High-performance corrugated carton with waterproof and antibacterial functions and preparation process thereof

Abstract

The application discloses a high-performance corrugated carton with waterproof and antibacterial functions and a preparation process thereof, and the process comprises the following steps: S1, providing a corrugated paperboard substrate; S2, coating a barrier-enhanced coating liquid on the inner and outer surfaces of the corrugated paperboard substrate respectively, and forming a barrier-enhanced coating layer after solidification; S3, coating a composite antibacterial coating liquid, and forming a composite antibacterial coating layer after solidification to obtain a composite corrugated paperboard; and S4, using the composite corrugated paperboard to make a corrugated carton. The composite antibacterial coating layer can improve the waterproof performance of the composite corrugated paperboard and endow the composite corrugated paperboard with excellent antibacterial performance. Through cooperation of the barrier-enhanced coating layer and the composite antibacterial coating layer and with the excellent barrier effect of the barrier-enhanced coating layer, the waterproof performance of the composite corrugated paperboard can be further improved while avoiding the risk that active oxygen brought by the composite antibacterial coating layer may damage the performance of the corrugated paperboard substrate, and the mechanical strength of the composite corrugated paperboard can be improved, so that the service life of the composite corrugated paperboard can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of corrugated paper, in particular to a high-performance corrugated paper box with waterproof and antibacterial functions and a preparation process thereof. BACKGROUND

[0002] Corrugated paper boxes are the most widely used packaging products, which are made of corrugated paperboard through die cutting, indentation, nailing or sticking. Corrugated paperboard is a multi-layer adhesive body, which is usually composed of at least one layer of corrugated core paper (commonly known as "corrugated paper core") and one layer of inner paperboard and one layer of surface paperboard, and has high mechanical strength. The corrugated paperboard has the following three advantages as a packaging material: 1) low production cost, the packaging container made of it is light in weight, foldable, convenient for storage and transportation, and the raw paper cost is much lower than that of other materials such as plastic and metal; 2) convenient for recycling, in line with green packaging requirements, the corrugated paperboard can be used as raw material for pulp or molding production after recycling, and can be used to produce corrugated paperboard again; 3) easy to process and shape, which can be processed into packaging containers required by commodities through die cutting, indentation, folding and other steps, and the operation is simple and easy. The production process of corrugated paperboard has shown high automation and flow operation, and the continuous production line completes corrugated pressing, gluing, lamination, drying and shaping on the same machine, which has fast production rate, low cost and can ensure the quality of corrugated paperboard (CN110306380B A waterproof and flame-retardant coating for corrugated paperboard and a preparation method thereof).

[0003] The conventional corrugated paperboard has hygroscopicity, which will cause a large decrease in mechanical properties on one hand, and on the other hand, the humid environment is easy to breed bacteria and mold, which poses a risk of harming the packaged goods and even human health.

[0004] Coating a waterproof coating on the surface of the corrugated paperboard is a common method to improve its waterproof performance, such as patent CN115897284B A production method of waterproof and wear-resistant corrugated paperboard, CN116397461B A waterproof and flame-retardant composite corrugated paperboard and its composite process, CN117966517B A waterproof and flame-retardant corrugated paper and its preparation method; but the antibacterial performance of the corrugated paperboard is not improved in these patents, and the waterproof coating cannot achieve "water dripping without sticking", and bacteria are still easy to breed when the environment is humid or when it is wet. In the usual range of temperature and humidity, the higher the temperature and humidity, the more conducive to the breeding and reproduction of most bacteria and fungi.

[0005] Patent CN107447592B discloses a hydrophobic antibacterial agent for corrugated board and a hydrophobic antibacterial enhanced corrugated board and a preparation method, taking fumed silica as a carrier, loading silane coupling agent and nano silver ions, and combining hydrophobic and antibacterial dual functions, and the hydrophobic and antibacterial properties are excellent. However, in the face of the characteristics that the higher the temperature and humidity in a certain range, the easier it is to breed bacteria, the patent does not provide a reliable solution.

[0006] Therefore, it is necessary to improve the prior art to provide a more reliable solution. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a high-performance corrugated paper box with waterproof and antibacterial functions and a preparation process thereof.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is as follows: the first aspect of the present application provides a preparation process of a high-performance corrugated paper box with waterproof and antibacterial functions, comprising the following steps:

[0009] S1, providing a corrugated paper board substrate;

[0010] S2, coating a barrier-enhancing coating liquid on the inner and outer surfaces of the corrugated paper board substrate, respectively, to form a barrier-enhancing coating layer after curing;

[0011] S3, coating a composite antibacterial coating liquid on the surface of the barrier-enhancing coating layer, to form a composite antibacterial coating layer after curing, to obtain a composite corrugated paper board;

[0012] S4, using the composite corrugated paper board to make the high-performance corrugated paper box with waterproof and antibacterial functions;

[0013] The composite antibacterial coating liquid comprises the following raw material components by weight: modified epoxy resin emulsion 80-120 parts, antibacterial agent 8-17 parts, curing agent 15-28 parts, and organic solvent 65-105 parts.

[0014] The antibacterial agent is prepared by the following method:

[0015] S3-1, preparing amino-functionalized nanoporous silica;

[0016] S3-2, preparing titanium-doped carbon dots;

[0017] S3-3, taking amino-functionalized nanoporous silica as a carrier and titanium-doped carbon dots as an active antibacterial component, loading titanium-doped carbon dots on the amino-functionalized nanoporous silica, to obtain carbon dot-silica composite particles;

[0018] S3-4, coating a self-adaptive protective film on the surface of the carbon dot-silica composite particles to obtain the antibacterial agent.

[0019] Preferably, step S3-1 is specifically:

[0020] S3-1-1, take 3-12 mL of ethanol, 0.03-0.18 g of cetyl trimethyl ammonium bromide into 20-80 mL of deionized water, stir for 5-30 min, then add 1-4 mL of triethanolamine dropwise, stir for 5-30 min, and then heat to 55-70℃, add a mixture of 1.5-6 mL of tetraethyl orthosilicate and 0.15-0.6 mL of aminopropyl methyl diethoxysilane under stirring at 1000-4000 rpm, maintain the current temperature, and react for 2 h under stirring at 500-1000 rpm;

[0021] S3-1-2, transfer the product obtained in step S3-1-1 to a reaction kettle, react at 110-130℃ for 24-72 h, cool to room temperature, centrifugal filtration, and then add the solid product into a mixed washing liquid composed of 15-60 mL of ethanol and 100-400 mL of hydrochloric acid with a concentration of 5 wt%, ultrasonic for 15-60 min, filter, wash the solid product with ethanol again, and dry at 50-80℃ until constant weight to obtain aminated nanoporous silica.

[0022] Preferably, step S3-2 is specifically:

[0023] S3-2-1, take 0.6-2.4 g of chitosan, add into 50-150 mL of an aqueous solution of acetic acid with a concentration of 1-3 wt%, and stir for 3-10 min to obtain a mixed liquid 1;

[0024] S3-2-2, take 0.29-1.186 g of tetracarboxyphenyl porphyrin, 0.384-1.536 g of citric acid, and 0.234-0.936 g of titanium oxalate, add into 50-200 mL of deionized water, and stir for 5-20 min to obtain a mixed liquid 2;

[0025] S3-2-3, add the mixed liquid 1 into the mixed liquid 2, stir for 10-40 min to obtain a precursor liquid, transfer the precursor liquid into a reaction kettle with a polytetrafluoroethylene liner, react at 170-210℃ for 6-24 h, cool to room temperature after the reaction is completed, filter the product with a filter membrane with a pore size of 0.22 μm, dialyze the filtrate in a dialysis bag with a molecular weight cut-off of 1000D in deionized water for 48 h, take the dialysate in the dialysis bag, rotary evaporate, and then freeze-dry to obtain titanium-doped carbon dots.

[0026] Preferably, step S3-3 is specifically:

[0027] S3-3-1, take 0.5-2 g of aminated nanoporous silica, add into 25-100 mL of deionized water, and ultrasonic for 5-30 min to obtain a silica dispersion liquid;

[0028] S3-3-2, 0.225-0.9 g titanium-doped carbon dots were taken into 25-100 mL deionized water, and ultrasonic dispersion was performed for 5-30 min to obtain a carbon dot dispersion liquid;

[0029] S3-3-3, the carbon dot dispersion liquid was added to the silica dispersion liquid under stirring, and the shaking table was shaken at 50-70 °C and 80-200 rpm for 12-48 h, then filtration was performed, and the solid product was vacuum dried at 60-80 °C for 6-24 h to obtain carbon dot-silica composite particles.

[0030] Preferably, step S3-4 is specifically as follows:

[0031] 0.15-0.6 g of corn starch and 0.35-1.4 g of β-cyclodextrin were taken into 50-200 mL distilled water, ultrasonic dispersion was performed for 10-30 min, heating was performed in a boiling water bath under stirring for 30-90 min, stirring was maintained, 0.25-1 g of carbon dot-silica composite particles were added, and after cooling to 60-70 °C, stirring was continued for 0.5-2 h, and then standing was performed at 2-10 °C for 12-48 h, filtration was performed, the solid product was washed with ethanol, and vacuum freeze-drying was performed to obtain an antibacterial agent.

[0032] Preferably, the modified epoxy resin emulsion is prepared by the following method:

[0033] 2.5-10 g of amino silicone oil and 0.35-1.5 g of OP-10 were taken into 20 mL of toluene, stirring was performed at 60-70 °C and 1000-4000 rpm for 30-90 min, then 3-12 g of epoxy resin E44 and 0.05-0.2 g of 2-lauryl acid-2-butyl tin were added, and heating was performed under reflux at 72-80 °C for 3-8 h to obtain a modified epoxy resin emulsion.

[0034] Preferably, the organic solvent is toluene, and the curing agent is isorone diamine;

[0035] The composite antibacterial coating liquid is prepared by the following method:

[0036] 1) Toluene was divided into two parts, the antibacterial agent was added to the first part of toluene, ultrasonic dispersion was performed for 5-30 min to obtain an antibacterial agent dispersion liquid;

[0037] 2) The modified epoxy resin emulsion was added to the second part of toluene, stirring was performed for 5-20 min, the antibacterial agent dispersion liquid was added under stirring, stirring was performed for 10-45 min, then isorone diamine was added, and stirring was continued for 3-10 min to obtain a composite antibacterial coating liquid.

[0038] Preferably, the barrier-enhancing coating liquid is prepared by the following method:

[0039] S2-1, take 2.5-10 g of graphene oxide into a mixed acid composed of 25-100 mL of 10% H2O2 and 50-300 mL of 95 wt% concentrated sulfuric acid, heat under reflux at 70-85°C for 4-12 h, filter, wash the solid product with deionized water until neutral, and vacuum dry at 60-90°C to constant weight to obtain pretreated graphene oxide;

[0040] S2-2, take 0.15-0.6 g of pretreated graphene oxide into 225-900 mL of dimethylacetamide, ultrasonically disperse for 1-4 h, then add 17.5-70 g of ethylenediamine and 3-6 g of dicyclohexylcarbodiimide, ultrasonically disperse for 5-30 min, then seal and react at 125-140°C for 24-72 h, after the reaction is completed, add 50-200 mL of ethanol to the product, stand for 6-24 h, discard the supernatant, filter the lower layer precipitate, wash the solid product with deionized water and ethanol in turn, and vacuum dry at 90-100°C for 6-24 h to obtain modified graphene oxide;

[0041] S2-2, take 0.5-2 g of modified graphene oxide into 25-100 mL of deionized water, ultrasonically disperse for 30-90 min to obtain a modified graphene oxide dispersion;

[0042] S2-2, take 2.5-10 g of polyvinyl alcohol, 0.4-1.6 g of sorbitol, and 0.25-1 g of Tween 80 into 50-150 mL of deionized water, stir at 70-85°C for 5-20 min, then add the modified graphene oxide dispersion under stirring, ultrasonically disperse for 30-90 min to obtain a barrier-enhancing coating liquid.

[0043] Preferably, the preparation process of the waterproof and antibacterial high-performance corrugated paper box comprises the following steps:

[0044] S1, providing a corrugated paperboard substrate;

[0045] S2, coating a barrier-enhancing coating liquid on the inner and outer surfaces of the corrugated paperboard substrate, and drying at 50-80°C for 15-60 min to form a barrier-enhancing coating layer with a thickness of 0.1-0.5 mm;

[0046] S3, coating a composite antibacterial coating liquid on the surface of the barrier-enhancing coating layer, and curing at 60-80°C for 3-8 h to form a composite antibacterial coating layer with a thickness of 0.25-1 mm, to obtain a composite corrugated paperboard;

[0047] S4, using the composite corrugated paperboard to make the waterproof and antibacterial high-performance corrugated paper box through die cutting, scoring, and nailing / gluing.

[0048] The second aspect of the present application provides a high-performance corrugated carton with waterproof and antibacterial functions, which is prepared by the above process.

[0049] The present application has the following advantages:

[0050] The present application provides a high-performance corrugated carton with waterproof and antibacterial functions. In the present application, the addition of an antibacterial agent can impart excellent antibacterial properties to the corrugated paperboard. Moreover, the antibacterial properties can be self-adaptively adjusted within a certain range according to different environmental temperatures and humidities. Specifically, when the environmental temperature and / or humidity increase, the antibacterial properties provided by the antibacterial agent will be self-adaptively enhanced, so as to well cope with the characteristic that the higher the temperature and humidity within a certain range, the more likely it is for bacteria to breed on the surface of the corrugated carton, and long-acting antibacterial effects can be provided.

[0051] The present application can improve the waterproof performance of the composite corrugated paperboard through the composite antibacterial coating, impart excellent antibacterial properties to it through the generation of active oxygen substances, and further improve the waterproof performance of the composite corrugated paperboard while avoiding the risk that the active oxygen brought by the composite antibacterial coating may damage the performance of the corrugated paperboard substrate, by virtue of the excellent barrier effect of the barrier-enhanced coating. Moreover, the mechanical strength of the composite corrugated paperboard can be improved, and the service life thereof can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 Test results of the active oxygen release amount of the antibacterial agent prepared for Example 1 under different relative humidities;

[0053] Figure 2 Test results of the active oxygen release amount of the antibacterial agent prepared for Example 1 under different temperatures;

[0054] Figure 3 Infrared absorption spectrum of the titanium-doped carbon dots prepared for Example 1;

[0055] Figure 4 Test results of the antibacterial properties. DETAILED DESCRIPTION

[0056] The present application will be further described in detail below in combination with examples, so as to enable one skilled in the art to implement the present application according to the description.

[0057] It should be understood that the terms such as "have", "contain" and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0058] The test methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are commercially available unless otherwise specified. The specific conditions not specified in the following examples are carried out under conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are conventional products that can be obtained by commercial purchase unless otherwise specified.

[0059] The application provides a preparation process of a high-performance corrugated paper box with waterproof and antibacterial functions, comprising the following steps:

[0060] S1, providing a corrugated paperboard substrate;

[0061] S2, coating a barrier-enhancing coating liquid on the inner surface and the outer surface of the corrugated paperboard substrate respectively, drying at 50-80 DEG C for 15-60 min, and forming a barrier-enhancing coating layer with a thickness of 0.1-0.5 mm;

[0062] S3, coating a composite antibacterial coating liquid on the surface of the barrier-enhancing coating layer, curing at 60-80 DEG C for 3-8 h, forming a composite antibacterial coating layer with a thickness of 0.25-1 mm, and obtaining a composite corrugated paperboard;

[0063] S4, using the composite corrugated paperboard to make a high-performance corrugated paper box with waterproof and antibacterial functions through die cutting, indentation, box nailing / adhesion.

[0064] In the application, the corrugated paperboard substrate can be a conventional commercially available product or a self-made product based on a conventional method.

[0065] In the application, the barrier-enhancing coating liquid is prepared by the following method:

[0066] S2-1, 2.5-10 g of graphene oxide is taken into a mixed acid composed of 25-100 mL of 10% H2O2 and 50-300 mL of 95 wt% concentrated sulfuric acid, heated and refluxed at 70-85 DEG C for 4-12 h, filtered, and the solid product is washed to neutral with deionized water and vacuum dried at 60-90 DEG C to constant weight to obtain pretreated graphene oxide;

[0067] S2-2, 0.15-0.6 g of pretreated graphene oxide is added into 225-900 mL of dimethylacetamide (DMF) and ultrasonically dispersed for 1-4 h, then 17.5-70 g of ethylenediamine (EDA) and 3-6 g of dicyclohexyl carbodiimide (DCC) are added, ultrasonically dispersed for 5-30 min, then sealed and reacted at 125-140 DEG C for 24-72 h, 50-200 mL of ethanol is added to the product after the reaction is completed, and the mixture is left to stand for 6-24 h, the supernatant is discarded, the lower layer is filtered, and the solid product is washed with deionized water and ethanol in sequence, and vacuum dried at 90-100 DEG C for 6-24 h to obtain modified graphene oxide.

[0068] S2-2, take 0.5-2g modified graphene oxide into 25-100mL deionized water, ultrasonic dispersion for 30-90min, to obtain modified graphene oxide dispersion liquid;

[0069] S2-2, take 2.5-10g polyvinyl alcohol, 0.4-1.6g sorbitol, 0.25-1g Tween 80 into 50-150mL deionized water, stirring at 70-85℃ for 5-20min, then under stirring, add modified graphene oxide dispersion liquid, ultrasonic dispersion for 30-90min, to obtain barrier enhanced coating liquid.

[0070] In the application, the composite antibacterial coating liquid comprises the following raw material components by weight: modified epoxy resin emulsion 80-120 parts, antibacterial agent 8-17 parts, curing agent 15-28 parts, organic solvent 65-105 parts.

[0071] In the preferred embodiment, the organic solvent is toluene, and the curing agent is isorone diamine.

[0072] In the preferred embodiment, the composite antibacterial coating liquid is prepared by the following method:

[0073] 1) Divide the toluene into two parts, add the antibacterial agent into the first part of toluene, and ultrasonic dispersion for 5-30min to obtain an antibacterial agent dispersion liquid;

[0074] 2) Add the modified epoxy resin emulsion into the second part of toluene, stir for 5-20min, add the antibacterial agent dispersion liquid under stirring, stir for 10-45min, then add isorone diamine, continue to stir for 3-10min to obtain the composite antibacterial coating liquid.

[0075] In the application, the modified epoxy resin emulsion is prepared by the following method:

[0076] Take 2.5-10g amino silicone oil, 0.35-1.5g OP-10 into 20mL toluene, stir at 60-70℃ and 1000-4000rpm for 30-90min, then add 3-12g epoxy resin E44, 0.05-0.2g 2-lauric acid-2-butyl tin (DBTDL), heat and reflux at 72-80℃ for 3-8h to obtain the modified epoxy resin emulsion.

[0077] In the application, the antibacterial agent is prepared by the following method:

[0078] S3-1, prepare aminoized nanoporous silica:

[0079] S3-1-1, take 3-12 mL of ethanol, 0.03-0.18 g of cetyl trimethyl ammonium bromide into 20-80 mL of deionized water, stir for 5-30 min, then add 1-4 mL of triethanolamine dropwise, stir for 5-30 min, heat to 55-70℃, add 1.5-6 mL of a mixture of tetraethyl orthosilicate and 0.15-0.6 mL of aminopropylmethyldiethoxysilane under stirring at 1000-4000 rpm, maintain the current temperature, react for 2 h under stirring at 500-1000 rpm;

[0080] S3-1-2, transfer the product obtained in step S3-1-1 to a reaction kettle, react for 24-72 h at 110-130℃, cool to room temperature, centrifugal filtration, add the solid product into 15-60 mL of a mixed washing liquid composed of 5 wt% hydrochloric acid and 100-400 mL of ethanol, ultrasonic for 15-60 min, filter, wash the solid product with ethanol again, dry at 50-80℃ until constant weight, to obtain aminated nanoporous silica.

[0081] S3-2, prepare titanium-doped carbon dots:

[0082] S3-2-1, take 0.6-2.4 g of chitosan, add into 50-150 mL of 1-3 wt% acetic acid aqueous solution, stir for 3-10 min, to obtain a mixed liquid 1;

[0083] S3-2-2, take 0.29-1.186 g of tetracarboxyphenyl porphyrin, 0.384-1.536 g of citric acid, 0.234-0.936 g of titanium oxalate into 50-200 mL of deionized water, stir for 5-20 min, to obtain a mixed liquid 2;

[0084] S3-2-3, add the mixed liquid 1 into the mixed liquid 2, stir for 10-40 min, to obtain a precursor liquid, transfer the precursor liquid into a reaction kettle with a polytetrafluoroethylene liner, react for 6-24 h at 170-210℃, after the reaction is completed, cool to room temperature, filter the product with a filter membrane of 0.22 μm, dialyze the filtrate in a dialysis bag with a molecular weight cut-off of 1000D in deionized water for 48 h, take the dialysate in the dialysis bag, rotary evaporate and freeze-dry, to obtain titanium-doped carbon dots.

[0085] S3-3, take the aminated nanoporous silica as a carrier, the titanium-doped carbon dots as an active antibacterial component, load the titanium-doped carbon dots on the aminated nanoporous silica, to obtain carbon dot-silica composite particles:

[0086] S3-3-1, take 0.5-2 g of aminated nanoporous silica into 25-100 mL of deionized water, ultrasonic dispersion for 5-30 min, to obtain a silica dispersion liquid;

[0087] S3-3-2, 0.225-0.9 g of titanium-doped carbon dots were taken and added to 25-100 mL of deionized water, and ultrasonic dispersion was performed for 5-30 min to obtain a carbon dot dispersion liquid;

[0088] S3-3-3, the carbon dot dispersion liquid was added to the silica dispersion liquid under stirring, and the shaking table was shaken at 50-70 °C and 80-200 rpm for 12-48 h, filtration was performed, and the solid product was vacuum dried at 60-80 °C for 6-24 h to obtain carbon dot-silica composite particles.

[0089] S3-4, a self-adaptive protective film was coated on the surface of the carbon dot-silica composite particles:

[0090] 0.15-0.6 g of corn starch and 0.35-1.4 g of β-cyclodextrin were taken and added to 50-200 mL of distilled water, ultrasonic dispersion was performed for 10-30 min, heating was performed in a boiling water bath under stirring for 30-90 min, stirring was maintained, 0.25-1 g of carbon dot-silica composite particles were added, stirring was continued for 0.5-2 h after cooling to 60-70 °C, and standing was performed at 2-10 °C for 12-48 h, suction filtration was performed, the solid product was washed with ethanol, and vacuum freeze-drying was performed to obtain an antibacterial agent.

[0091] In the present application, the waterproof performance of the composite corrugated paperboard can be improved by the composite antibacterial coating, excellent antibacterial performance can be imparted by generating reactive oxygen substances, and the waterproof performance of the composite corrugated paperboard can be further improved while avoiding the risk that the active oxygen brought by the composite antibacterial coating may damage the performance of the corrugated paperboard substrate, and the mechanical strength of the composite corrugated paperboard can be improved by the cooperation of the barrier enhancement coating and the composite antibacterial coating, and the excellent barrier effect of the barrier enhancement coating. The main effects of the composite antibacterial coating and the barrier enhancement coating are described below.

[0092] I. Main effects of the composite antibacterial coating:

[0093] The conventional corrugated paperboard has hygroscopicity, and after absorbing water and getting wet, the mechanical properties will be greatly reduced, on the other hand, the humid environment is easy to breed bacteria and mold, which poses a risk of harming the packaged goods and even the human body. The present application can solve the above problems by adding an antibacterial agent to the composite antibacterial coating liquid to improve the waterproof performance and impart antibacterial performance.

[0094] 1. The composite antibacterial coating is prepared by using modified epoxy resin as a film-forming material and an antibacterial agent as an active component, wherein the modified epoxy resin is obtained by modifying epoxy resin E44 with amino silicone oil, the modification of the amino silicone oil can improve the hydrophobicity of the epoxy resin E44, increase the contact angle of the prepared composite antibacterial coating with water, and enhance its waterproof ability.

[0095] 2, The antibacterial agent of the present application is a core-shell structure system with corn starch and beta-cyclodextrin as the shell, and carbon dot-silica composite particles as the core, wherein the carbon dot-silica composite particles are composed of titanium-doped carbon dots as the active antibacterial component and amino-functionalized nanoporous silica as the carrier.

[0096] 2-1, First, the present application uses cetyltrimethylammonium bromide as a template to synthesize amino-modified nanoporous silica by a hydrothermal method;

[0097] Then, using chitosan, tetracarboxyphenyl porphyrin and citric acid as main raw materials, and titanium oxalate as a doping component, a titanium-doped carbon dot with antibacterial activity is synthesized by a hydrothermal method.

[0098] Then, through shaking and blending on a shaking table, the titanium-doped carbon dots are loaded onto the amino-functionalized nanoporous silica by taking advantage of the rich pore structure of the amino-functionalized nanoporous silica, to obtain carbon dot-silica composite particles; during the loading process, the amino functional groups on the surface of the nanoporous silica can promote the connection of the titanium-doped carbon dots to the amino-functionalized nanoporous silica through electrostatic adsorption and other effects with the carboxyl functional groups on the surface of the titanium-doped carbon dots.

[0099] Finally, corn starch and beta-cyclodextrin are used as wall materials to coat the carbon dot-silica composite particles, to obtain the final antibacterial agent.

[0100] 2-2. In this antibacterial agent, titanium-doped carbon dots exhibit the ability to efficiently generate reactive oxygen species (ROS) under light irradiation. Simultaneously, these carbon dots also inherit the antibacterial properties of the precursor material chitosan. The titanium doping in the carbon dots increases the electron cloud density and active sites, thereby improving the efficiency of ROS generation under light irradiation. The titanium-doped carbon dots in this invention inherit the antibacterial mechanism of chitosan based on strong cationicity, enabling them to adsorb and bind to the negative charges on the surface of microorganisms, leading to bacterial cell wall damage. This is consistent with the antibacterial mechanism of carbon dots in the dark state (Li P, Sun L, Xue S, et al. Recent advances of carbon dots as new antimicrobial agents[J]. Smart Materials (English), 2022(002):003.). Furthermore, these carbon dots also exhibit antibacterial activity under light irradiation: under light irradiation, the carbon dots undergo excited transitions to the excited singlet state (S1), and electrons in this state can travel through intersystem crossing (ISC) to the excited triplet state (T1). Subsequently, when electrons return from the T1 state to the ground state (S0), phosphorescence (P) and reactive oxygen species (ROS) are generated. The generated ROS causes non-specific damage to bacterial cells, ultimately resulting in a bactericidal effect. Therefore, the carbon dots of this invention have antibacterial effects under both light and dark conditions, and the antibacterial effect is enhanced under light.

[0101] 2-3. In this antibacterial agent, the loading of aminated nanoporous silica endows the active component of titanium-doped carbon dots with a slow-release function, which can prolong the antibacterial effect and effectively prevent the aggregation of titanium-doped carbon dots.

[0102] 2-4. In this antibacterial agent, after further coating with a wall material, it can achieve adaptive regulation of the release rate of titanium-doped carbon dots, thereby regulating the antibacterial effect of the antibacterial active components. Specifically, the adaptive protective film formed by corn starch and β-cyclodextrin has water-soluble characteristics. When the humidity increases (such as when the surface of the composite antibacterial coating is wet or damp), the release rate of titanium-doped carbon dots will increase. Moreover, when the ambient temperature rises, the release rate of titanium-doped carbon dots will also increase, thereby enhancing the antibacterial effect of the composite antibacterial coating. When the humidity and temperature in the environment increase, it is conducive to the growth of most bacteria and molds. Therefore, the adaptive increase in antibacterial effect at this time can cope with the accelerated growth of bacteria and molds, achieving an adaptive regulation effect.

[0103] 2-5. In this antibacterial agent, in addition to serving as a carrier, the amino-modified nanoporous silica, with its nanoparticle structure, can also improve the surface roughness of the composite antibacterial coating and increase the contact angle between the surface and water, thereby enhancing the waterproof performance of the composite antibacterial coating.

[0104] II. Main role of the barrier-enhancing coating:

[0105] (1) In the present application, ethylenediamine is used to modify the pretreated graphene oxide by condensation agent method, and then blended with polyvinyl alcohol to prepare a barrier-enhancing coating liquid. Sorbitol as a plasticizer can improve the mechanical properties of the coating. With the excellent mechanical properties of graphene oxide, the addition of modified graphene oxide can also improve the mechanical properties of the coating, and finally the mechanical strength of the prepared composite corrugated paperboard can be improved.

[0106] (2) On the other hand, the addition of modified graphene oxide can form a layered stacking structure in the prepared coating. This structure prolongs the penetration path of small molecules and can enhance the barrier properties, so that the barrier-enhancing coating has good barrier ability to water, oxygen and the like, thereby reducing the erosion and damage of water, oxygen and the like to the internal corrugated paperboard substrate and improving the service life of the corrugated paperboard.

[0107] (3) In the present application, the composite antibacterial coating provides antibacterial effect by producing active oxygen and the like, but if the active oxygen enters the corrugated paperboard substrate, it will cause cellulose decomposition of the corrugated paperboard through oxidation and damage the mechanical strength of the corrugated paperboard, causing negative effects. By setting the barrier-enhancing coating, the above negative effects caused by the composite antibacterial coating can be overcome, and the active oxygen and other substances can be prevented from entering the corrugated paperboard substrate, while the waterproof performance of the corrugated paperboard can be further improved. Therefore, by combining the barrier-enhancing coating with the composite antibacterial coating, the corrugated paperboard can be endowed with excellent antibacterial and waterproof properties, the mechanical strength can be improved, and the service life can be guaranteed.

[0108] The above is the overall concept of the present application, and the following provides detailed examples and comparative examples based thereon to further illustrate the present application.

[0109] The main raw material sources in the following examples and comparative examples are described as follows:

[0110] Graphene oxide, single-layer sheet diameter 100-500 nm, Beijing Beikexin Material Technology Co., Ltd.;

[0111] Polyvinyl alcohol, PVA1799, Jiangsu Lein Environmental Protection Technology Co., Ltd.;

[0112] Chitosan, degree of deacetylation 91.8%, Shanghai Quanyan Biological Technology Co., Ltd.;

[0113] Tetracarboxyphenyl porphyrin (TCPP), cas:14609-54-2, Xi'an Qiyue Biological Technology Co., Ltd.;

[0114] Beta-cyclodextrin, Shanghai Kaisai Chemical Co., Ltd.;

[0115] Epoxy resin E44, brand: Baling Petrochemical, Haigong Chemical Technology Co., Ltd.

[0116] Amino silicone oil, Jiangsu Runfeng Synthetic Technology Co., Ltd.

[0117] 2-lauric acid-2-butyl tin (dibutyl tin dilaurate), Jiangsu Haolong Chemical Co., Ltd.

[0118] OP-10, dodecyl phenol polyoxyethylene ether, Errike (Shandong) Chemical Group Co., Ltd.

[0119] In the following examples and comparative examples, a corrugated paperboard substrate prepared by the present application is used, which comprises, from outside to inside, a face paper layer, a corrugated paper core layer, and an inner paper layer. The face paper layer, the corrugated paper core layer, and the inner paper layer are prepared from the same raw materials, which are prepared from the following components by weight parts:

[0120] Lignin fiber 65 parts;

[0121] Corn starch 13 parts;

[0122] Oxidized starch 12 parts

[0123] Corn straw powder 28 parts;

[0124] Polyvinyl alcohol 8.5 parts;

[0125] Polyacrylamide 6 parts;

[0126] Carboxymethyl cellulose 4.5 parts

[0127] Water 220 parts.

[0128] The preparation method is as follows:

[0129] 1) The lignin fiber, corn straw powder, oxidized starch, and corn straw powder are added to water, stirred uniformly, and then crushed, passed through a 100 mesh sieve, and then polyvinyl alcohol, polyacrylamide, and carboxymethyl cellulose are added. The pulp is beaten at 200 rpm and 70°C for 30 min, and then allowed to stand for 2 h to obtain a paper pulp solution;

[0130] 2) The paper pulp solution is dried and formed by papermaking to prepare the face paper layer and the inner paper layer. The paper pulp solution is papered to prepare corrugated base paper, and then corrugated and formed to prepare the corrugated paper core layer;

[0131] 3) The face paper layer, the corrugated paper core layer, and the inner paper layer are sequentially bonded by an adhesive (white latex, Dongguan Sanji Adhesive Technology Co., Ltd., model 925A, viscosity 9500 Mpa.s), and then compacted by a flattening roller (0.3 MPa pressure) and dried at 70°C for 4 h.

[0132] Example 1

[0133] A high-performance corrugated carton with waterproof and antibacterial functions, the preparation process of which comprises the following steps:

[0134] S1, providing a corrugated paperboard substrate;

[0135] S2, coating a barrier-enhancing coating liquid on the inner and outer surfaces of the corrugated paperboard substrate respectively, drying at 65 DEG C for 30 min to form a barrier-enhancing coating layer with a thickness of 0.2 mm;

[0136] S3, coating a composite antibacterial coating liquid on the surface of the barrier-enhancing coating layer, curing at 70 DEG C for 5 h to form a composite antibacterial coating layer with a thickness of 0.5 mm, thereby obtaining a composite corrugated paperboard;

[0137] S4, using the composite corrugated paperboard to make a high-performance corrugated carton with waterproof and antibacterial functions through die cutting, scoring and nailing.

[0138] In this embodiment, the barrier-enhancing coating liquid is prepared by the following method:

[0139] S2-1, 5 g of graphene oxide is added into a mixed acid composed of 50 mL of H2O2 with a concentration of 10% and 150 mL of concentrated sulfuric acid with a concentration of 95%, heated to reflux at 80 DEG C for 6 h, filtered, the solid product is washed to neutral with deionized water, and vacuum dried at 70 DEG C until constant weight, thereby obtaining pretreated graphene oxide;

[0140] S2-2, 0.3 g of the treated graphene oxide is added into 450 mL of dimethylacetamide DMF, ultrasonically dispersed for 2 h, then 35 g of ethylenediamine and 6 g of dicyclohexylcarbodiimide are added, ultrasonically dispersed for 10 min, then sealed and reacted at 135 DEG C for 48 h, after the reaction is completed, 100 mL of ethanol is added to the product, left to stand for 12 h, the supernatant is discarded, the lower layer precipitate is filtered, the solid product is washed with deionized water and ethanol in turn, and vacuum dried at 90 DEG C for 12 h, thereby obtaining modified graphene oxide.

[0141] S2-2, 1 g of the modified graphene oxide is added into 50 mL of deionized water, ultrasonically dispersed for 45 min, thereby obtaining a modified graphene oxide dispersion liquid;

[0142] S2-2, 5 g of polyvinyl alcohol, 0.8 g of sorbitol and 0.5 g of Tween 80 are added into 70 mL of deionized water, stirred at 80 DEG C for 10 min, then the modified graphene oxide dispersion liquid is added under stirring, ultrasonically dispersed for 60 min, thereby obtaining the barrier-enhancing coating liquid.

[0143] In this embodiment, the composite antibacterial coating liquid comprises the following raw material components by weight: 100 parts of modified epoxy resin emulsion, 12 parts of antibacterial agent, 23 parts of isofluroclone diamine and 85 parts of toluene. The composite antibacterial coating liquid is prepared by the following method:

[0144] 1) Divide the toluene into two parts, add the antibacterial agent to the first part of toluene, ultrasonic dispersion for 15 min to obtain an antibacterial agent dispersion liquid;

[0145] 2) Add the modified epoxy resin emulsion to the second part of toluene, stir for 10 min, add the antibacterial agent dispersion liquid under stirring, stir for 20 min, then add isorone diamine, continue to stir for 5 min to obtain an antibacterial coating liquid.

[0146] The antibacterial agent is prepared by the following method:

[0147] S3-1, preparation of aminated nanoporous silica:

[0148] S3-1-1, take 6 mL of ethanol, 0.09 g of hexadecyl trimethyl ammonium bromide, add to 40 mL of deionized water, stir for 15 min, then add 2 mL of triethanolamine dropwise, stir for 15 min, heat to 65℃, add a mixture of 3 mL of tetraethyl orthosilicate and 0.3 mL of aminopropyl methyldiethoxysilane (APTS) dropwise under stirring at 2000 rpm, maintain the current temperature, stir for 2 h at 1000 rpm;

[0149] S3-1-2, transfer the product obtained in step S3-1-1 to a reaction kettle, react at 120℃ for 48 h, cool to room temperature, centrifugal filtration, add the solid product to a mixed washing liquid composed of 30 mL of hydrochloric acid with a concentration of 5 wt% and 200 mL of ethanol, ultrasonic for 30 min, filter, wash the solid product with ethanol for 3 times, dry at 65℃ until constant weight to obtain aminated nanoporous silica.

[0150] S3-2, preparation of titanium-doped carbon dots:

[0151] S3-2-1, take 1.2 g of chitosan, add to 75 mL of 1.5% acetic acid aqueous solution, stir for 5 min to obtain a mixed liquid 1;

[0152] S3-2-2, take 0.593 g of tetracarboxyphenyl porphyrin, 0.768 g of citric acid, 0.468 g of titanium oxalate, add to 100 mL of deionized water, stir for 10 min to obtain a mixed liquid 2;

[0153] S3-2-3, add the mixed liquid 1 to the mixed liquid 2, stir for 20 min to obtain a precursor liquid, transfer the precursor liquid to a reaction kettle with a polytetrafluoroethylene liner, react at 190℃ for 10 h, after the reaction is completed, cool to room temperature, filter the product with a filter membrane with a pore size of 0.22 μm, dialyze the filtrate in a dialysis bag with a molecular weight cut-off of 1000D in deionized water for 48 h, remove the dialysate in the dialysis bag, rotary evaporate and freeze-dry to obtain titanium-doped carbon dots.

[0154] S3-3, taking amino-modified nanoporous silica as a carrier, titanium-doped carbon dots as an active antibacterial component, loading titanium-doped carbon dots on the amino-modified nanoporous silica to obtain carbon dot-silica composite particles:

[0155] S3-3-1, take 1g of amino-modified nanoporous silica and add it to 50mL of deionized water, ultrasonic dispersion for 15min to obtain a silica dispersion;

[0156] S3-3-2, take 0.45g of titanium-doped carbon dots and add it to 50mL of deionized water, ultrasonic dispersion for 15min to obtain a carbon dot dispersion;

[0157] S3-3-3, under stirring, add the carbon dot dispersion to the silica dispersion, shake at 60℃, 100rpm for 24h, filter, and vacuum dry the solid product at 70℃ for 12h to obtain carbon dot-silica composite particles.

[0158] S3-4, coating a self-adaptive protective film on the surface of the carbon dot-silica composite particles:

[0159] Take 0.3g of corn starch and 0.7g of β-cyclodextrin and add them to 100mL of distilled water, ultrasonic dispersion for 15min, heating in a boiling water bath under stirring for 60min, keep stirring, add 0.5g of carbon dot-silica composite particles, continue stirring for 1h after cooling to 65℃, stand at 5℃ for 24h, suction filtration, wash the solid product with ethanol, vacuum freeze-drying to obtain an antibacterial agent.

[0160] The modified epoxy resin emulsion is prepared by the following method:

[0161] Take 5g of amino silicone oil, 0.75g of OP-10 and add them to 20mL of toluene, stir at 65℃, 2000rpm for 45min, then add 6g of epoxy resin E44, 0.1g of 2-lauryl acid-2-butyl tin, heat under reflux at 78℃ for 5h to obtain a modified epoxy resin emulsion.

[0162] Example 2

[0163] A high-performance corrugated carton with waterproof and antibacterial functions, the preparation process of which comprises the following steps:

[0164] S1, providing a corrugated paperboard substrate;

[0165] S2, coating a barrier-enhancing coating liquid on the inner and outer surfaces of the corrugated paperboard substrate respectively, drying at 65℃ for 30min to form a barrier-enhancing coating layer with a thickness of 0.2mm;

[0166] S3, coating the composite antibacterial coating liquid on the surface of the barrier-enhanced coating layer, and curing at 70°C for 5h to form a composite antibacterial coating layer with a thickness of 0.5mm, thereby obtaining a composite corrugated paperboard;

[0167] S4, using the composite corrugated paperboard to make a high-performance corrugated paper box with waterproof and antibacterial functions through die cutting, scoring and nailing.

[0168] In this embodiment, the barrier-enhanced coating liquid is prepared by the following method:

[0169] S2-1, 5g of graphene oxide was taken and added to a mixed acid composed of 50mL of 10% H2O2 and 150mL of 95% concentrated sulfuric acid, heated to reflux at 80°C for 6h, filtered, and the solid product was washed with deionized water until neutral, and vacuum dried at 70°C to constant weight to obtain pretreated graphene oxide;

[0170] S2-2, 0.3g of the treated graphene oxide was added to 450mL of dimethylacetamide DMF, ultrasonically dispersed for 2h, then 35g of ethylenediamine and 6g of dicyclohexyl carbodiimide were added, ultrasonically dispersed for 10min, then sealed and reacted at 135°C for 48h, then 100mL of ethanol was added to the product, and after standing for 12h, the supernatant was discarded, and the lower layer was filtered, and the solid product was washed with deionized water and ethanol, and vacuum dried at 90°C for 12h to obtain modified graphene oxide.

[0171] S2-2, 0.85g of modified graphene oxide was added to 50mL of deionized water, and ultrasonically dispersed for 45min to obtain a modified graphene oxide dispersion;

[0172] S2-2, 5g of polyvinyl alcohol, 0.8g of sorbitol, and 0.5g of Tween 80 were added to 70mL of deionized water, stirred at 80°C for 10min, then the modified graphene oxide dispersion was added under stirring, and ultrasonically dispersed for 60min to obtain a barrier-enhanced coating liquid.

[0173] In this embodiment, the composite antibacterial coating liquid comprises the following raw material components by weight: 100 parts of modified epoxy resin emulsion, 12 parts of antibacterial agent, 25 parts of isoflurone diamine, and 82 parts of toluene. The preparation method of the composite antibacterial coating liquid is the same as that of Example 1.

[0174] Example 3

[0175] A high-performance corrugated paper box with waterproof and antibacterial functions, the preparation process thereof comprises the following steps:

[0176] S1, providing a corrugated paperboard substrate;

[0177] S2, coating barrier-enhancing coating liquid on the inner and outer surfaces of the corrugated paperboard substrate respectively, drying at 65℃ for 30 min, forming a barrier-enhancing coating layer with a thickness of 0.2 mm;

[0178] S3, coating composite antibacterial coating liquid on the surface of the barrier-enhancing coating layer, curing at 70℃ for 5 h, forming a composite antibacterial coating layer with a thickness of 0.5 mm, obtaining a composite corrugated paperboard;

[0179] S4, using the composite corrugated paperboard to make high-performance corrugated paper boxes with waterproof and antibacterial functions through die cutting, scoring and nailing.

[0180] In this embodiment, the barrier-enhancing coating liquid is prepared by the following method:

[0181] S2-1, 5 g of graphene oxide is added to a mixed acid composed of 50 mL of 10% H2O2 and 150 mL of 95% concentrated sulfuric acid, heated to reflux at 80℃ for 6 h, filtered, the solid product is washed to neutral with deionized water, and vacuum dried at 70℃ to constant weight to obtain pretreated graphene oxide;

[0182] S2-2, 0.35 g of treated graphene oxide is added to 450 mL of dimethylacetamide DMF, ultrasonic dispersion for 2 h, then 38 g of ethylenediamine and 6.5 g of dicyclohexyl carbodiimide are added, ultrasonic dispersion for 10 min, then sealed and reacted at 135℃ for 48 h, after the reaction is completed, 100 mL of ethanol is added to the product, and it is left to stand for 12 h, the supernatant is discarded, the lower layer precipitate is filtered, and the solid product is washed with deionized water and ethanol in turn, and vacuum dried at 90℃ for 12 h to obtain modified graphene oxide.

[0183] S2-2, 1.2 g of modified graphene oxide is added to 50 mL of deionized water, ultrasonic dispersion for 45 min to obtain a modified graphene oxide dispersion;

[0184] S2-2, 5 g of polyvinyl alcohol, 0.8 g of sorbitol and 0.5 g of Tween 80 are added to 70 mL of deionized water, stirred at 80℃ for 10 min, then the modified graphene oxide dispersion is added under stirring, ultrasonic dispersion for 60 min to obtain a barrier-enhancing coating liquid.

[0185] In this embodiment, the composite antibacterial coating liquid comprises the following raw material components by weight: modified epoxy resin emulsion 100 parts, antibacterial agent 12 parts, isoflurone diamine 20 parts, toluene 80 parts. The composite antibacterial coating liquid is prepared by the following method:

[0186] 1) The toluene is divided into two parts, the antibacterial agent is added to the first part of toluene, ultrasonic dispersion for 15 min to obtain an antibacterial agent dispersion;

[0187] 2) Add the modified epoxy resin emulsion into the second part of toluene, stir for 10 min, and then add the antibacterial agent dispersion liquid under stirring, stir for 20 min, and then add isorolone diamine, continue to stir for 5 min, to obtain an antibacterial coating liquid.

[0188] The antibacterial agent is prepared by the following method:

[0189] S3-1, preparation of aminated nanoporous silica:

[0190] S3-1-1, take 6 mL of ethanol, 0.09 g of hexadecyl trimethyl ammonium bromide, and add them to 40 mL of deionized water, stir for 15 min, then drop 2 mL of triethanolamine, stir for 15 min, and then heat to 65℃, drop a mixture of 3 mL of tetraethyl orthosilicate and 0.3 mL of aminopropyl methyl diethoxysilane (APTS) under stirring at 2000 rpm, maintain the current temperature, and stir for 2 h at 1000 rpm;

[0191] S3-1-2, transfer the product obtained in step S3-1-1 to a reaction kettle, react at 120℃ for 48 h, cool to room temperature, centrifugal filtration, add the solid product to a mixed washing liquid composed of 30 mL of hydrochloric acid with a concentration of 5 wt% and 200 mL of ethanol, ultrasonic for 30 min, filter, and then wash the solid product with ethanol for 3 times, and dry at 65℃ until constant weight, to obtain aminated nanoporous silica.

[0192] S3-2, preparation of titanium-doped carbon dots:

[0193] S3-2-1, take 1.2 g of chitosan, add it to 75 mL of 1.5% acetic acid aqueous solution, stir for 5 min, to obtain a mixed liquid 1;

[0194] S3-2-2, take 0.593 g of tetracarboxyphenyl porphyrin, 0.768 g of citric acid, and 0.468 g of titanium oxalate, add them to 100 mL of deionized water, stir for 10 min, to obtain a mixed liquid 2;

[0195] S3-2-3, add the mixed liquid 1 to the mixed liquid 2, stir for 20 min, to obtain a precursor liquid, transfer the precursor liquid to a reaction kettle with a polytetrafluoroethylene liner, react at 190℃ for 10 h, cool to room temperature after the reaction is completed, filter the product with a filter membrane with a pore size of 0.22 μm, dialyze the filtrate in a dialysis bag with a molecular weight cut-off of 1000D in deionized water for 48 h, remove the dialysate in the dialysis bag, rotary evaporate, and then freeze-dry, to obtain titanium-doped carbon dots.

[0196] S3-3, use aminated nanoporous silica as a carrier and titanium-doped carbon dots as an active antibacterial component, load the titanium-doped carbon dots on the aminated nanoporous silica, to obtain carbon dot-silica composite particles:

[0197] S3-3-1, 1 g of aminosilica was taken and added to 50 mL of deionized water, and ultrasonic dispersion was performed for 15 min to obtain a silica dispersion liquid;

[0198] S3-3-2, 0.50 g of titanium-doped carbon dots was taken and added to 50 mL of deionized water, and ultrasonic dispersion was performed for 15 min to obtain a carbon dot dispersion liquid;

[0199] S3-3-3, the carbon dot dispersion liquid was added to the silica dispersion liquid under stirring, and the mixture was shaken on a shaking table at 60°C and 100 rpm for 24 h, and then filtration was performed, and the solid product was vacuum dried at 70°C for 12 h to obtain carbon dot-silica composite particles.

[0200] S3-4, a self-adaptive protective film was coated on the surface of the carbon dot-silica composite particles:

[0201] 0.3 g of corn starch and 0.7 g of β-cyclodextrin were taken and added to 100 mL of distilled water, and ultrasonic dispersion was performed for 15 min, and then the mixture was heated in a boiling water bath under stirring for 60 min, and then 0.5 g of the carbon dot-silica composite particles was added, and the mixture was continuously stirred at 65°C for 1 h, and then the mixture was allowed to stand at 5°C for 24 h, and then filtration was performed, and the solid product was washed with ethanol, and then vacuum freeze-drying was performed to obtain an antibacterial agent.

[0202] The modified epoxy resin emulsion was prepared by the following method:

[0203] 5 g of amino silicone oil, 0.75 g of OP-10, and 20 mL of toluene were taken, and stirring was performed at 65°C and 2000 rpm for 45 min, and then 6 g of epoxy resin E44, 0.1 g of 2-lauryl acid-2-butyl tin was added, and the mixture was heated and refluxed at 78°C for 5 h to obtain a modified epoxy resin emulsion.

[0204] Comparative Example 1

[0205] This example is basically the same as Example 1, except that no antibacterial agent was added to the composite antibacterial coating solution in this example.

[0206] Comparative Example 2

[0207] This example is basically the same as Example 1, except that:

[0208] The antibacterial agent in this example was prepared by the following method:

[0209] S3-1, aminosilica was prepared, and the specific method was the same as that in Example 1;

[0210] S3-2, carbon dots were prepared:

[0211] S3-2-1, 1.2 g of chitosan was taken and added to 75 mL of 1.5% acetic acid aqueous solution, stirred for 5 min to obtain a mixed solution 1;

[0212] S3-2-2, 0.593 g of tetracarboxyphenyl porphyrin and 0.768 g of citric acid were taken and added to 100 mL of deionized water, stirred for 10 min to obtain a mixed solution 2;

[0213] S3-2-3, the mixed solution 1 was added to the mixed solution 2, stirred for 20 min to obtain a precursor solution, the precursor solution was transferred to a polytetrafluoroethylene lined reaction kettle, reacted at 190℃ for 10 h, after the reaction was completed, it was cooled to room temperature, the product was filtered with a 0.22 μm filter membrane, the filtrate was dialyzed in deionized water for 48 h with a dialysis bag with a molecular weight cut-off of 1000D, the dialysate in the dialysis bag was removed, rotary evaporation and freeze-drying were carried out to obtain carbon dots.

[0214] S3-3, taking amino-functionalized nanoporous silica as a carrier and carbon dots as an active antibacterial component, the carbon dots were loaded on the amino-functionalized nanoporous silica to obtain carbon dot-silica composite particles:

[0215] S3-3-1, 1 g of amino-functionalized nanoporous silica was taken and added to 50 mL of deionized water, ultrasonically dispersed for 15 min to obtain a silica dispersion;

[0216] S3-3-2, 0.45 g of carbon dots was taken and added to 50 mL of deionized water, ultrasonically dispersed for 15 min to obtain a carbon dot dispersion;

[0217] S3-3-3, the carbon dot dispersion was added to the silica dispersion under stirring, and the shaking table was shaken at 60℃ and 100 rpm for 24 h, then filtered, and the solid product was vacuum dried at 70℃ for 12 h to obtain carbon dot-silica composite particles.

[0218] S3-4, a self-adaptive protective film was coated on the surface of the carbon dot-silica composite particles, and the specific method was the same as that of Example 1.

[0219] Comparative Example 3

[0220] This example is basically the same as Example 1, except that:

[0221] In this example, an epoxy resin emulsion is used instead of the modified epoxy resin emulsion in Example 1, and the epoxy resin emulsion is prepared by the following method:

[0222] 6 g of epoxy resin E44 was taken and added to 20 mL of toluene, stirred at 65℃ and 2000 rpm for 45 min to obtain an epoxy resin emulsion.

[0223] Comparative Example 4

[0224] This example is basically the same as Example 1, the only difference is that:

[0225] The barrier-enhancing coating solution in this example is prepared by the following method:

[0226] Take 5g polyvinyl alcohol, 0.8g sorbitol, 0.5g Tween 80 into 70mL deionized water, stir at 80℃ for 10min, get the barrier-enhancing coating solution.

[0227] Performance test

[0228] 1. Active oxygen release performance test of the antibacterial agent:

[0229] Take 1g of the antibacterial agent prepared in Example 1 and evenly spread it on a glass surface dish, place it in a glass desiccator, control the temperature and humidity in the desiccator, ventilate every 5h for 5min, irradiate with a daylight lamp every 5h for 1h, and take a sample every 12h for measurement. The method is as follows: Put the antibacterial agent into a filter bag, then immerse the filter bag in 500mL of anhydrous ethanol, and ultrasonically soak for 5min. Take it out and evenly spread it again on a glass surface dish, and continue to place it in a glass desiccator. For the anhydrous ethanol after soaking (i.e. the fluorescence test solution), determine its fluorescence intensity at 488nm excitation wavelength and 525nm emission wavelength by using a reactive oxygen species assay kit (Nanjing Fengmo Biological Technology Co., Ltd.). After testing, the anhydrous ethanol is sealed and stored for subsequent soaking and fluorescence detection.

[0230] Detect the fluorescence intensity of the fluorescence test solution at different times to determine the cumulative release amount of active oxygen at different times. The higher the fluorescence intensity, the higher the active oxygen content.

[0231] The test results are shown in Figure 1 and Figure 2 :

[0232] According to Figure 1 , which shows the active oxygen release amount test results at different relative humidities at 25℃, it can be seen that the active oxygen release amount increases with the increase of humidity;

[0233] According to Figure 2 , which shows the active oxygen release amount test results at different temperatures at a relative humidity of 70%, it can be seen that the active oxygen release amount increases with the increase of temperature.

[0234] The test results of Figure 1 and Figure 2 show that the antibacterial agent of the present application can produce and release active oxygen under light, and its release amount increases with the increase of temperature and humidity, which has a self-regulating property.

[0235] 2. Refer to Figure 3 The infrared absorption spectrum of the titanium-doped carbon dots prepared in Example 1 illustrates the successful synthesis of the titanium-doped carbon dots.

[0236] 3. Bacteriostatic performance test

[0237] Test method: Using the bacteriostatic ring method, Escherichia coli was used as the test strain, the composite corrugated board was cut into a circular paper sample with a diameter of 10 mm, the Escherichia coli was inoculated into a nutrient agar culture medium, and after uniform coating, the circular paper sample was placed at the center of the culture medium, and incubated at 37°C for 48h. The diameter of the bacteriostatic ring was measured by cross method.

[0238] (1) Using the method of Example 1, adjust the addition amount of antibacterial agent in the composite antibacterial coating liquid, and the rest of the conditions remain unchanged, several composite corrugated boards are prepared, and the above method is used for testing, and light group and no light group are set. The light group is irradiated by fluorescent lamp for 1h every 5h, and the no light group is always light-protected.

[0239] The test results are shown in Figure 4 and Table 1 below:

[0240] Table 1

[0241]

[0242] From the test results, it can be seen that the composite corrugated board prepared in Example 1 has bacteriostatic performance under light and dark conditions, and the bacteriostatic performance is stronger under light, which is mainly due to the active oxygen produced by the antibacterial agent under light. When the corrugated paper box is used, the composite antibacterial coating on the outer surface can usually receive sunlight in many scenarios, and it is also more likely to be wet or damp, and the risk of bacterial growth is greater. Because of the greater chance of receiving sunlight, it will show stronger bacteriostatic performance, thus exactly adapting to its greater risk of bacterial growth; the composite antibacterial coating on the inner surface usually cannot receive sunlight, and mainly realizes bacteriostasis through the bacteriostatic mechanism of the antibacterial agent in the dark state, and the bacteriostatic performance is relatively weak, which can also match its smaller risk of being damp.

[0243] (2) Test the bacteriostatic performance of the composite corrugated boards prepared in Examples 2-3 and Comparative Examples 1-5 according to the above method, and all according to the same conditions as the light group in (1).

[0244] 4. The water contact angle of the composite antibacterial coating layer of the composite corrugated board prepared in the examples and comparative examples was measured by using a contact angle tester (Germany dataphysics OCA25-HTV1800).

[0245] 5. Burst strength, the composite corrugated paperboard prepared in the examples and comparative examples was detected according to the standard "GB / T6544-2008".

[0246] 6. Edge crush strength, the composite corrugated paperboard prepared in the examples and comparative examples was detected according to the standard "GB / T6544-2008".

[0247] The test results are shown in Table 2:

[0248] Table 2

[0249] Bacteriostatic zone diameter / mm Water contact angle (°) Breaking strength (kPa) Edge compression strength (kN / m) Example 1 35 107.2 1241 6.1 Example 2 35 107.8 1227 6.0 Example 3 33 106.5 1237 6.1 Comparative Example 1 0 85.1 1179 5.9 Comparative Example 2 30 106.8 1243 6.1 Comparative Example 3 34 100.5 1226 6.0 Comparative Example 4 35 107.4 1014 5.5

[0250] It can be seen from the test results that the composite corrugated paperboard prepared in examples 1-3 has excellent antibacterial performance and good waterproof performance, and can also ensure high mechanical strength; the composite antibacterial coating liquid in comparative example 1 does not add an antibacterial agent, resulting in a significant decrease in antibacterial performance and waterproof performance; the decrease in antibacterial performance in comparative example 2 is due to the fact that titanium is not doped in the carbon dots, resulting in a decrease in the generation efficiency of active oxygen; no modified epoxy resin is used in comparative example 3, resulting in a decrease in hydrophobicity; no modified graphene oxide is added in the barrier-enhancing coating liquid in comparative example 4, resulting in a decrease in mechanical strength.

[0251] Although the embodiments of the present application have been disclosed as above, it is not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to specific details, but falls within the general concept defined by the claims and the equivalent scope.

Claims

1. A process for preparing a high-performance corrugated paper box with waterproof and antibacterial functions, characterized in that, The method comprises the following steps: S1, providing a corrugated paperboard substrate; S2, coating a barrier-enhancing coating liquid on the inner and outer surfaces of the corrugated paperboard substrate respectively, and forming a barrier-enhancing coating layer after curing; S3, coating a composite antibacterial coating liquid on the surface of the barrier-enhancing coating layer, and forming a composite antibacterial coating layer after curing, to obtain a composite corrugated paperboard; S4, using the composite corrugated paperboard to manufacture a high-performance corrugated paper box with waterproof and antibacterial functions; The barrier-enhancing coating liquid is prepared by the following method: S2-1, 2.5-10 g of graphene oxide is added into a mixed acid composed of 25-100 mL of H2O2 with a concentration of 10% and 50-300 mL of concentrated sulfuric acid with a concentration of 95 wt%, heated and refluxed at 70-85°C for 4-12 h, filtered, the solid product is washed with deionized water until neutral, and vacuum dried at 60-90°C until constant weight, to obtain pretreated graphene oxide; S2-2, 0.15-0.6 g of the pretreated graphene oxide is added into 225-900 mL of dimethylacetamide, ultrasonically dispersed for 1-4 h, then 17.5-70 g of ethylenediamine and 3-6 g of dicyclohexylcarbonylimide are added, ultrasonically dispersed for 5-30 min, then sealed and reacted at 125-140°C for 24-72 h, 50-200 mL of ethanol is added to the product after the reaction is completed, left to stand for 6-24 h, the supernatant is discarded, the lower layer of the precipitate is filtered, and the solid product is washed with deionized water and ethanol in sequence, and vacuum dried at 90-100°C for 6-24 h, to obtain modified graphene oxide; S2-3, 0.5-2 g of the modified graphene oxide is added into 25-100 mL of deionized water, and ultrasonically dispersed for 30-90 min, to obtain a modified graphene oxide dispersion liquid; S2-4, 2.5-10 g of polyvinyl alcohol, 0.4-1.6 g of sorbitol and 0.25-1 g of Tween 80 are added into 50-150 mL of deionized water, stirred at 70-85°C for 5-20 min, then the modified graphene oxide dispersion liquid is added under stirring, ultrasonically dispersed for 30-90 min, to obtain the barrier-enhancing coating liquid; The composite antibacterial coating liquid comprises the following raw material components by weight: 80-120 parts of modified epoxy resin emulsion, 8-17 parts of antibacterial agent, 15-28 parts of curing agent, and 65-105 parts of organic solvent; The modified epoxy resin emulsion is prepared by the following method: 2.5-10 g of amino silicone oil and 0.35-1.5 g of OP-10 are added into 20 mL of toluene, stirred at 60-70°C and 1000-4000 rpm for 30-90 min, then 3-12 g of epoxy resin E44 and 0.05-0.2 g of 2-lauryl acid-2-butyl tin are added, heated and refluxed at 72-80°C for 3-8 h, to obtain the modified epoxy resin emulsion; The antibacterial agent is prepared by the following method: S3-1, aminoized nano-porous silicon dioxide is prepared; S3-1-1, 3-12 mL of ethanol, 0.03-0.18 g of cetyltrimethylammonium bromide was added to 20-80 mL of deionized water, stirred for 5-30 min, then 1-4 mL of triethanolamine was added dropwise, stirred for 5-30 min, heated to 55-70℃, a mixture of 1.5-6 mL of tetraethyl orthosilicate and 0.15-0.6 mL of aminopropylmethyldiethoxysilane was added dropwise under stirring at 1000-4000 rpm, the current temperature was maintained, and the reaction was carried out under stirring at 500-1000 rpm for 2 h; S3-1-2, the product obtained in step S3-1-1 was transferred to a reaction kettle, and reacted at 110-130℃ for 24-72 h, cooled to room temperature, centrifuged and filtered, the solid product was added to a mixed washing solution composed of 15-60 mL of 5wt% hydrochloric acid and 100-400 mL of ethanol, ultrasonicated for 15-60 min, filtered, and the solid product was washed with ethanol, and dried at 50-80℃ until the weight was constant to obtain aminated nanoporous silica; S3-2, titanium-doped carbon dots were synthesized by a hydrothermal method using chitosan, tetracarboxyphenyl porphyrin and citric acid as main raw materials, and titanium oxalate as a doping component; S3-3, the aminated nanoporous silica was used as a carrier, and the titanium-doped carbon dots were used as an active antibacterial component, and the titanium-doped carbon dots were loaded on the aminated nanoporous silica to obtain carbon dot-silica composite particles; S3-4, corn starch and β-cyclodextrin were used as wall materials to coat the carbon dot-silica composite particles to obtain an antibacterial agent.

2. The process for preparing high-performance corrugated paper box with waterproof and antibacterial functions according to claim 1, characterized in that, Step S3-2 is specifically: S3-2-1, 0.6-2.4 g of chitosan was added to 50-150 mL of 1-3wt% acetic acid aqueous solution, and stirred for 3-10 min to obtain a mixed solution 1; S3-2-2, 0.29-1.186 g of tetracarboxyphenyl porphyrin, 0.384-1.536 g of citric acid and 0.234-0.936 g of titanium oxalate were added to 50-200 mL of deionized water, and stirred for 5-20 min to obtain a mixed solution 2; S3-2-3, the mixed solution 1 was added to the mixed solution 2, and stirred for 10-40 min to obtain a precursor solution, and the precursor solution was transferred to a reaction kettle lined with polytetrafluoroethylene, and reacted at 170-210℃ for 6-24 h, and then cooled to room temperature, and the product was filtered with a 0.22 μm filter membrane, and the filtrate was dialyzed in deionized water for 48 h with a dialysis bag with a molecular weight cut-off of 1000D, and the dialysate in the dialysis bag was taken, rotary evaporated and freeze-dried to obtain titanium-doped carbon dots.

3. The process for preparing high-performance corrugated paper boxes with waterproof and antibacterial functions according to claim 2, characterized in that, Step S3-3 is specifically: S3-3-1, 0.5-2 g of aminated nanoporous silica was added to 25-100 mL of deionized water, and ultrasonically dispersed for 5-30 min to obtain a silica dispersion; S3-3-2, 0.225-0.9 g of titanium-doped carbon dots was added to 25-100 mL of deionized water, and ultrasonically dispersed for 5-30 min to obtain a carbon dot dispersion; S3-3-3, under stirring, the carbon dots dispersion liquid is added into the silica dispersion liquid, and the mixture is shaken at 50-70℃ and 80-200rpm for 12-48h, then filtered, and the solid product is vacuum dried at 60-80℃ for 6-24h to obtain carbon dots-silica composite particles.

4. The process for preparing high-performance corrugated paper boxes with waterproof and antibacterial functions according to claim 3, characterized in that, The step S3-4 is specifically as follows: 0.15-0.6g of corn starch and 0.35-1.4g of β-cyclodextrin are added into 50-200mL of distilled water, and ultrasonic dispersed for 10-30min, then heated in a boiling water bath under stirring for 30-90min, and 0.25-1g of carbon dots-silica composite particles is added, and the mixture is continuously stirred at 60-70℃ for 0.5-2h, and then left to stand at 2-10℃ for 12-48h, and then filtered, and the solid product is washed with ethanol and vacuum freeze-dried to obtain the antibacterial agent.

5. The process for preparing high performance corrugated paper box with waterproof and antibacterial function according to claim 1, characterized in that, The organic solvent is toluene, and the curing agent is isophorone diamine; The composite antibacterial coating liquid is prepared by the following method: 1) the toluene is divided into two parts, the antibacterial agent is added into the first part of toluene, and ultrasonic dispersed for 5-30min to obtain an antibacterial agent dispersion liquid; 2) the modified epoxy resin emulsion is added into the second part of toluene, and stirred for 5-20min, then the antibacterial agent dispersion liquid is added under stirring, and stirred for 10-45min, then the isophorone diamine is added, and the mixture is continuously stirred for 3-10min to obtain the composite antibacterial coating liquid.

6. The process for preparing high performance corrugated paper box with waterproof and antibacterial function according to claim 1, characterized in that, The method comprises the following steps: S1, providing a corrugated paperboard substrate; S2, coating a barrier-enhancing coating liquid on the inner and outer surfaces of the corrugated paperboard substrate respectively, and baking at 50-80℃ for 15-60min to form a barrier-enhancing coating layer with a thickness of 0.1-0.5mm; S3, coating the composite antibacterial coating liquid on the surface of the barrier-enhancing coating layer, and curing at 60-80℃ for 3-8h to form a composite antibacterial coating layer with a thickness of 0.25-1mm, to obtain a composite corrugated paperboard; S4, using the composite corrugated paperboard to make the waterproof and antibacterial high-performance corrugated paper box through die cutting, scoring, and nailing / gluing.

7. A high-performance corrugated carton with waterproof and antibacterial functions, characterized in that, The waterproof and antibacterial high-performance corrugated paper box is prepared by the process of any one of claims 1-6.

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