through intermolecular hydrogen bonding, thereby regulating the viscosity, solid content and rheological properties of the adhesive and adapting it to high-speed spraying conditions.

[0136] Bio-based modifiers (such as lignin sulfonates) form intermolecular hydrogen bonds and mild covalent crosslinks with the VAE-PVA composite emulsion system, constructing a three-dimensional network structure. This introduces hydrophobic groups to enhance the water resistance, temperature resistance, and cohesiveness of the adhesive layer, while simultaneously reducing VOC emissions. Tackifying resins and environmentally friendly plasticizers, through the synergistic effect of molecular chain plasticization and interfacial tackification, lower the glass transition temperature of the system, improving initial tack and film flexibility.

[0137] The wetting agent significantly reduces the surface tension of the adhesive, enabling rapid wetting and uniform spreading of the adhesive on the surface of tobacco packaging substrates such as metallized paper and printing paper. High-strength adhesion is achieved through interfacial van der Waals forces, hydrogen bonding, and physical interlocking. The adhesive curing process primarily involves physical film formation through water evaporation, with latex particles fusing to form a continuous and dense film. No toxic crosslinking agents such as formaldehyde, isocyanates, or aziridine are involved in the reaction throughout the entire process. Ultimately, this achieves a comprehensive effect of being suitable for ultra-high-speed packaging of 1000 packs / minute, providing stable adhesion, and being environmentally friendly.

[0138] The advantages of the packaging adhesive obtained by this invention are:

[0139] 1. Extremely environmentally friendly: It uses renewable bio-based epoxidized lignin to replace traditional toxic cross-linking agents, achieving green production without formaldehyde, aziridine, or isocyanates, and meeting the food contact safety standards for cigarette packaging.

[0140] 2. High-performance breakthrough: Through the construction of a covalent cross-linked network, the packaging adhesive has excellent weather resistance. It does not re-stick or change color after 30 minutes in a humid and hot environment. It has excellent water resistance. After 24 hours of immersion, the inner film does not bubble or delaminate, and the strength retention rate is ≥92%.

[0141] 3. Process adaptability: The adhesive viscosity is stable, and the surface drying and open time are suitable for the GDH1000 high-speed cigarette packaging machine production line; it has extremely high adhesion to the substrate, improving the refinement and reliability of the finished cigarette packaging.

[0142] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes can be made in form and detail without departing from the scope of the present invention.

Claims

1. A packaging adhesive for a high-speed cigarette packaging machine, characterized in that, Included by weight percentage: 20-50% vinyl acetate-ethylene copolymer emulsion, 50-10% polyvinyl alcohol solution, 2-6% bio-based modifier, 0.03-0.1% plasticizer, 2-5% tackifying resin, 0.5-2% emulsifier, 0.1-0.5% initiator, 0.1-0.5% wetting agent, 0.1-0.5% defoamer, 0.5-1% preservative and 15-25% deionized water.

2. The packaging adhesive for a high-speed cigarette packaging machine according to claim 1, characterized in that, Included by weight percentage: The mixture contains 50% vinyl acetate-ethylene copolymer emulsion, 10% polyvinyl alcohol solution, 6.4% bio-based modifier, 0.1% plasticizer, 5% tackifying resin, 2% emulsifier, 0.5% initiator, 0.5% wetting agent, 0.5% defoamer, 1% preservative and 24% deionized water.

3. The packaging adhesive for a high-speed cigarette packaging machine according to claim 1 or claim 2, characterized in that, The vinyl acetate-ethylene copolymer emulsion has an ethylene content of 18-25% and a solids content of 50-55%.

4. The packaging adhesive for a high-speed cigarette packaging machine according to claim 1 or claim 2, characterized in that, The polyvinyl alcohol solution has a degree of alcoholysis of 87-99%, a degree of polymerization of 1700-2400, and a solid content of 18-22%.

5. The packaging adhesive for a high-speed cigarette packaging machine according to claim 1 or claim 2, characterized in that, The bio-based modifiers include bio-based polyols, lignin sulfonates, or starch derivatives.

6. The packaging adhesive for a high-speed cigarette packaging machine according to claim 1 or claim 2, characterized in that, The plasticizer includes dipropylene glycol dibenzoate, epoxidized soybean oil, or triacetyl ester; The tackifying resin includes hydrogenated rosin, rosin glycerol ester, or terpene resin; The emulsifier includes anionic emulsifiers and nonionic emulsifiers, and the mass ratio of the anionic emulsifier to the nonionic emulsifier is 1:1.

5. The initiator includes ammonium persulfate, potassium persulfate, or sodium persulfate; The wetting agent includes organically modified siloxanes or acetylenic diols. The defoamer includes polyether siloxane or mineral oil-based defoamers; The preservatives include isothiazol quinolinone preservatives.

7. The packaging adhesive for a high-speed cigarette packaging machine according to claim 1 or claim 2, characterized in that, The polyvinyl alcohol aqueous solution is obtained by mixing polyvinyl alcohol and deionized water.

8. A method for preparing packaging adhesive for a high-speed cigarette packaging machine according to any one of claims 1-7, characterized in that, Includes the following steps: A VAE-PVA composite emulsion system in which polyethylene solution is adsorbed onto the surface of vinyl acetate-ethylene copolymer latex particles is obtained by mixing and stirring vinyl acetate-ethylene copolymer emulsion, emulsifier, initiator solution accounting for 50% of the total initiator solution and deionized water; The VAE-PVA composite emulsion system, bio-based modifier, and plasticizer are mixed and stirred. Then, tackifying resin, the remaining initiator, wetting agent, preservative, and defoamer are added in batches to obtain a composite adhesive. The composite adhesive is then post-treated to obtain a packaging adhesive.

9. A method for preparing packaging adhesive for a high-speed cigarette packaging machine according to claim 8, characterized in that, The initiator solution is obtained by mixing an initiator with deionized water, and the mass ratio of the initiator to deionized water is 9:

1.

10. A method for preparing packaging adhesive for a high-speed cigarette packaging machine according to claim 8, characterized in that, The post-processing includes adjusting the solid content, viscosity and pH value of the composite adhesive solution using deionized water and a pH adjuster, and filtering it through a 100-200 mesh filter to obtain the packaging adhesive.

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