A packaging box high adhesion printing ink and a preparation method thereof

Abstract

The application discloses a packaging box high-adhesion printing ink and a preparation method thereof, and relates to the technical field of inks. The preparation method comprises the following steps: uniformly dispersing titanium white powder in deionized water, then adding modified water-based polyurethane emulsion, continuously stirring and uniformly mixing, and then adding hydroxypropyl methyl cellulose, sodium dodecyl benzene sulfonate and polyethylene glycol in sequence and uniformly stirring to obtain the product. The water-based polyurethane emulsion is modified, the adhesion of the ink on the surface of the packaging box is improved, the comprehensive performance of the ink is enhanced, and the demand of the packaging printing industry for high-quality and environment-friendly inks is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ink, in particular to a packaging box high-adhesion printing ink and a preparation method thereof. BACKGROUND

[0002] In the field of packaging printing, water-based ink as an environmentally friendly printing material is gradually replacing traditional oil-based ink to meet the increasingly stringent environmental regulations and people's demand for green products. Water-based polyurethane ink, as an important branch of water-based ink, occupies an important position in this field due to its unique advantages.

[0003] Water-based polyurethane ink uses water-based polyurethane as a connecting material and has many advantages. The molecular chain contains polar groups such as urethane, uretonimine, ester bond, and ether bond, which have affinity for the polar groups on the surface of film substrates such as PET and PA plastic, and can form hydrogen bonds, thereby enabling the ink to exhibit good adhesion on the surface of these polar plastic substrates. At the same time, water-based polyurethane ink also has excellent yellowing resistance, which is due to the use of aliphatic polyester and aliphatic isocyanate as raw materials in the preparation process. Compared with aromatic polyurethane, it has better optical stability and the film is not prone to yellowing after film formation. In addition, water-based polyurethane ink has good affinity and wettability for pigments / dyes. The polyurethane resin prepared from polyester or polyether polyol, alicyclic diisocyanate, and diamin / diol chain extender, introduces urea bond to form polyurethane-urea resin, which helps to disperse and wet the pigments. In terms of film forming performance, the introduction of urea group into the polyurethane resin used in the ink greatly improves the cohesive strength, meeting the film forming requirements of the ink. And it has wide compatibility with organic solvents and good solvent release. Although alcohol solvents can wrap the polyurethane resin molecules as pseudo-solvents, the ink still maintains good fluidity.

[0004] For packaging box printing, high-adhesion ink is essential. During production, transportation, and storage, packaging boxes may be subjected to various friction, collision, and environmental factors. If the ink adhesion is insufficient, problems such as ink peeling and color loss may occur, which not only affects the appearance of the packaging box, but also may cause product information to be blurred, reducing product quality and market competitiveness. Therefore, developing a water-based polyurethane ink for packaging boxes that does not require complex surface treatment and has high adhesion to various packaging box substrates has become an urgent problem in the field. SUMMARY

[0005] The present application aims to provide a packaging box high adhesion printing ink and a preparation method thereof, so as to solve the technical problem of poor adhesion of the water-based polyurethane ink on the packaging box in the background art. The present application improves the adhesion of the ink on the surface of the packaging box by modifying the water-based polyurethane emulsion, enhances the comprehensive performance of the ink, and meets the demand of the packaging printing industry for high-quality and environmentally friendly ink.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A packaging box high adhesion printing ink comprises the following components by weight:

[0008] 70-80 parts of modified water-based polyurethane emulsion, 30-40 parts of titanium dioxide, 3-5 parts of hydroxypropyl methyl cellulose, 3-5 parts of sodium dodecyl benzene sulfonate, 1-3 parts of polyethylene glycol, and 60-70 parts of deionized water.

[0009] The modified water-based polyurethane emulsion is used as the core film-forming material. Through special modification treatment, the polar groups in the molecular chain of the modified water-based polyurethane emulsion form firm hydrogen bonds with the surface of the packaging box substrate, and the micro-nano structure of the composite particles enhances the mechanical anchoring effect, greatly improving the adhesion of the ink to the substrate and ensuring that the ink is not easy to fall off in the environment of friction, collision and the like. The titanium dioxide as a pigment not only provides excellent whiteness and hiding power for the ink, but also fills the gaps in the film layer and enhances the compactness and mechanical strength of the ink film. The hydroxypropyl methyl cellulose thickening agent can adjust the viscosity of the ink, ensure the leveling property and stability in the printing process, and avoid the phenomenon of missing printing or ink stacking. The sodium dodecyl benzene sulfonate wetting agent can effectively reduce the surface tension of the ink, promote the uniform spreading of the ink on the substrate surface, and further improve the adhesion uniformity. The polyethylene glycol defoaming agent can eliminate the air bubbles generated in the printing process, prevent film defects caused by air bubbles, and ensure the printing quality. The deionized water as a dispersion medium cooperates with various additives to realize system stability, and there is no volatile organic pollutant in the whole process, which meets the environmental protection requirements.

[0010] Preferably, the preparation method of the modified water-based polyurethane emulsion comprises the following steps:

[0011] S1. Hydroxyapatite is added to an epoxy silane coupling agent hydrolysate, and heated to react to obtain epoxy hydroxyapatite;

[0012] S2. Nano-cellulose is dispersed in deionized water, and then the epoxy hydroxyapatite is added and heated to react to obtain composite particles;

[0013] S3. Carboxymethyl chitosan is dissolved in a buffer solution to form a carboxymethyl chitosan solution, and then the composite particles are added and heated to react under the action of a catalyst to obtain organic composite particles;

[0014] S4, adding isophorone diisocyanate and dibutyl tin dilaurate into polybutylene adipate glycol, heating and reacting, then adding dimethylol propionic acid, continuing to react, to obtain polyurethane prepolymer;

[0015] S5, dispersing the organic compound particles in acetone, uniformly dispersing by ultrasonic, then slowly adding into the polyurethane prepolymer to react, through neutralization, emulsification, chain extension and reduced pressure distillation, to obtain modified water-based polyurethane emulsion.

[0016] The carboxymethyl chitosan molecular chain introduced in the modification process of the modified water-based polyurethane emulsion contains a large number of hydroxyl groups, which can form dense hydrogen bonding with the packaging box substrate (such as the cellulose hydroxyl group of the card paper and the polar group on the plastic surface), and the intermolecular force can strengthen the interface bonding between the ink and the substrate, thereby improving the adhesion from the chemical action level, and avoiding the ink from falling off under the working conditions such as friction and bending. The micro-nano composite structure formed by the combination of hydroxyapatite (nano scale) and nanocellulose (micro scale) can accurately match the unevenness (such as the gap between the card paper fibers) on the surface of the packaging box substrate, and realize physical and mechanical engagement through the "rivet effect". Figure 1 The SEM image of the surface of the composite particles prepared in the present application can be observed to have a rough nano structure on the surface of the nanocellulose. The nanohydroxyapatite fills the nanoscale pores of the substrate, and the microscale nanocellulose is embedded in the macroscopic gap of the substrate, and the two cooperatively build a multi-dimensional anchoring structure, which greatly improves the mechanical bonding strength between the ink and the substrate. In addition, the micro-nano structure can well fill the void defects formed in the ink, thereby increasing the contact area between the ink and the substrate, further improving the bonding force between the ink and the substrate, and improving the adhesion. The surface of the composite particles is modified by carboxymethyl chitosan, which gives it good hydrophilicity and compatibility with the polyurethane matrix, ensures uniform dispersion of the organic compound particles in the polyurethane prepolymer, and avoids agglomeration. This uniform dispersion not only fully utilizes the reinforcing effect of each particle, but also ensures the uniformity of the ink film, reduces the adhesion decay caused by local defects, and improves the stability and printing suitability of the ink. By combining the organic compound particles with the water-based polyurethane, the dispersion performance of the organic compound particles in the water-based polyurethane film-forming material can be greatly improved, thereby helping to improve the comprehensive performance of the ink.

[0017] Preferably, in step S1, the particle size of the hydroxyapatite is 5-10 nm.

[0018] Preferably, in step S2, the length of the nanocellulose is 1-5 μm, and the diameter is 200-500 nm.

[0019] Preferably, in step S2, the mass ratio of nanocellulose to epoxidized hydroxyapatite is 2:0.5-2.0.

[0020] As preferred, in the step S3, the catalyst is selected as EDC HCl catalyst.

[0021] As preferred, in the step S3, the reaction temperature is 30-40 DEG C, and the reaction time is 10-15 h.

[0022] As preferred, in the step S5, the mass ratio of the polyurethane prepolymer to the organic compound composite particle is 10:1-3.

[0023] The present application improves the adhesion of the ink by grafting the organic compound composite particle to the polyurethane through the reaction of the organic compound composite particle and the polyurethane prepolymer.

[0024] However, the inventors unexpectedly found that the ink sample often cracked under bending conditions, and after in-depth research, it was found that the cracking of the ink film layer was related to the amount of the organic compound composite particle.

[0025] As preferred, in the step S5, the chain extender added in the chain extension process is ethylenediamine.

[0026] A preparation method of a packaging box high-adhesion printing ink, comprising the following steps:

[0027] Titanium dioxide is added into deionized water and uniformly dispersed, then the modified waterborne polyurethane emulsion is added, and stirring is continued until the mixture is uniformly mixed.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] The modified waterborne polyurethane emulsion is used as the core film-forming material, the modified waterborne polyurethane emulsion forms hydrogen bonds with the substrate through polar groups, the hydroxyapatite / nano-cellulose micro-nano composite structure contained therein realizes mechanical anchoring through the "rivet effect", and the carboxymethyl chitosan modification enhances the compatibility, so that the adhesion of the ink to the substrate is improved under the multiple effects. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1SEM image of the surface of the composite particles prepared in the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application are described below clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application. In the specific embodiments, the hydroxyapatite used has a particle size of 5-10 nm; the nanocellulose used has a length of 1-5 μm and a diameter of 200-500 nm.

[0032] Embodiment 1

[0033] A packaging box high-adhesion printing ink comprises the following components in parts by weight:

[0034] 78 parts of modified water-based polyurethane emulsion, 37 parts of titanium white, 4 parts of hydroxypropyl methyl cellulose thickener, 4 parts of sodium dodecyl benzene sulfonate wetting agent, 2.5 parts of polyethylene glycol defoaming agent, and 68 parts of deionized water.

[0035] Preparation of modified water-based polyurethane emulsion:

[0036] Step 1: 3 g of epoxy silane coupling agent (KH-560) was added to 150 mL of ethanol solution (ethanol and water in a volume ratio of 9:1) and stirred to obtain a hydrolysis solution. 10 g of hydroxyapatite was weighed and added to the hydrolysis solution, and the reaction was carried out under the condition of a 75℃ water bath and magnetic stirring for 4 hours, with the pH controlled at 4.5 during the reaction. After the reaction was completed, centrifugal separation (8000 rpm, 15 min) was performed, and the white powder of epoxidized hydroxyapatite was obtained after washing with anhydrous ethanol for 3 times and vacuum drying at 60℃.

[0037] Step 2: 4 g of nanocellulose was weighed and dispersed in 200 mL of deionized water, and ultrasonic treatment was performed for 30 min (power 300 W). 3 g of epoxidized hydroxyapatite was added, and the reaction was carried out under the condition of an 80℃ oil bath and mechanical stirring (speed 500 rpm) for 6 hours. The reaction solution was filtered through a 0.22 μm microporous filter membrane, the filter cake was washed with deionized water until it was neutral, and freeze-drying was performed to obtain the composite particles.

[0038] Step 3: 3 g of carboxymethyl chitosan was dissolved in 150 mL of 0.1M MES buffer (pH=6.0), and 2 g of the composite particles, 0.15 g of EDC·HCl catalyst and 0.15 g of NHS were added, and the reaction was carried out at a constant temperature of 35℃ for 12 hours. After the reaction was completed, dialysis (molecular weight cut-off 8000 Da) was performed for 48 hours, and freeze-drying was performed to obtain the organic composite particles.

[0039] Step 4: Under the protection of dry nitrogen, 9 g of isophorone diisocyanate (IPDI), 0.05 g of dibutyl tin dilaurate, and 20 g of polybutylene adipate (Mn=2000) were weighed into a four-necked flask and reacted at 85°C for 3 hours. Then 2.5 g of dimethylol propionic acid (DMPA) was added, and the reaction was continued at 70°C for 1.5 hours to obtain a polyurethane prepolymer.

[0040] Step 5: 2.5 g of organic composite particles were weighed into 50 mL of acetone and ultrasonically treated for 1 hour. At 45°C, it was added dropwise to 10 g of polyurethane prepolymer, and after 2 hours of reaction, 2 g of triethylamine was added for neutralization. High-speed shearing emulsification (10000 rpm) was carried out while adding 200 mL of ice water, and finally 0.8 g of ethylenediamine was added for chain extension for 30 min. The solvent was removed by distillation under reduced pressure at 60°C to obtain a modified waterborne polyurethane emulsion.

[0041] The preparation method of the packaging box high-adhesion printing ink comprises the following steps:

[0042] The titanium dioxide was added to deionized water and dispersed uniformly, then the modified waterborne polyurethane emulsion was added, and the stirring was continued until the mixture was uniformly mixed. Then, hydroxypropyl methyl cellulose, sodium dodecylbenzenesulfonate, and polyethylene glycol were added in sequence, and the mixture was stirred uniformly to obtain the product.

[0043] Example 2

[0044] A packaging box high-adhesion printing ink comprises the following components by weight:

[0045] The modified waterborne polyurethane emulsion 73 parts, titanium dioxide 32 parts, hydroxypropyl methyl cellulose thickener 4 parts, sodium dodecylbenzenesulfonate wetting agent 4 parts, polyethylene glycol defoaming agent 2 parts, and deionized water 62 parts.

[0046] Preparation of the modified waterborne polyurethane emulsion:

[0047] Step 1: 3 g of epoxy silane coupling agent (KH-560) was added to 150 mL of ethanol solution (ethanol to water volume ratio 9:1) and stirred to obtain a hydrolysis solution. 10 g of hydroxyapatite was added to the hydrolysis solution, and the reaction was carried out under magnetic stirring at 75°C water bath for 4 hours, with the pH controlled at 4.5 during the reaction. After the reaction was completed, centrifugal separation (8000 rpm, 15 min) was carried out, and the white powder of epoxidized hydroxyapatite was obtained after washing with anhydrous ethanol 3 times and vacuum drying at 60°C.

[0048] Step 2: 4 g of nanocellulose was dispersed in 200 mL of deionized water and ultrasonically treated for 30 min (power 300 W). 2 g of epoxy hydroxyapatite was added, and the reaction was carried out at 80°C in an oil bath with mechanical stirring (speed 500 rpm) for 6 hours. The reaction solution was filtered through a 0.22 μm microporous filter membrane, the filter cake was washed with deionized water until neutral, and freeze-drying was carried out to obtain the composite particles.

[0049] Step 3: 3 g of carboxymethyl chitosan was dissolved in 150 mL of 0.1 M MES buffer (pH = 6.0), 2 g of composite particles, 0.15 g of EDC·HCl catalyst and 0.15 g of NHS were added, and the reaction was carried out at 35°C for 12 hours. After the reaction was completed, dialysis (molecular weight cutoff 8000 Da) was carried out for 48 hours, and freeze-drying was carried out to obtain organic composite particles.

[0050] Step 4: Under the protection of dry nitrogen, 9 g of isophorone diisocyanate (IPDI), 0.05 g of dibutyltin dilaurate and 20 g of polybutylene adipate (Mn = 2000) were added to a four-necked flask, and the reaction was carried out at 85°C for 3 hours. Then 2.5 g of dimethylol propionic acid (DMPA) was added, and the reaction was continued at 70°C for 1.5 hours to obtain a polyurethane prepolymer.

[0051] Step 5: 1.5 g of organic composite particles was dispersed in 50 mL of acetone and ultrasonically treated for 1 hour. It was added dropwise to 10 g of polyurethane prepolymer at 45°C, and after 2 hours of reaction, 2 g of triethylamine was added for neutralization. High-speed shearing emulsification (10000 rpm) was carried out while adding 200 mL of ice water, and finally 0.8 g of ethylenediamine was added for chain extension for 30 min. The solvent was removed by distillation under reduced pressure at 60°C to obtain a modified waterborne polyurethane emulsion.

[0052] The preparation method of the packaging box high-adhesion printing ink comprises the following steps:

[0053] The titanium dioxide was added to deionized water and dispersed uniformly, then the modified waterborne polyurethane emulsion was added, and the stirring was continued until the mixture was uniform. Then, hydroxypropyl methyl cellulose, sodium dodecylbenzenesulfonate and polyethylene glycol were added in sequence, and the stirring was uniform.

[0054] Example 3

[0055] A packaging box high-adhesion printing ink comprises the following components by weight:

[0056] Modified waterborne polyurethane emulsion 75 parts, titanium dioxide 35 parts, hydroxypropyl methyl cellulose thickener 4 parts, sodium dodecylbenzenesulfonate wetting agent 4 parts, polyethylene glycol defoaming agent 2 parts, deionized water 65 parts.

[0057] Preparation of modified waterborne polyurethane emulsion:

[0058] Step 1: 3 g of epoxy silane coupling agent (KH-560) was added to 150 mL of an ethanol solution (volume ratio of ethanol to water 9:1) and stirred to obtain a hydrolysis solution, 10 g of hydroxyapatite was weighed and added to the hydrolysis solution, and magnetic stirring was carried out under the condition of a 75°C water bath for 4 hours, and the pH was controlled at 4.5 during the reaction. After the reaction was completed, centrifugal separation (8000 rpm, 15 min) was performed, and the white powder of epoxidized hydroxyapatite was obtained after washing with anhydrous ethanol three times and vacuum drying at 60°C.

[0059] Step 2: 4 g of nanocellulose was dispersed in 200 mL of deionized water and ultrasonically treated for 30 min (power 300 W). 2.5 g of epoxidized hydroxyapatite was added, and mechanical stirring (speed 500 rpm) was carried out in an 80°C oil bath for 6 hours. The reaction solution was filtered through a 0.22 μm microporous filter membrane, the filter cake was washed with deionized water until neutral, and the composite particles were obtained by freeze-drying.

[0060] Step 3: 3 g of carboxymethyl chitosan was dissolved in 150 mL of 0.1 M MES buffer (pH = 6.0), 2 g of composite particles, 0.15 g of EDC·HCl catalyst and 0.15 g of NHS were added, and constant temperature reaction was carried out at 35°C for 12 hours. After the reaction was completed, dialysis (molecular weight cut-off 8000 Da) was carried out for 48 hours, and the organic composite particles were obtained by freeze-drying.

[0061] Step 4: Under the protection of dry nitrogen, 9 g of isophorone diisocyanate (IPDI), 0.05 g of dibutyltin dilaurate and 20 g of polybutylene adipate (Mn = 2000) were added to a four-necked flask, and reaction was carried out at 85°C for 3 hours. Then 2.5 g of dimethylol propionic acid (DMPA) was added, and the reaction was continued at 70°C for 1.5 hours to obtain a polyurethane prepolymer.

[0062] Step 5: 2 g of organic composite particles were dispersed in 50 mL of acetone and ultrasonically treated for 1 hour. At 45°C, 10 g of polyurethane prepolymer was added dropwise, and after 2 hours of reaction, 2 g of triethylamine was added for neutralization. High-speed shearing emulsification (10000 rpm) was carried out while adding 200 mL of ice water, and finally 0.8 g of ethylenediamine was added for chain extension for 30 min. The solvent was removed by distillation under reduced pressure at 60°C to obtain a modified waterborne polyurethane emulsion.

[0063] The preparation method of the packaging box high-adhesion printing ink comprises the following steps:

[0064] Titanium dioxide was added to deionized water and dispersed uniformly, then the modified waterborne polyurethane emulsion was added, and stirring was continued to mix uniformly, and then hydroxypropyl methyl cellulose, sodium dodecylbenzenesulfonate and polyethylene glycol were added in sequence, and stirring was carried out until uniform, and the product was obtained.

[0065] Example 4

[0066] A high adhesion printing ink for a packaging box, comprising the following components by weight parts:

[0067] Modified waterborne polyurethane emulsion 80 parts, titanium dioxide 40 parts, hydroxypropyl methyl cellulose thickening agent 5 parts, sodium dodecyl benzene sulfonate wetting agent 5 parts, polyethylene glycol defoaming agent 3 parts, deionized water 70 parts.

[0068] Preparation of modified waterborne polyurethane emulsion:

[0069] Step 1: 3g of epoxy silane coupling agent (KH-560) was added to 150mL of ethanol solution (ethanol to water volume ratio 9:1), stirred to obtain a hydrolysis solution, 10g of hydroxyapatite was weighed and added to the hydrolysis solution, and was magnetically stirred at 75℃ water bath for 4 hours, and the pH was controlled at 4.5 during the reaction. After the reaction was completed, centrifugal separation (8000rpm, 15min) was carried out, and the white powder of epoxidized hydroxyapatite was obtained after washing with anhydrous ethanol for 3 times and vacuum drying at 60℃.

[0070] Step 2: 4g of nanocellulose was dispersed in 200mL of deionized water, and was ultrasonically treated for 30min (power 300W). 4g of epoxidized hydroxyapatite was added, and was mechanically stirred (speed 500rpm) at 80℃ oil bath for 6 hours. The reaction solution was filtered through a 0.22μm microporous filter membrane, the filter cake was washed with deionized water until neutral, and freeze-drying was carried out to obtain composite particles.

[0071] Step 3: 3g of carboxymethyl chitosan was dissolved in 150mL of 0.1M MES buffer (pH=6.0), 2g of composite particles, 0.15g of EDC·HCl catalyst and 0.15g of NHS were added, and constant temperature reaction was carried out at 40℃ for 15 hours. After the reaction was completed, dialysis (molecular weight cut-off 8000Da) was carried out for 48 hours, and freeze-drying was carried out to obtain organic composite particles.

[0072] Step 4: Under the protection of dry nitrogen, 9g of isophorone diisocyanate (IPDI), 0.05g of dibutyltin dilaurate and 20g of polybutylene adipate (Mn=2000) were added to a four-necked flask, and reaction was carried out at 85℃ for 3 hours. Then 2.5g of dimethylol propionic acid (DMPA) was added, and reaction was continued at 70℃ for 1.5 hours to obtain a polyurethane prepolymer.

[0073] Step 5: 3g of organic composite particles were dispersed in 50mL of acetone, and ultrasonic treatment was carried out for 1 hour. 10g of polyurethane prepolymer was added dropwise at 45℃, and reaction was carried out for 2 hours, then 2g of triethylamine was added for neutralization. High-speed shearing emulsification (10000rpm) was carried out while 200mL of ice water was added, and finally 0.8g of ethylenediamine was added for chain extension for 30min. The solvent was removed by distillation under reduced pressure at 60℃ to obtain a modified waterborne polyurethane emulsion.

[0074] A method for preparing a high-adhesion printing ink for a packaging box, comprising the following steps:

[0075] Titanium dioxide is added into deionized water and dispersed uniformly, then modified waterborne polyurethane emulsion is added, and stirring is continued until the mixture is uniform. Hydroxypropyl methyl cellulose, sodium dodecyl benzene sulfonate and polyethylene glycol are added in sequence, and stirring is uniform. The preparation is obtained.

[0076] Example 5

[0077] A high-adhesion printing ink for a packaging box, comprising the following components by weight:

[0078] Modified waterborne polyurethane emulsion 70 parts, titanium dioxide 30 parts, hydroxypropyl methyl cellulose thickener 3 parts, sodium dodecyl benzene sulfonate wetting agent 3 parts, polyethylene glycol defoaming agent 1 part, and deionized water 60 parts.

[0079] Preparation of modified waterborne polyurethane emulsion:

[0080] Step 1: 3g of epoxy silane coupling agent (KH-560) is added into 150mL of ethanol solution (ethanol and water volume ratio 9:1), and stirring is performed to obtain a hydrolysis solution. 10g of hydroxyapatite is weighed and added into the hydrolysis solution, and magnetic stirring is performed under the condition of 75℃ water bath for 4 hours. The pH is controlled at 4.5 during the reaction. After the reaction is completed, centrifugal separation (8000rpm, 15min) is performed, and the white powder of epoxidized hydroxyapatite is obtained after washing with anhydrous ethanol for 3 times and vacuum drying at 60℃.

[0081] Step 2: 4g of nanocellulose is weighed and dispersed in 200mL of deionized water, and ultrasonic treatment is performed for 30min (power 300W). 1g of epoxidized hydroxyapatite is added, and mechanical stirring (speed 500rpm) is performed in an 80℃ oil bath for 6 hours. The reaction liquid is filtered by a 0.22μm microporous filter membrane, the filter cake is washed with deionized water until it is neutral, and freeze-drying is performed to obtain composite particles.

[0082] Step 3: 3g of carboxymethyl chitosan is dissolved in 150mL of 0.1M MES buffer (pH=6.0), 2g of composite particles, 0.15g of EDC·HCl catalyst and 0.15g of NHS are added, and constant temperature reaction is performed at 30℃ for 10 hours. After the reaction is completed, dialysis (molecular weight cut-off 8000Da) is performed for 48 hours, and freeze-drying is performed to obtain organic composite particles.

[0083] Step 4: Under the protection of dry nitrogen, 9 g of isophorone diisocyanate (IPDI), 0.05 g of dibutyl tin dilaurate, and 20 g of polybutylene adipate (Mn=2000) were weighed into a four-necked flask and reacted at 85°C for 3 hours. Then 2.5 g of dimethylol propionic acid (DMPA) was added, and the reaction was continued at 70°C for 1.5 hours to obtain a polyurethane prepolymer.

[0084] Step 5: 1 g of organic composite particles was dispersed in 50 mL of acetone and ultrasonically treated for 1 hour. It was added dropwise to 10 g of polyurethane prepolymer at 45°C, and after 2 hours of reaction, 2 g of triethylamine was added for neutralization. High-speed shearing emulsification (10000 rpm) was carried out while adding 200 mL of ice water, and finally 0.8 g of ethylenediamine was added for chain extension for 30 min. The solvent was removed by distillation under reduced pressure at 60°C to obtain a modified waterborne polyurethane emulsion.

[0085] The preparation method of the packaging box high-adhesion printing ink comprises the following steps:

[0086] The titanium dioxide was added to deionized water and dispersed uniformly, then the modified waterborne polyurethane emulsion was added, and the stirring was continued until the mixture was uniform. Then, hydroxypropyl methyl cellulose, sodium dodecylbenzenesulfonate, and polyethylene glycol were added in sequence and stirred uniformly to obtain the product.

[0087] Comparative Example 1

[0088] The difference between Comparative Example 1 and Example 1 is that the modified waterborne polyurethane emulsion is replaced by a common waterborne polyurethane emulsion on the market.

[0089] Comparative Example 2

[0090] The difference between Comparative Example 2 and Example 1 is that in the preparation process of the modified waterborne polyurethane emulsion, the polyurethane only grafts carboxymethyl chitosan, but not hydroxyapatite and nanocellulose.

[0091] Comparative Example 3

[0092] The difference between Comparative Example 3 and Example 1 is that in the preparation process of the modified waterborne polyurethane emulsion, the nanocellulose surface does not combine with hydroxyapatite.

[0093] Comparative Example 4

[0094] The difference between Comparative Example 4 and Example 4 is that the mass ratio of polyurethane prepolymer to organic composite particles is 10:4.

[0095] Performance test:

[0096] 1. Adhesion test: According to GB / T 5210-2006 standard, use the pull-off adhesion tester to test. The printing surface of the test sample is bonded with a special test column through an adhesive, after the adhesive is completely cured, the sample is installed on the tester, a pulling force is applied at a certain rate until the test column and the sample are separated, and the maximum pulling force value at this time is recorded. According to the bonding area of the test column, the adhesion is calculated, the unit is MPa, the greater the adhesion, the stronger the adhesion of the ink to the substrate. The test results are shown in Table 1.

[0097] 2. Anti-cracking performance test: cut the test sample from the packaging box printed with the ink, the test sample is 50mm x 25mm, ensure that the test sample surface is flat, wrinkle-free, and the printed ink layer uniformly covers the entire test sample area. Use a bending tester to bend at an angle of 180° for 50 times at 25°C. Place the bent test piece under a metallographic microscope, adjust the magnification to 100 times, and observe the test piece surface comprehensively, record the number of cracks, the length and width of the cracks. The test results are shown in Table 1.

[0098] 3. Whiteness test: use the whiteness meter to test the sample printed with the ink according to GB / T 2913-2008 standard, randomly select 5 different test points on the surface of the sample, measure and record the whiteness value, take the average value as the whiteness of the sample, the higher the whiteness value, the better the whiteness of the ink. The test results are shown in Table 1.

[0099] 4. Water resistance test: according to GB / T 1733-1993 standard, immerse the sample printed with the ink in deionized water at 25°C, take it out after soaking for 24h, dry the surface water with filter paper, observe whether the ink layer appears blistering, peeling and other phenomena. The test results are shown in Table 1.

[0100] Table 1:

[0101] Table 1:

[0102]

[0103] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part of the technical features, any modification, equivalent substitution, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A packaging box high adhesion printing ink, characterized by, Comprise the following components by weight parts: Modified waterborne polyurethane emulsion 70~80 parts, titanium dioxide 30~40 parts, hydroxypropyl methyl cellulose 3~5 parts, sodium dodecyl benzene sulfonate 3~5 parts, polyethylene glycol 1~3 parts, deionized water 60~70 parts; The preparation method of the modified waterborne polyurethane emulsion comprises the following steps: S1, hydroxyapatite is added to the epoxy silane coupling agent hydrolysate, heated and reacted to obtain epoxidized hydroxyapatite, wherein the particle size of the hydroxyapatite is 5~10 nm; S2, nanocellulose is dispersed in deionized water, then epoxidized hydroxyapatite is added, and heated and reacted to obtain composite particles, wherein the length of the nanocellulose is 1~5 μm, and the diameter is 200~500 nm; S3, carboxymethyl chitosan is dissolved in a buffer to form a carboxymethyl chitosan solution, then the composite particles are added, and heated and reacted under the action of a catalyst to obtain organic composite particles; S4, isophorone diisocyanate and dibutyl tin dilaurate are added to polybutylene adipate, heated and reacted, then dimethylol propionic acid is added, and the reaction is continued to obtain a polyurethane prepolymer; S5, the organic composite particles are dispersed in acetone, uniformly dispersed by ultrasonic, then slowly added to the polyurethane prepolymer for reaction, and the mass ratio of the polyurethane prepolymer to the organic composite particles is 10:1~3, after neutralization, emulsification, chain extension and reduced pressure distillation, a modified waterborne polyurethane emulsion is obtained.

2. The packaging box high adhesion printing ink according to claim 1, characterized in that, In the step S2, the mass ratio of nanocellulose to epoxidized hydroxyapatite is 2:0.5~2.

0.

3. The packaging box high adhesion printing ink according to claim 1, characterized in that, In the step S3, the catalyst is selected from EDC·HCl catalyst.

4. The packaging box high adhesion printing ink according to claim 1, characterized in that, In the step S3, the reaction temperature is 30~40℃, and the reaction time is 10~15 h.

5. The packaging box high adhesion printing ink according to claim 1, characterized in that, In the step S5, the chain extender is ethylenediamine during the chain extension process.

6. A process for preparing a high adhesion printing ink for cartons as claimed in any one of claims 1 to 5, characterized in that Comprise the following steps: Titanium dioxide is added to deionized water and dispersed uniformly, then the modified waterborne polyurethane emulsion is added, and the stirring is continued to mix uniformly, then hydroxypropyl methyl cellulose, sodium dodecyl benzene sulfonate and polyethylene glycol are added in sequence, and stirred uniformly to obtain the product.

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