A retort-resistant water-based ink binder suitable for high-speed printing and its application

Abstract

This invention discloses a retort-resistant water-based ink binder suitable for high-speed printing and its application. The water-based ink binder comprises: a small-particle-size aqueous polyurethane emulsion containing hydrazide groups and a large-particle-size aqueous polyacrylate emulsion containing ketone carbonyl groups. On one hand, after the aqueous polyacrylate emulsion and the aqueous polyurethane emulsion are compounded, the small-particle-size aqueous polyurethane emulsion can stabilize the large-particle-size aqueous polyacrylate emulsion, and it does not break down after dilution with 0-60wt% alcohol, exhibiting excellent alcohol dilution stability. Furthermore, the addition of alcohol helps to increase the printing speed of the water-based ink. On the other hand, the composite binder resin can undergo ketone hydrazide self-crosslinking during drying, which, compared to general water-based ink printing resins, can meet the retort-resistant requirements after water-based ink printing. The retort-resistant water-based ink binder can meet the requirements for high-temperature retort sterilization in printing applications such as food, pharmaceuticals, beverages, and children's toys.

Description

Technical Field

[0001] This invention relates to the field of water-based ink printing, and more particularly to a water-based ink binder that can be used to formulate various colors of water-based ink, including white, black, red, yellow, blue, etc., to achieve high-speed printing of water-based ink at a speed of 30-300m / s; at the same time, it meets the requirement of not deforming or fading after being boiled at 120℃ for 30 minutes after printing. Background Technology

[0002] With the development of the social economy and the increasing environmental awareness of people, the inks used for printing various plastic films in the market are shifting from traditional organic solvent-based inks to water-based inks. Traditional organic solvent-based inks cause air pollution due to the volatilization and emission of organic solvents during the printing process; they are also detrimental to the health of operators during printing and pose certain hazards to product users. Water-based inks, compared to traditional solvent-based inks, have advantages in terms of being green, environmentally friendly, safe, and sustainable. For example, in packaging printing products with strict hygiene requirements, such as food, pharmaceuticals, beverages, and children's toys, using water-based inks instead of organic solvent-based inks avoids the use of organic solvents, thus better ensuring product safety. The composition and structure of packaging materials are as follows... Figure 9 As shown.

[0003] Water-based inks are mainly composed of resin, pigments, water, and various additives. Among these, the water-based resin binder is a key factor affecting the printing performance of water-based inks, significantly influencing their storage stability, printing speed, and post-printing adhesion. However, in existing water-based ink products, due to the good hydrophilicity of water-based resins, the water resistance of the printed ink is generally poor, making it difficult to meet the high-temperature sterilization requirements of water-based ink printing products such as food, pharmaceuticals, beverages, and children's toys, which have stringent hygiene requirements.

[0004] On the other hand, due to the high specific heat capacity of water-based solvents, it is difficult to heat them during production to increase the evaporation rate of the aqueous solution. Currently, the evaporation rate of the solvent is often increased by adding small-molecule alcohols to the water-based ink system. Ethanol is the most commonly used alcohol, with advantages such as being environmentally friendly and having no VOC emissions. Therefore, the addition of alcohol helps to achieve rapid printing of water-based inks. However, general water-based polyacrylate resin emulsions usually have a suitable amount of small-molecule emulsifiers added during the production process to ensure the stability of the emulsion. The addition of a large amount of alcohol will dissolve the small-molecule emulsifiers, causing the resin emulsion particles to break down, which limits the use of alcohol in water-based ink systems. Summary of the Invention

[0005] To address the problems of poor water resistance and slow production speed in existing water-based ink printing products, this invention discloses a water-based ink binder suitable for high-speed printing, its preparation method, and its application. The binder is a stable water-based composite resin emulsion obtained by compounding an aqueous polyurethane emulsion containing terminal hydrazine groups and an aqueous polyacrylate emulsion containing ketone carbonyl groups in a certain proportion, followed by dilution with 0-60wt% alcohol. When formulated into a water-based ink, this binder enables high-speed printing in production, and upon drying, ketone hydrazine self-crosslinking occurs, achieving the required water resistance to boiling after printing.

[0006] This invention can meet the high-temperature sterilization requirements of water-based ink printing products with strict hygiene conditions, such as food, pharmaceuticals, beverages, and children's toys.

[0007] The technical solution of this invention is as follows: A water-based composite resin emulsion suitable for high-speed printing and resistant to boiling is obtained by compounding an aqueous polyurethane emulsion containing hydrazide groups and an aqueous polyacrylate emulsion containing ketone carbonyl groups in a certain proportion. The hydrazide group in the aqueous polyurethane emulsion has a functionality greater than or equal to two, giving it alcohol dilution stability. The particle size of the aqueous polyurethane emulsion is 10-100 nm, and the particle size of the aqueous polyacrylate emulsion is 100-300 nm. The molar ratio of the hydrazide groups in the aqueous polyurethane emulsion to the ketone carbonyl groups in the aqueous polyacrylate emulsion is between 10:1 and 1:10. During the drying process, the aqueous composite resin emulsion undergoes a ketone-hydrazide crosslinking reaction as water evaporates, forming a resin film with a crosslinked network structure, exhibiting excellent resistance to boiling.

[0008] More importantly, this invention, based on the surface potential of polyurethane particles and polyacrylate particles, and through the ratio of large to small particle sizes of polyurethane emulsion and aqueous polyacrylate emulsion, achieves this by causing the emulsifier on the surface of large-particle polyacrylate latex particles to lose its emulsifying effect and the electrostatic repulsion of ions on the surface to disappear in an alcohol environment. This induces the polyurethane emulsion to adsorb onto the surface of the polyacrylate latex particles, forming composite particles of polyacrylate encapsulated by polyurethane latex particles. These composite particles remain stable in the alcohol system due to the mutual repulsion of ionic groups on the surface of the polyurethane emulsion. After dilution with alcohol, this aqueous composite resin emulsion does not exhibit demulsification or stratification (e.g., ...). Figure 10As shown); specifically, if the collision rate between polyacrylate latex particles is less than the collision rate between polyurethane latex particles and polyacrylate latex particles, the system tends for polyurethane latex particles to adsorb onto the surface of polyacrylate latex particles. Sufficient adsorption of polyurethane latex particles onto the surface of polyacrylate latex particles will stabilize the polyacrylate latex particles. If the collision rate between polyacrylate latex particles is greater, the polyacrylate latex particles tend to agglomerate and demulsify. Therefore, this application further addresses the above-mentioned demulsification problem by the difference in the collision and agglomeration rates of the two particles (the collision rate between polyacrylate latex particles and the collision rate between polyurethane latex particles and polyacrylate latex particles), and controls the difference between the two rates by controlling their sizes. Specifically, as follows:

[0009] Secondly, the rate parameters for particle collisions and aggregation in the mixed solution of the two types of particles include Brownian diffusion collisions ( ) and sedimentation aggregation ( It consists of two parts:

[0010]

[0011] in, , ;

[0012] i and j represent two types of particles, respectively, and r is the particle radius. Let be the fluid viscosity, k be the Boltzmann constant, T be the temperature, and g be the gravitational constant. For particle density, The density is the medium.

[0013] It is evident that particle size has a significant impact on the difference (ratio) between the two rates. Preferably, the particle size of the aqueous polyurethane emulsion is 20-50 nm; the particle size of the aqueous polyacrylate emulsion is 250-300 nm.

[0014] On the other hand, adding an appropriate amount of reactive emulsifier during the synthesis of waterborne polyacrylate emulsions can further improve the alcohol resistance of the resin emulsions.

[0015] It should be noted that different blending ratios of waterborne polyurethane emulsion and waterborne polyacrylate emulsion in the water-based ink binder can alter the degree of crosslinking of the resulting film after drying the waterborne composite resin emulsion, thereby adjusting its mechanical properties. Furthermore, it can reduce the cost of the waterborne composite resin. Therefore, those skilled in the art can adjust the ratio of the two components according to actual needs.

[0016] In some embodiments of the present invention, the waterborne polyurethane emulsion containing hydrazine groups in the retort-resistant water-based ink binder is prepared by the following method: Polyol, isocyanate, hydrophilic chain extender, small molecule chain extender, and salt-forming agent are reacted in acetone at 50-85°C for 5-10 hours to obtain an isocyanate-terminated polyurethane prepolymer. The temperature is then lowered to 30-70°C, and a multifunctional hydrazine monomer and deionized water are added for emulsification for 0.5-3 hours. Acetone is then removed by vacuum distillation to obtain the hydrazine-terminated waterborne polyurethane emulsion. The proportions of each raw material by mass are as follows: polyol: 10-60 parts; isocyanate: 10-60 parts; hydrophilic chain extender: 3-20 parts; small molecule chain extender: 3-20 parts; salt-forming agent: 2-16 parts; deionized water: 50-70 parts; acetone: 20-30 parts; hydrazine monomer: 5-15 parts; the total content of all raw materials is 100 parts.

[0017] As is common knowledge in this field, the structure of polyurethane polymer chains can be modulated into linear or branched structures using multifunctional small-molecule chain extenders to increase the crosslinkable reaction sites in polyurethane and achieve better crosslinking effects in waterborne composite resin emulsions, such as... Figure 11 As shown.

[0018] The aforementioned polyols are one or more of polyester polyols, polycarbonate polyols, polyether polyols, organosilicon polyols, and polyacrylate polyols;

[0019] The above-mentioned isocyanates are one or more of the diisocyanates, such as isophorone diisocyanate, 1,6-hexyl diisocyanate, dicyclohexylmethane diisocyanate, tetramethylcyclohexylmethane diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, etc.

[0020] The above-mentioned hydrophilic chain extender is one or more of dimethylolpropionic acid (DMPA), sodium ethylenediaminoethanesulfonate, diethylenetriamine, and methyldiethanolamine;

[0021] The aforementioned small molecule chain extenders are multifunctional alcohols or amines, including one or more of the following: 1,4-butanediol, ethylene glycol, methyl propylene glycol, 1,2-propanediol, glycerol, trimethylolpropane, octene glycol, 1,4-cyclohexanediethanolamine, ethylenediamine, dibutylamine, diethylenetriamine, and N-methyldiethanolamine.

[0022] The salt-forming agent mentioned above is one or more of triethylamine, ammonia, and N,N-dimethylisopropylamine;

[0023] The multifunctional hydrazide monomers used for end capping are one or more of adipic dihydrazide, sebacic dihydrazide, heptanic dihydrazide, octanoic dihydrazide, succinic dihydrazide, azelaic dihydrazide, and hexane dihydrazide.

[0024] In some embodiments of the present invention, the waterborne polyacrylate emulsion containing ketone carbonyl in the retort-resistant water-based ink binder is prepared by the following method: An acrylate monomer, a ketone carbonyl acrylate monomer, an emulsifier, and water are stirred to form a pre-emulsion; 5-50% of the pre-emulsion is first added to an initiator, and reacted at 40-95°C for 0.1-2 hours, maintaining the temperature at 60-95°C; then the remaining pre-emulsion is added dropwise to the reaction system at a uniform rate over 2-5 hours, and the reaction continues for 1-3 hours after the addition is complete to obtain the waterborne polyacrylate emulsion containing ketone carbonyl; wherein, the ketone carbonyl acrylate monomer accounts for 5-30% of the total reactant monomers; the emulsifier accounts for 5-30% of the total reactant monomers, and at least a portion of the emulsifier is a reactive emulsifier, accounting for less than 20% of the total reactant monomers; the initiator accounts for 0.1% to 5% of the total reactant monomers. As is common knowledge in the art, copolymerization is carried out under an inert gas atmosphere.

[0025] The above-mentioned acrylate monomers are one or more of the following: n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, isooctyl acrylate, methyl methacrylate, and acrylic acid.

[0026] The aforementioned ketone carbonyl acrylate monomers are at least one of diacetone acrylamide and hydroxymethyl diacetone acrylamide;

[0027] The emulsifiers mentioned above are one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium styrene sulfonate;

[0028] The aforementioned initiator is an inorganic peroxide initiator, including at least one of potassium persulfate, sodium persulfate, and ammonium persulfate;

[0029] The water-based ink binder and pigment of the present invention are diluted with a diluent to obtain water-based ink; the diluent contains alcohol; the water-based ink can be widely used in water-based ink printing products that require high-temperature cooking, such as food, pharmaceuticals, beverages and children's toys.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) The water-based ink binder provided by the present invention is used to configure water-based inks of various colors. When water-based ink printing is carried out, it has the function of self-crosslinking at room temperature, so that the printed packaging material has excellent water-based ink resistance and can meet the requirements of high-temperature cooking sterilization for water-based ink printed products with strict hygiene requirements such as food, medicine, beverage and children's toys.

[0032] (2) The water-based ink binder provided by the present invention has good alcohol dilution stability, which can accelerate the drying speed of the water-based ink prepared therefrom, thereby effectively speeding up the printing rate. Attached Figure Description

[0033] Figure 1 Photos of different water-based resin emulsions diluted with 60wt% alcohol.

[0034] Figure 2 The gel content of films prepared from different waterborne composite resins obtained by blending linear waterborne polyurethane emulsion and waterborne polyacrylate emulsion.

[0035] Figure 3 The gel content of films prepared from aqueous composite resins with different ketone-hydrazine ratios obtained by compounding linear aqueous polyurethane emulsions and aqueous polyacrylate emulsions.

[0036] Figure 4 Tensile strength tests were conducted on films prepared from aqueous composite resins with different ketone-hydrazine ratios obtained by compounding linear aqueous polyurethane emulsions and aqueous polyacrylate emulsions.

[0037] Figure 5 Test of elongation at break of films prepared from aqueous composite resins with different ketone-hydrazine ratios obtained by compounding linear aqueous polyurethane emulsions and aqueous polyacrylate emulsions.

[0038] Figure 6 The gel content of waterborne composite resin emulsions with different ketone-hydrazine ratios obtained by compounding branched waterborne polyurethane emulsions and waterborne polyacrylate emulsions.

[0039] Figure 7 Tensile strength tests were conducted on films prepared from waterborne composite resins with different ketone-hydrazine ratios obtained by compounding branched waterborne polyurethane emulsions and waterborne polyacrylate emulsions.

[0040] Figure 8 Test of elongation at break of films prepared from waterborne composite resins with different ketone-hydrazine ratios obtained by compounding branched waterborne polyurethane emulsions and waterborne polyacrylate emulsions.

[0041] Figure 9 This is a schematic diagram of the composition and structure of packaging materials.

[0042] Figure 10 This is a schematic diagram of the microsphere state in an aqueous composite resin emulsion system.

[0043] Figure 11 Schematic diagrams of linear (1) and multi-branched (2) waterborne polyurethane structures. Detailed Implementation

[0044] To address the shortcomings of existing technologies, this invention provides a retort-resistant water-based ink binder suitable for high-speed printing and its applications. The water-based ink binder provided by this invention can be used in the formulation of water-based inks. By cross-linking the two components of the binder during the printing and drying process, the retort resistance of the printed water-based ink is improved. Simultaneously, the combination of the two components of the binder solves the problem of demulsification when water-based emulsions encounter alcohol. In other words, the binder of this invention can use alcohol as a solvent, thereby significantly increasing printing speed; and its self-crosslinking function during drying enables its widespread application in water-based ink printing products requiring high-temperature retort, such as food, pharmaceuticals, beverages, and children's toys.

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0046] Unless otherwise specified, the operating methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages in the following examples are by mass.

[0047] In the following examples, the polyester polyol was purchased from Stepan Chemical, brand name STEPANPOL PC-1011-55, and other chemicals were purchased from the National Pharmaceutical Reagent Network.

[0048] Example 1:

[0049] A method for preparing a retort-resistant water-based ink binder suitable for high-speed printing, comprising the following steps:

[0050] (1) Preparation of linear waterborne polyurethane emulsion

[0051] Preparation of small-particle-size hydrazide-terminated waterborne polyurethane (PU-S-1): 100g of polyester diol and 50g of isoflurane diisocyanate (IPDI) were added to a 1L three-necked flask and reacted at 80℃ and 200r / min for 3 hours. Then, the temperature was lowered to 60℃, and 12g of hydrophilic chain extender dimethylolpropionic acid (DMPA), 4g of small-molecule chain extender 1,4-butanediol (BDO), 7.4g of salt-forming agent N,N-dimethylisopropylamine (DTPA), and 50g of acetone were added sequentially. The reaction was maintained at 60℃ for another 4 hours. Subsequently, the system was cooled to below 40℃, the rotation speed was adjusted to 800r / min, and 300g of deionized water containing 4g of adipic acid dihydrazide (ADH) was added and emulsified for 15 minutes. Finally, acetone was removed by vacuum distillation to obtain small-particle-size hydrazide-terminated waterborne polyurethane (PU-S-1).

[0052] Preparation of small-particle-size, hydrazine-free, end-capped waterborne polyurethane (PU-S-2): 100g of polyester diol and 50g of IPDI were added to a 1L three-necked flask and reacted at 80℃ and 200r / min for 3 hours. Then, the temperature was lowered to 60℃, and 12g of DMPA, 4g of BDO, 7.4g of DTPA, and 50g of acetone were added sequentially. The reaction was maintained at 60℃ for another 4 hours. Subsequently, the system was cooled to below 40℃, the stirring speed was adjusted to 800r / min, and 300g of a deionized aqueous solution containing 1.3g of ethylenediamine (EDA) was added and emulsified for 15 minutes. Finally, acetone was removed by vacuum distillation to obtain small-particle-size, hydrazine-free, end-capped waterborne polyurethane (PU-S-2).

[0053] Preparation of small-particle-size hydrazide-terminated waterborne polyurethane (PU-S-3): 100g of polyester diol and 50g of IPDI were added to a 1L three-necked flask and reacted at 80℃ and 200r / min for 3 hours. Then, the temperature was lowered to 60℃, and 15g of DMPA, 2g of BDO, 9.2g of DTPA, and 50g of acetone were added sequentially. The reaction was maintained at 60℃ for another 4 hours. Subsequently, the system was cooled to below 40℃, the stirring speed was adjusted to 1200r / min, and 300g of a deionized aqueous solution containing 4g of adipic acid diazid (ADH) was added and emulsified for 15 minutes. Finally, acetone was removed by vacuum distillation to obtain small-particle-size hydrazide-terminated waterborne polyurethane (PU-S-3).

[0054] Preparation of small-particle-size hydrazide-terminated waterborne polyurethane (PU-S-4): 100g of polyester diol and 50g of IPDI were added to a 1L three-necked flask and reacted at 80℃ and 200r / min for 3 hours. Then, the temperature was lowered to 60℃, and 9g of DMPA, 6g of BDO, 5.6g of DTPA, and 50g of acetone were added sequentially. The reaction was maintained at 60℃ for another 4 hours. Subsequently, the system was cooled to below 40℃, the stirring speed was adjusted to 800r / min, and 300g of a deionized aqueous solution containing 4g of adipic acid dihydrazide (ADH) was added and emulsified for 15 minutes. Finally, acetone was removed by vacuum distillation to obtain small-particle-size hydrazide-terminated waterborne polyurethane (PU-S-4).

[0055] Preparation of large-particle-size hydrazide-terminated waterborne polyurethane (PU-L-1): 100g of polyester diol and 50g of IPDI were added to a 1L three-necked flask and reacted at 80℃ and 200 rpm for 3 hours. Then, the temperature was lowered to 60℃, and 6g of DMPA, 8g of BDO, 3.7g of DTPA, and 50g of acetone were added sequentially. The reaction was maintained at 60℃ for another 4 hours. Subsequently, the system was cooled to below 40℃, the stirring speed was adjusted to 600 rpm, and 300g of a deionized aqueous solution containing 4g of ADH was added and emulsified for 15 minutes. Finally, acetone was removed by vacuum distillation to obtain large-particle-size hydrazide-terminated waterborne polyurethane (PU-L-1).

[0056] Preparation of large-particle-size hydrazide-free end-capped waterborne polyurethane (PU-L-2): 100g of polyester diol and 50g of IPDI were added to a 1L three-necked flask and reacted at 80℃ and 200 rpm for 3 hours. Then, the temperature was lowered to 60℃, and 6g of DMPA, 8g of BDO, 3.7g of DTPA, and 50g of acetone were added sequentially. The reaction was maintained at 60℃ for another 4 hours. Subsequently, the system was cooled to below 40℃, the stirring speed was adjusted to 600 rpm, and 300g of a deionized aqueous solution containing 1.3g of EDA was added and emulsified for 15 minutes. Finally, acetone was removed by vacuum distillation to obtain large-particle-size hydrazide-end-capped waterborne polyurethane (PU-L-2).

[0057] (2) The aqueous polyacrylate emulsion is prepared by the following steps:

[0058] Preparation of a ketone-containing carbonyl aqueous polyacrylate emulsion (PA-1) with a reactive emulsifier: 280g deionized water, 100g n-butyl acrylate (BA), 100g methyl methacrylate (MMA), 3g acrylic acid (AA), 5g diacetone acrylamide (DAAM), 2g sodium p-styrene sulfonate (MSDS), and 6g sodium dodecylbenzene sulfonate (SDBS) were mechanically mixed to prepare a pre-emulsion, wherein sodium p-styrene sulfonate (MSDS) was the reactive emulsifier. Then, 20g of the pre-emulsion was added to a 1L three-necked flask, stirred, and heated to 70°C. 0.45g of sodium persulfate initiator was then added and reacted for 30 minutes. The remaining pre-emulsion was then added slowly dropwise over 3 hours, and the reaction was continued for another hour to obtain the ketone-containing carbonyl aqueous polyacrylate emulsion (PA-1) with the reactive emulsifier.

[0059] Preparation of a ketone-free carbonyl-free aqueous polyacrylate emulsion (PA-2) with a reactive emulsifier: 280g deionized water, 105g BA, 100g MMA, 3g AA, 2g MSDS, and 6g SDBS were mechanically mixed to prepare a pre-emulsion. Then, 20g of the pre-emulsion was added to a 1L three-necked flask, stirred, and heated to 70°C. 0.45g of sodium persulfate initiator was then added, and the reaction was allowed to proceed for 30 minutes. The remaining pre-emulsion was then added slowly dropwise over 3 hours. After the addition was complete, the reaction was continued for another hour to obtain the ketone-free carbonyl-free aqueous polyacrylate emulsion (PA-2) with a reactive emulsifier.

[0060] Preparation of a ketone-free carbonyl-based aqueous polyacrylate emulsion (PA-3) with a reactive emulsifier: 280g deionized water, 105g BA, 100g MMA, 6g AA, 4g MSDS, and 10g SDBS were mechanically mixed to prepare a pre-emulsion. Then, 20g of the pre-emulsion was added to a 1L three-necked flask, stirred, and heated to 70°C. 0.45g of sodium persulfate initiator was then added, and the reaction was allowed to proceed for 30 minutes. The remaining pre-emulsion was then added slowly dropwise over 3 hours. After the addition was complete, the reaction was continued for another hour to obtain the ketone-free carbonyl-based aqueous polyacrylate emulsion with a reactive emulsifier.

[0061] Preparation of a ketone-free, carbonyl-free aqueous polyacrylate emulsion (PA-4) with a reactive emulsifier:

[0062] A preemulsion was prepared by mechanically mixing 280g deionized water, 105g BA, 100g MMA, 4g AA, 3g MSDS, and 8g SDBS. Then, 20g of the preemulsion was added to a 1L three-necked flask, stirred, and heated to 70°C. 0.45g of sodium persulfate initiator was then added, and the reaction was allowed to proceed for 30 minutes. The remaining preemulsion was then added slowly dropwise over 3 hours, followed by a further 1 hour of reaction to obtain a ketone-free, carbonyl-free aqueous polyacrylate emulsion containing a reactive emulsifier.

[0063] Preparation of a ketone-containing carbonyl aqueous polyacrylate emulsion (PA-5) without reactive emulsifiers: 280g deionized water, 100g BA, 100g MMA, 3g AA, 5g DAAM, and 8g SDBS were mechanically mixed to prepare a pre-emulsion. Then, 20g of the pre-emulsion was added to a 1L three-necked flask, stirred, and heated to 70°C. 0.45g of sodium persulfate initiator was then added, and the reaction was allowed to proceed for 30 minutes. The remaining pre-emulsion was then added slowly dropwise over 3 hours. After the addition was complete, the reaction was continued for another hour to obtain the ketone-containing carbonyl aqueous polyacrylate emulsion (PA-5) without reactive emulsifiers.

[0064] Preparation of a ketone-carbonyl-free aqueous polyacrylate emulsion (PA-6) without reactive emulsifiers: 280g deionized water, 105g BA, 100g MMA, 3g AA, and 8g SDBS were mechanically mixed to prepare a pre-emulsion. Then, 20g of the pre-emulsion was added to a 1L three-necked flask, stirred, and heated to 70°C. 0.45g of sodium persulfate initiator was then added, and the reaction was allowed to proceed for 30 minutes. The remaining pre-emulsion was then added slowly dropwise over 3 hours. After the addition was complete, the reaction was continued for another hour to obtain a ketone-carbonyl-containing aqueous polyacrylate emulsion (PA-6) without reactive emulsifiers.

[0065] (3) The linear waterborne polyurethane emulsion and waterborne polyacrylate emulsion prepared in steps (1) and (2) are compounded in different proportions to obtain different waterborne composite resin emulsions.

[0066] The resin emulsions obtained in steps (1), (2) and (3) were subjected to alcohol dilution stability tests; at the same time, the resin obtained in step (3) was dried to form a film, and mechanical tensile and gel content tests were performed on different films. The film formation steps are as follows: 5g of emulsion was placed in a 7*7cm PTFE mold, and dried naturally at room temperature for 3 days, and then heat-treated in a 60℃ oven for 1 day to obtain the film.

[0067] Table 1. Properties of single resin emulsions and their alcohol dilution stability test

[0068]

[0069] Table 2. Stability test of different water-based composite resin emulsions after alcohol dilution.

[0070]

[0071] *In Table 2, the resin mass ratio of PU:PA in waterborne composite resins 2-4 and 6-8 is 1:1.

[0072] Table 3. Alcohol dilution stability test of aqueous composite resin emulsions with different ketone-hydrazine ratios.

[0073]

[0074] Table 1 shows the performance of single resin emulsions and their alcohol dilution stability test results. As can be seen from Table 1, all waterborne polyurethane emulsions exhibit good alcohol dilution stability, but waterborne polyacrylate emulsions show poor alcohol dilution stability. Even with the addition of reactive emulsifiers, their storage stability is only one month. Waterborne polyacrylate emulsions without reactive emulsifiers demulsify directly upon contact with alcohol; therefore, resins PA-5 and PA-6 were not included in subsequent tests.

[0075] Table 2 shows the alcohol dilution stability test results of different waterborne composite resin emulsions. As can be seen from Table 2, the alcohol dilution stability of the waterborne composite resin emulsions obtained by blending two emulsions varies. The composite resin emulsions blended with small-particle-size waterborne polyurethane emulsions (PU-S-1, PU-S-2, PU-S-3, and PU-S-4) and polyacrylate emulsions with reactive emulsifiers (PA-1, PA-2, PA-3, and PA-4) all exhibit good alcohol dilution stability. Among these, large-particle-size waterborne polyurethane emulsions (PU-L-1 and PU-L-2) and waterborne polyacrylate emulsions with reactive emulsifiers (PA-1 and PA-2) show relatively good alcohol dilution stability. The composite resin emulsions (composite resins 5-8 in Table 2) blended with PA-2 showed little improvement in storage stability because the large particle size of the waterborne polyurethane microspheres prevented them from forming a Pickering emulsion structure with the waterborne polyacrylate microspheres. However, PU-S-1 and PU-S-2, with particle sizes of 20-50 nm, exhibited better dilution stability when blended with polyacrylate emulsions compared to the smaller particle size of PU-S-3. This may be because a suitable particle size blend can more effectively improve the difference in collision rate. This indicates that waterborne composite resin emulsions prepared by blending small-particle-size waterborne polyurethane emulsions and waterborne polyacrylate emulsions can improve the overall alcohol dilution storage stability of the resin emulsion. Therefore, waterborne composite resins blended with PU-S-1 and PA-1 were selected as a retort-resistant water-based ink binder suitable for high-speed printing, and the ratio of ketone-hydrazine groups will be further explored. Figure 1 In the images, ①, ②, and ③ are, in order, actual images of the small-particle-size waterborne polyurethane emulsion (PU-S-1), the waterborne polyacrylate emulsion without reactive emulsifier (PA-5), and the waterborne composite resin emulsion No. 1 in Table 2, after being diluted with 60wt% alcohol.

[0076] Table 3 shows the alcohol dilution stability test results of waterborne composite resin emulsions with different ketone-hydrazine ratios. As can be seen from Table 3, waterborne composite resins with different ratios all have good alcohol dilution stability.

[0077] Figure 2 The gel content (percentage of cross-linked portion in the total mass of the film) of the films prepared from different waterborne composite resin emulsions corresponding to serial numbers 1-8 in Table 2 is shown in the test results. Figure 2 It is known that only when an aqueous polyurethane emulsion containing hydrazide end-capsulation is compounded with an aqueous polyacrylate emulsion containing ketone carbonyl groups does the resulting composite resin have a high gel content. This indicates that a ketone hydrazide crosslinking reaction occurs during the drying and film-forming process, and the resulting film has a crosslinked network structure. Crosslinking cannot be achieved without either of them. Figure 3 Corresponding to the gel content test results of the films prepared from aqueous composite resin emulsions with different ketone-hydrazine ratios in Table 3, by Figure 3It can be seen that the gel content changes with the ratio of the two resins. When the optimal ratio of hydrazide group to ketone carbonyl group is 1:1, the gel content can reach up to about 90%, indicating that the waterborne composite resin has good room temperature self-crosslinking function and the degree of crosslinking can be controlled by the ratio of the two resins.

[0078] Figure 4 and Figure 5 The tensile strength test results and corresponding elongation at break test results of the films prepared with different resins in Table 3 are shown in the figure. It can be seen from the figure that the tensile strength at break of different films varies with different compounding ratios. When the ratio of hydrazide group to ketone carbonyl group is 1:1, the tensile strength of the film is the highest. However, their elongation at break is the opposite of the strength of the film. That is, the higher the tensile strength, the lower the elongation at break. This is because when the molar number of hydrazide groups in the waterborne composite resin is comparable to the molar number of ketone carbonyl groups, the degree of self-crosslinking reaction of the film is higher and the crosslinking density of the film is greater, resulting in higher tensile strength at break and relatively lower elongation at break.

[0079] Example 2:

[0080] A method for preparing a retort-resistant water-based ink binder suitable for high-speed printing. The preparation steps are as follows:

[0081] (1) Preparation of branched waterborne polyurethane emulsion:

[0082] Preparation of small-particle-size hydrazide-terminated branched waterborne polyurethane (PU-S-3): 100g of polyester glycol and 40g of isoflurane diisocyanate (IPDI) were added to a 1L three-necked flask and reacted at 80℃ and 200r / min for 3 hours. Then, the temperature was lowered to 60℃, and 20g of hydrophilic chain extender sodium ethylenediaminosulfonate (PPS), 4.5g of small-molecule chain extender 1,4-butanediol (BDO), 0.5g of glycerol, and 50g of acetone were added sequentially. The reaction was maintained at this temperature for another 4 hours. Subsequently, the system was cooled to below 40℃, the rotation speed was adjusted to 800r / min, and 300g of a deionized aqueous solution containing 4g of succinic dihydrazide (ADH) was added and emulsified for half an hour. Finally, the acetone was removed by vacuum distillation, yielding the small-particle-size hydrazide-terminated branched waterborne polyurethane (PU-S-3). The particle size of PU-S-3 was tested to be 40-50nm.

[0083] (2) The aqueous polyacrylate emulsion is prepared by the following steps: The preparation method is the same as that of the ketone carbonyl aqueous polyacrylate emulsion (PA-1) with reactive emulsifier in step (2) of Example 1.

[0084] (3) The above-prepared hydrazide-terminated branched waterborne polyurethane emulsion and waterborne polyacrylate emulsion were compounded according to the molar ratio of hydrazide group to ketone carbonyl group in their respective emulsions being 10:1, 5:1, 1:1, 1:5, and 1:10 to obtain different waterborne composite emulsions.

[0085] The resin emulsions obtained in steps (1), (2) and (3) were subjected to alcohol dilution stability tests; at the same time, the obtained resin was dried to form a film, and the film forming steps were the same as in implementation case 1. Subsequently, mechanical tensile and gel content tests were performed on different films.

[0086] Table 4. Alcohol dilution stability test of aqueous composite resin emulsions with different ketone-hydrazine ratios.

[0087]

[0088] As shown in Table 4, both the branched waterborne polyurethane emulsion (PU-S-3) and the waterborne composite resin emulsion have good alcohol dilution storage stability.

[0089] Figure 6 Table 4 shows the gel content test results for waterborne composite resin emulsions with different ketone-hydrazine ratios. The test results indicate that the gel content of the waterborne composite resin is higher than that of the individual waterborne polyurethane emulsion and waterborne polyacrylate emulsion; and the overall gel content is higher than that of the waterborne composite resin obtained in Example 1 by compounding linear hydrazine-terminated waterborne polyurethane emulsion and waterborne polyacrylate emulsion. Figure 3 This indicates that by designing the molecular chain structure of the waterborne polyurethane emulsion to be branched, that is, increasing the number of cross-linking reaction sites, the gel content of the waterborne composite resin film can be further improved.

[0090] Figure 7 and Figure 8 The tensile strength and elongation at break of the films prepared with different ketone-hydrazine ratios of waterborne composite resins are shown in Table 4. As can be seen from the figure, when the molar ratio of hydrazine groups to ketone carbonyl groups in the waterborne composite resin is closer to the ideal value of 1:1, the film obtained after drying has the highest tensile strength, while the elongation at break decreases accordingly. This is consistent with the results in Example 1. However, in this example, because the waterborne polyurethane molecular chain structure is branched, the waterborne composite resin obtained by compounding it with waterborne polyacrylate emulsion has a higher degree of crosslinking after drying, resulting in a relatively higher tensile strength for the film prepared with the waterborne composite resin in this example.

[0091] Example 3:

[0092] The aqueous composite resins numbered 2, 4, and 6 in Table 3 of Example 1 and the aqueous composite resins numbered 2, 4, and 6 in Table 4 of Example 2 were used to prepare water-based inks of different colors. The preparation steps are as follows: 15g of aqueous composite resin was added to a dispersion vessel, and the rotation speed was maintained at 600RPM. Then, 15g of color paste, 20g of ethanol, and 5g of purified water were added sequentially, and the mixture was stirred continuously for 30 minutes to obtain the water-based ink. Yellow, black, red, white, and blue inks were prepared using the same formulation. The water-based inks of different colors were allowed to stand and their storage stability was observed (judgment standard: storage at room temperature for more than 6 months is considered qualified). The color pastes for all colors were from Hangzhou Haivit Chemical Technology Co., Ltd., with batch numbers 220713-1 for yellow, 220713-1 for black, 220714-1 for red, 220719-1 for white, and 220629-1 for blue.

[0093] Table 5. Storage stability of water-based inks formulated with different water-based composite resins.

[0094]

[0095] As shown in Table 5, the water-based composite resins provided by this invention, when formulated with different colors, all exhibit storage stability exceeding 6 months, which can meet the usage cycle of normal warehouse storage, logistics transportation, and printing work.

[0096] Different colored water-based inks were applied to PET film using a printing machine. After drying and sealing, the film underwent a water resistance test. The test conditions were: steam pressure 120 kPa, temperature 125℃, maintained for 30 minutes. The inks on the PET film were then observed for deformation or fading to determine whether the film exhibited good water resistance.

[0097] Table 6. Resistant to boiling of different colored inks

[0098]

[0099] *Where × indicates poor resistance to boiling, √ indicates some resistance to boiling, and √√ indicates good resistance to boiling.

[0100] As shown in Table 6, the water-based inks formulated with resin No. 4 from Example 1 and resin No. 4 from Example 2 have relatively better water resistance. The water-based inks formulated with the other four resins also have good water resistance. This indicates that water-based inks of different colors formulated with different water-based composite resins, after being printed on PET film and dried and sealed, all have good water resistance.

Claims

1. A water-based printing vehicle for high-speed printing, which is resistant to retort, characterized in that, include: Aqueous polyurethane emulsion containing hydrazide groups and aqueous polyacrylate emulsion containing ketone carbonyl groups; the aqueous polyurethane emulsion has a particle size of 10-100 nm, a hydrazide functionality greater than or equal to 2, and exhibits alcohol dilution stability; the aqueous polyacrylate emulsion has a particle size of 100-300 nm; the molar ratio of hydrazide groups in the aqueous polyurethane emulsion to ketone carbonyl groups in the aqueous polyacrylate emulsion is between 10:1 and 1:

10.

2. The water-based ink binder resistant to boiling as described in claim 1, characterized in that, The particle size of the waterborne polyurethane emulsion is 20-50 nm; the particle size of the waterborne polyacrylate emulsion is 250-300 nm.

3. The water-based ink binder resistant to boiling as described in claim 1, characterized in that, The aqueous polyurethane emulsion containing hydrazide groups is an aqueous polyurethane emulsion with hydrazide groups at the end.

4. The water-based ink binder resistant to boiling as described in claim 3, characterized in that, A hydrazine-terminated aqueous polyurethane emulsion is prepared by the following method: Polyol, isocyanate, hydrophilic chain extender, small molecule chain extender, and salt-forming agent are reacted in acetone at 50-85℃ for 5-10 h to obtain an isocyanate-terminated polyurethane prepolymer. The temperature is then lowered to 30-70℃, and a multifunctional hydrazine monomer and deionized water are added for emulsification for 0.5-3 h. Acetone is then removed by vacuum distillation to obtain the hydrazine-terminated aqueous polyurethane emulsion. The proportions of the raw materials by mass are as follows: polyol: 10-60 parts; isocyanate: 10-60 parts; hydrophilic chain extender: 3-20 parts; small molecule chain extender: 3-20 parts; salt-forming agent: 2-16 parts; deionized water: 50-70 parts; acetone: 20-30 parts; hydrazine monomer: 5-15 parts.

5. The water-based ink binder resistant to boiling as described in claim 4, characterized in that, The polyol is one or more of polyester polyol, polycarbonate polyol, polyether polyol, organosilicon polyol, and polyacrylate polyol.

6. The water-based ink binder resistant to boiling as described in claim 4, characterized in that, The isocyanate is one or more selected from isophorone diisocyanate, 1,6-hexyl diisocyanate, dicyclohexylmethane diisocyanate, tetramethylcyclohexylmethane diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

7. The water-based ink binder resistant to boiling as described in claim 4, characterized in that, The hydrophilic chain extender is one or more of dimethylolpropionic acid, sodium ethylenediaminoethanesulfonate, diethylenetriamine, and methyldiethanolamine.

8. The water-based ink binder resistant to steaming and boiling according to claim 4, characterized in that, The small molecule chain extender is a multifunctional alcohol or amine compound, including one or more of 1,4-butanediol, ethylene glycol, methyl propylene glycol, 1,2-propanediol, glycerol, trimethylolpropane, octene glycol, 1,4-cyclohexanediethanolamine, ethylenediamine, dibutylamine, diethylenetriamine, and N-methyldiethanolamine.

9. The water-based ink binder resistant to boiling as described in claim 4, characterized in that, The salt-forming agent is one or more of triethylamine, ammonia, and N,N-dimethylisopropylamine.

10. The water-based ink binder resistant to boiling according to claim 4, characterized in that, The polyfunctional acylhydrazide monomer is one or more of adipic dihydrazide, sebacic dihydrazide, heptanic dihydrazide, octanoic dihydrazide, succinic dihydrazide, azelaic dihydrazide, and hexane dihydrazide.

11. A water-based ink suitable for high-speed printing, characterized in that, The water-based ink is obtained by diluting the heat-resistant binder and pigment according to any one of claims 1-10 with a diluent; the diluent contains alcohol.

Images