Water-based ink applied to pet film printing high adhesion and preparation method thereof

Abstract

The application relates to the technical field of water-based inks, in particular to a water-based ink with high adhesion for PET film printing and a preparation method thereof. The preparation method of the water-based ink with high adhesion for PET film printing comprises the following steps: S1, preparation of a water-based base ink; S2, preparation of a polyurethane prepolymer; S2, preparation of pre-emulsified acrylate monomers: methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and epoxy resin are mixed, an emulsifier, deionized water and an antioxidant are added, and pre-emulsification is carried out for 0.5-1 hours to form pre-emulsified acrylate monomers; S2, preparation of a composite emulsion; S3, preparation of the water-based ink; the water-based ink with high adhesion for PET film printing of the application is terminated with isocyanate, the polyurethane prepolymer is copolymerized with acrylate monomers and epoxy resin to form an interpenetrating network structure; and the water-based ink can directly form a strong combination on the PET surface, and the adhesion of the ink is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water-based ink, in particular to a water-based ink with high adhesion for PET film printing and a preparation method thereof. BACKGROUND

[0002] PET film is widely used in various packaging and industrial applications, especially in food, electronic product and pharmaceutical packaging. Due to its excellent physical properties such as heat resistance, chemical resistance and high transparency, PET film becomes the first choice material for many applications. However, how to ensure that the ink can be firmly attached to the surface of the PET film and not easily fall off or delaminate is a key problem that needs to be solved in the printing process.

[0003] Currently, printing with PET film as the substrate mainly uses lipid-soluble ink, and its solvent is usually ethyl acetate or toluene. The advantages of lipid-soluble ink compared to water-based ink mainly lie in the following aspects:

[0004] Strong adhesion: lipid-soluble ink can form a firm adhesion on the surface of PET film, as the surface of PET film is relatively smooth and has weak hydrophilicity, lipid-soluble ink can provide better adhesion effect through the volatilization of solvent and the interaction of ink components;

[0005] High composite firmness: the high composite firmness of lipid-soluble ink makes it more stable during the composite process and less likely to delaminate or delaminate;

[0006] Not easy to off-set: lipid-soluble ink is difficult to fall off from the surface due to its chemical properties, which is necessary for some high-demand applications (such as food and pharmaceutical packaging) to ensure that the product will not be contaminated during transportation and storage.

[0007] Many countries and regions are promoting the reduction of the use of harmful substances, especially those solvent-based inks that may have negative effects on the environment and human health. The solvents commonly used in lipid-soluble ink, such as toluene, xylene, etc., have greater harm to the environment and human body, especially the emission of volatile organic compounds (VOCs), which may affect air quality and worker health. Therefore, with the gradual strengthening of environmental protection regulations, water-based ink has become one of the alternatives.

[0008] Water-based ink is an ink with water as the solvent, compared to traditional solvent-based ink, water-based ink is more environmentally friendly, with very low VOC emissions, meeting modern environmental protection requirements. Therefore, many enterprises have begun to try to use water-based ink to replace traditional solvent-based ink, especially in some fields with strict environmental protection requirements, however, water-based ink still faces some challenges in printing and composite effect:

[0009] (1) Poor adhesion: due to the low surface energy of PET film, water-based ink is slightly worse than fat-soluble ink in adhesion, which leads to the adhesion of the printed layer being worse than that of fat-soluble ink, and easy peeling;

[0010] (2) Insufficient composite firmness: the composite firmness of water-based ink is often worse than that of fat-soluble ink, which will cause delamination between composite materials, affecting the performance and appearance of the final product;

[0011] (3) Slow drying speed: water-based ink usually needs longer time to dry completely, which increases the production cycle and equipment cost. SUMMARY

[0012] In view of the deficiencies of the prior art, the present application provides a water-based ink with high adhesion to PET substrate and a preparation method. The preparation method of the water-based ink with high adhesion for PET film printing comprises the following steps:

[0013] S1 Preparation of water-based base ink:

[0014] The pigment is mixed and ground with ethanol to obtain the base ink;

[0015] S2 Preparation of connecting material:

[0016] S210 Preparation of polyurethane prepolymer

[0017] S211: Put the polyol into the stirring reaction kettle, heat to 100-120℃, stir and vacuum, remove water;

[0018] S212: Reduce the temperature to 60-70℃, mix isocyanate with polyol, add catalyst and chain extender, react for 2-3h to prepare isocyanate-terminated polyurethane prepolymer;

[0019] S220 Preparation of pre-emulsified acrylic ester monomer

[0020] S221: Mix methyl methacrylate, butyl acrylate and hydroxyethyl acrylate with epoxy resin, add emulsifier, deionized water and antioxidant, pre-emulsify for 0.5-1h to form pre-emulsified acrylic ester monomer;

[0021] S230 Preparation of composite emulsion

[0022] S231: Mix the polyurethane prepolymer and the pre-emulsified acrylic ester monomer with deionized water and acetonitrile, heat to 70-80℃, add initiator dropwise, complete dropwise within 3h, then heat to 85-90℃, add crosslinking agent and react for 2-3h to ensure complete reaction;

[0023] S232: cooling to 40℃, adding neutralizing agent to neutralize, then adding pH regulator to adjust pH value to 8-9, adding adhesion promoter after filtration, stirring and mixing uniformly to prepare water-soluble acrylic acid-epoxy resin-polyurethane composite emulsion, i.e. connecting agent;

[0024] S3 Preparation of water-based ink:

[0025] Mixing the water-based base ink prepared in step S1 with the connecting agent prepared in S2 to prepare water-based ink.

[0026] Further, the polyol in step S211 is polyether polyol and / or polyester polyol, and the isocyanate in step S212 is isophorone diisocyanate or diphenylmethane diisocyanate.

[0027] Further, the catalyst is an organic tin catalyst, and the amount is 0.3-0.8% of the total mass of isocyanate and polyol;

[0028] The chain extender includes a hydrophilic chain extender and a small molecule chain extender, and the hydrophilic chain extender is dimethylol propanoic acid or dimethylol butanoic acid;

[0029] The small molecule chain extender is one or more of neopentyl glycol, methylpropanediol, ethylenediamine, and diethylenetriamine.

[0030] Further, the amount of the hydrophilic chain extender is 3-8% of the total mass of isocyanate and polyol;

[0031] The amount of the small molecule chain extender is 1-3% of the total mass of isocyanate and polyol.

[0032] Further, the mass ratio of methyl methacrylate, butyl acrylate, and hydroxyethyl acrylate in step S221 is (3-5):(4-6):1;

[0033] The amount of the emulsifier is 3-8% of the total mass of methyl methacrylate, butyl acrylate, and hydroxyethyl acrylate.

[0034] The amount of the emulsifier is 3-8% of the total mass of methyl methacrylate, butyl acrylate, and hydroxyethyl acrylate.

[0035] Further, the mass ratio of the sulfobetaine and 2-pyridyl thiourea is 1:(1-1.5).

[0036] Further, the mass ratio of the polyurethane prepolymer and the pre-emulsified acrylic monomer in step S231 is 1:(2-3).

[0037] The amount of the initiator is 0.5-0.8% of the mass of the pre-emulsified acrylic monomer.

[0038] The crosslinking agent is hydroxypropyl methacrylate and tetraethylene glycol dimethacrylate, and the amount is 2-5% of the mass of the pre-emulsified acrylic monomer.

[0039] Further, the mass ratio of the hydroxypropyl methacrylate and tetraethylene glycol dimethacrylate in step S231 is 1: (1-1.5).

[0040] Further, the neutralizing agent in step S232 is triethylamine, and the amount is 2-7% of the total mass of the polyurethane prepolymer and the pre-emulsified acrylic monomer.

[0041] The adhesion promoter is one or more of phosphate acrylate, titanate coupling agent, and phenoxydimethylsilane compound.

[0042] The amount of the adhesion promoter is 0.5-1% of the total mass of the polyurethane prepolymer and the pre-emulsified acrylic monomer.

[0043] In addition, the application also provides the water-based ink for PET film printing high adhesion prepared by the above preparation method.

[0044] Beneficial technical effects

[0045] (1) The water-based ink for PET film printing high adhesion of the application first prepares an isocyanate-terminated polyurethane prepolymer, and then copolymerizes with an acrylic monomer and an epoxy resin to form an interpenetrating network structure; the polyurethane segment provides flexibility and water resistance, the acrylic ester gives hardness and fast drying, and the epoxy resin enhances chemical bonding by reacting with the hydroxyl group on the PET surface through the epoxy group, so that the water-based ink can form strong bonding on the PET surface, and the adhesion of the ink is significantly improved.

[0046] (2) In the pre-emulsified acrylic monomer stage, the epoxy resin copolymerizes with the acrylic monomer, the epoxy group reacts with the ester group on the PET surface under alkaline conditions to form a stable ether bond covalent connection; the epoxy resin participates in the reaction in the emulsion copolymerization stage, rather than physical blending in the traditional process, to ensure that the epoxy group is uniformly distributed on the surface of the latex particle and directly contacts the PET interface, thereby improving the adhesion of the ink.

[0047] (3) The acrylic monomer is prepared by compounding methyl methacrylate, butyl acrylate, and hydroxyethyl acrylate; the hydroxyl group of the hydroxyethyl acrylate can form a hydrogen bond with the PET substrate to enhance the adhesion. Secondly, the hydroxyl group of the hydroxyethyl acrylate may participate in the crosslinking reaction in the emulsion polymerization process to improve the cohesive strength of the resin, thereby improving the adhesion.

[0048] (4) The hydrophilic chain extender is used in the application, carboxyl groups are introduced into the polyurethane prepolymer, the hydrophilicity and fluidity of the ink are improved by adjusting the segment structure, which helps to improve the wettability and dispersibility of the ink in the water-based system; the use of small molecule chain extender helps to enhance the crosslinking degree, so that the hardness and wear resistance of the ink are further enhanced;

[0049] (5) The emulsifier is compounded with sulfobetaine (zwitterionic) and 2-pyridyl thiourea (reactive), compared with the traditional SDS / OP-10 system, the dispersibility of the pigment in the water-based ink is further improved; sulfobetaine forms a directional adsorption layer at the ink-PET interface, reduces the interfacial tension, and makes the resin more easily spread and fill the surface defects of PET; 2-pyridyl thiourea is partially inserted into the polymer chain during polymerization, avoiding the weak boundary layer caused by the migration of traditional emulsifiers;

[0050] (6) Hydroxypropyl methacrylate is used with tetraethylene glycol dimethacrylate to form a three-dimensional crosslinked network through free radical polymerization, reducing the shrinkage stress in the film forming process, and the hydroxyl group of hydroxypropyl methacrylate forms a hydrogen bond to assist adhesion to the PET surface. DETAILED DESCRIPTION

[0051] The raw materials used in the examples and comparative examples of the application are as follows:

[0052] PTMEG-1000: polytetrahydrofuran, molecular weight 1000, hydroxyl value 110 mgKOH / g, manufacturer: Mitsubishi Chemical Corporation, Japan;

[0053] POL-456: polypropylene adipate, molecular weight 2000, hydroxyl value 56 mgKOH / g, manufacturer: Qingdao Xinyutaida Chemical Co., Ltd.;

[0054] MDI-50: diphenylmethane diisocyanate, manufacturer: Yantai Wanhua Polyurethane Co., Ltd.;

[0055] IPID: isophorone diisocyanate, manufacturer: Bayer, Germany;

[0056] T-12: dibutyltin dilaurate, manufacturer: Air Products and Chemicals, Inc., USA;

[0057] DMPA: dimethylol propionic acid, manufacturer: Shandong Saimeike Chemical Co., Ltd.;

[0058] DMBA: dimethylol butyric acid, manufacturer: Shandong Saimeike Chemical Co., Ltd.;

[0059] Neopentyl glycol: manufacturer: Zibo Anhao Chemical Co., Ltd.;

[0060] Methylpropanediol: manufacturer: Shandong Qiyi Chemical Technology Co., Ltd.

[0061] Ethylene diamine: manufacturer: Jinan Liyan Chemical Co., Ltd.

[0062] MMA: methyl methacrylate, manufacturer: Shandong Feihong New Material Co., Ltd.

[0063] BA: butyl acrylate, manufacturer: Shandong Feihong New Material Co., Ltd.

[0064] HEMA: hydroxyethyl acrylate, manufacturer: Shandong Feihong New Material Co., Ltd.

[0065] E-44: epoxy resin, manufacturer: Jinan Haiyuxing Chemical Co., Ltd.

[0066] Dodecyl ethoxy sulfobetaine: manufacturer: Shandong Chuangli New Material Co., Ltd.

[0067] 2-pyridyl thiourea: manufacturer: Shanghai Yuan Ye Biology;

[0068] p-benzenediol: manufacturer: Shanghai Yuan Ye Biology;

[0069] Ammonium persulfate: manufacturer: Shandong Youwei Chemical Co., Ltd.

[0070] HPMA: hydroxypropyl methacrylate, manufacturer: Shandong Hengqiang Chemical Co., Ltd.

[0071] Di-tetraethylene glycol dimethacrylate: manufacturer: Guangzhou Kangyang Chemical Co., Ltd.

[0072] Triethylamine: manufacturer: Shandong Feihong New Material Co., Ltd.

[0073] Phosphate acrylate: manufacturer: Jining Fangyi Chemical Co., Ltd.

[0074] Titanate coupling agent: manufacturer: Jinan Rongzheng Chemical Co., Ltd.

[0075] Methylphenyl diethoxysilane: manufacturer: Hubei Chengfeng Chemical Co., Ltd.

[0076] SDS: sodium dodecyl sulfate, manufacturer: Guangdong Guanghua Chemical Co., Ltd.

[0077] OP-10: manufacturer: Shanghai Lingfeng Chemical Reagent Co., Ltd.

[0078] Example 1

[0079] Preparation of S1 water-based base ink:

[0080] Into a dispersing vessel, 60 g of carbon black and 32 g of ethanol were added, and dispersed at a rotation speed of 1000 rpm for 60 min, and then the rotation speed was increased to 3000 rpm for dispersion and grinding for 4 h, and then left to stand for 30 min, and the base ink was discharged;

[0081] Preparation of S2 connecting material:

[0082] Preparation of S210 polyurethane prepolymer

[0083] S211: 50 g of PTMEG-1000 and 30 g of POL-456 were put into a three-necked flask for stirring and mixing, and the temperature was increased to 100-120 DEG C, and stirring and vacuum extraction were performed for 1-1.5 h to remove water;

[0084] S212: the temperature was decreased to 60-70 DEG C, 20 g of MDI-50 was added to the polyol for stirring and mixing, 0.4 g of catalyst T-12, 4 g of hydrophilic chain extender DMBA, and 2 g of small molecule chain extender ethylenediamine were added, and the reaction was performed for 2-3 h to prepare an isocyanate-terminated polyurethane prepolymer;

[0085] Preparation of S220 pre-emulsified acrylate monomer

[0086] S221: 30 g of MMA, 50 g of BA, 10 g of HEMA, and 4.5 g of E-44 were uniformly mixed and stirred, and then the temperature was increased to 80 DEG C, 0.9 g of dodecyl ethoxy sulfobetaine, 0.9 g of 2-pyridyl thiourea, 100 g of deionized water, and 1.5 g of hydroquinone were added, and pre-emulsification was performed for 0.5-1 h to form a pre-emulsified acrylate monomer;

[0087] Preparation of S230 composite emulsion

[0088] S231: 12 g of the polyurethane prepolymer prepared in step S212 and 28 g of the pre-emulsified acrylate monomer prepared in step S221 were mixed with 166 g of deionized water and 12 g of acetonitrile, and the temperature was increased to 80 DEG C, 4.6 g of an ammonium persulfate aqueous solution with a concentration of 3% was added dropwise, and the dropwise addition was completed within 3 h, and then the temperature was increased to 85-90 DEG C, 0.24 g of HPMA and 0.34 g of tetraethylene glycol dimethacrylate were added, and the reaction was performed for 2-3 h to ensure complete reaction;

[0089] S232: the temperature was decreased to 40 DEG C, 1.2 g of triethylamine was added for neutralization, and then ammonia water was added to adjust the pH value to 8, and then 0.2 g of phosphate acrylate was added after filtration, and the water-soluble acrylate-epoxy resin-polyurethane composite emulsion, i.e. the connecting material, was prepared after uniform stirring and mixing;

[0090] Preparation of S3 water-based ink:

[0091] The 46 g of water-based base ink prepared in step S1 was mixed with 154 g of the linking agent prepared in S232 to prepare a water-based ink.

[0092] Example 2

[0093] Preparation of the water-based base ink S1:

[0094] The 60 g of carbon black and 32 g of ethanol were added to a dispersion container, and dispersed at a speed of 1000 rpm for 60 min, and then the speed was increased to 3000 rpm for dispersion and grinding for 4 h, and then the mixture was left to stand for 30 min, and then the base ink was discharged;

[0095] Preparation of the linking agent S2:

[0096] Preparation of the polyurethane prepolymer S210

[0097] S211: 20 g of PTMEG-1000 and 50 g of POL-456 were placed in a three-necked flask and mixed by stirring, and the temperature was increased to 100-120°C, and the mixture was stirred and vacuumed for 1-1.5 h to remove water;

[0098] S212: the temperature was reduced to 60-70°C, 16 g of MDI-50 was added to the polyol and mixed by stirring, 0.6 g of catalyst T-12, 3 g of hydrophilic chain extender DMPA, 0.85 g of small molecule chain extender ethylenediamine, and 1 g of methylpropylene glycol were added, and the mixture was reacted for 2-3 h to prepare an isocyanate-terminated polyurethane prepolymer;

[0099] Preparation of the pre-emulsified acrylate monomer S220

[0100] S221: 40 g of MMA, 50 g of BA, 10 g of HEMA, and 6 g of E-44 were mixed and stirred uniformly, the temperature was increased to 80°C, 2 g of dodecyl ethoxy sulfobetaine, 3 g of 2-pyridyl thiourea, 100 g of deionized water, 7.5 g of acetonitrile, and 1.5 g of hydroquinone were added, and the mixture was pre-emulsified for 0.5-1 h to form a pre-emulsified acrylate monomer;

[0101] Preparation of the composite emulsion S230

[0102] S231: 12 g of the polyurethane prepolymer prepared in step S212 and 36 g of the pre-emulsified acrylate monomer prepared in step S221 were mixed with 165 g of deionized water and 16 g of acetonitrile, and the temperature was increased to 80°C, 9.6 g of ammonium persulfate aqueous solution with a concentration of 3% was added dropwise, and the addition was completed within 3 h, and then the temperature was increased to 85-90°C, 0.72 g of HPMA and 0.72 g of tetraethylene glycol dimethacrylate were added, and the mixture was reacted for 2-3 h to ensure complete reaction;

[0103] S232: cooling to 40℃, adding 2g of triethylamine to neutralize, then adding ammonia water to adjust the pH value to 8.5, after filtration, adding 0.38g of titanate coupling agent, stirring and mixing uniformly to prepare a water-soluble acrylic acid-epoxy resin-polyurethane composite emulsion, i.e. the connecting agent;

[0104] S3 Preparation of water-based ink:

[0105] After mixing 55g of the water-based base ink prepared in step S1 with 145g of the connecting agent prepared in S232 at a rotation speed of 1000 rpm, a water-based ink is prepared.

[0106] Example 3

[0107] S1 Preparation of water-based base ink:

[0108] After adding 60g of carbon black and 32g of ethanol into a dispersion container, dispersing at a rotation speed of 1000 rpm for 60min, increasing the rotation speed to 3000 rpm for dispersion and grinding for 4h, and standing for 30min, the base ink is obtained by discharging;

[0109] S2 Preparation of connecting agent:

[0110] S210 Preparation of polyurethane prepolymer

[0111] S211: Put 10g of PTMEG-1000 and 70g of POL-456 into a three-necked flask for stirring and mixing, heat to 100-120℃, stir and vacuum for 1-1.5h to remove moisture;

[0112] S212: Reduce the temperature to 60-70℃, add 15g of IPDI to the polyol for stirring and mixing, add 0.7g of catalyst T-12, 7g of hydrophilic chain extender DMPA, 1g of small molecule chain extender ethylenediamine, and react for 2-3h to prepare an isocyanate-terminated polyurethane prepolymer;

[0113] S220 Preparation of pre-emulsified acrylic ester monomer

[0114] S221: After mixing and stirring 40g of MMA, 60g of BA, 10g of HEMA and 8g of E-44 uniformly, heat to 80℃, add 0.9g of dodecyl ethoxy sulfobetaine, 1.35g of 2-pyridyl thiourea and 120g of deionized water and 1.5g of hydroquinone, pre-emulsify for 0.5-1h to form a pre-emulsified acrylic ester monomer;

[0115] S230 Preparation of composite emulsion

[0116] S231: 12 g of the polyurethane prepolymer prepared in step S212 was mixed with 24 g of the pre-emulsified acrylate monomer prepared in step S221, 168 g of deionized water, and 12 g of acetonitrile, and the mixture was warmed to 80°C. 4.8 g of an ammonium persulfate aqueous solution having a concentration of 3% was added dropwise, and the dropwise addition was completed within 3 h. Then, the temperature was raised to 85-90°C, and 0.48 g of HPMA and 0.72 g of tetraethylene glycol dimethacrylate were added, and the reaction was carried out for 2-3 h to ensure that the reaction was complete.

[0117] S232: The temperature was lowered to 40°C, and 2.2 g of triethylamine was added for neutralization. Then, ammonia water was added to adjust the pH value to 9. After filtration, 0.28 g of phosphate acrylate was added, and the mixture was stirred and uniformly mixed to prepare a water-soluble acryl-epoxy-polyurethane composite emulsion, i.e., a connecting agent.

[0118] S3 Preparation of the water-based ink:

[0119] After the 50 g of the water-based base ink prepared in step S1 and the 150 g of the connecting agent prepared in S232 were uniformly mixed at a rotation speed of 1000 rpm, a water-based ink was prepared.

[0120] Example 4

[0121] S1 Preparation of the water-based base ink:

[0122] After 60 g of carbon black and 32 g of ethanol were added to a dispersion container and dispersed at a rotation speed of 1000 rpm for 60 min, the rotation speed was increased to 3000 rpm, and dispersion milling was performed for 4 h. After standing for 30 min, the base ink was discharged.

[0123] S2 Preparation of the connecting agent:

[0124] S210 Preparation of the polyurethane prepolymer

[0125] S211: 100 g of POL-456 was placed in a three-necked flask and stirred and mixed. The temperature was raised to 100-120°C, and stirring and vacuuming were performed for 1-1.5 h to remove moisture.

[0126] S212: The temperature was lowered to 60-70°C, and 18 g of IPID was added to the polyol and stirred and mixed. 0.7 g of a catalyst T-12, 8 g of a hydrophilic chain extender DMPA, 1 g of a small molecule chain extender ethylenediamine, and 1 g of neopentyl glycol were added, and the reaction was carried out for 2-3 h to prepare an isocyanate-terminated polyurethane prepolymer.

[0127] S220 Preparation of the pre-emulsified acrylate monomer

[0128] S221: 40 g of MMA, 50 g of BA, 10 g of HEMA, and 8 g of E-44 were mixed and stirred uniformly, and then heated to 80°C. 2 g of dodecyl ethoxy sulfobetaine, 2 g of 2-pyridyl thiourea, 100 g of deionized water, 7.5 g of acetonitrile, and 1.5 g of hydroquinone were added, and pre-emulsification was performed for 0.5-1 h to form a pre-emulsified acrylate monomer;

[0129] S230 Preparation of the composite emulsion

[0130] S231: 12 g of the polyurethane prepolymer prepared in step S212 was mixed with 30 g of the pre-emulsified acrylate monomer prepared in step S221, 165 g of deionized water, and 12 g of acetonitrile, and then heated to 80°C. 5.25 g of an ammonium persulfate aqueous solution having a concentration of 3% was added dropwise, and the dropwise addition was completed within 3 h. Then, the temperature was increased to 85-90°C, 0.4 g of HPMA and 0.5 g of tetraethylene glycol dimethacrylate were added, and the reaction was performed for 2-3 h to ensure complete reaction.

[0131] S232: The temperature was decreased to 40°C, 0.9 g of triethylamine was added for neutralization, and then ammonia water was added to adjust the pH value to 8.4. After filtration, 0.125 g of phosphate acrylate and 0.175 g of methyl phenyl diethoxy silane were added and stirred to obtain a water-soluble acrylate-epoxy resin-polyurethane composite emulsion, which was a connecting agent.

[0132] S3 Preparation of the water-based ink:

[0133] The 50 g of the water-based base ink prepared in step S1 was mixed with 150 g of the connecting agent prepared in S232 at a rotation speed of 1000 rpm to obtain a water-based ink.

[0134] Comparative Example 1

[0135] The difference between this comparative example and Example 2 is that the preparation of the composite emulsion in step S230 is different, and the specific steps are as follows:

[0136] S231: 24 g of the polyurethane prepolymer prepared in step S212 was mixed with 24 g of the pre-emulsified acrylate monomer prepared in step S221, 165 g of deionized water, and 16 g of acetonitrile, and then heated to 80°C. 6.4 g of an ammonium persulfate aqueous solution having a concentration of 3% was added dropwise, and the dropwise addition was completed within 3 h. Then, the temperature was increased to 85-90°C, 0.48 g of HPMA and 0.48 g of tetraethylene glycol dimethacrylate were added, and the reaction was performed for 2-3 h to ensure complete reaction.

[0137] S232: The temperature was decreased to 40°C, 2 g of triethylamine was added for neutralization, and then ammonia water was added to adjust the pH value to 8.5. After filtration, 0.38 g of a titanate coupling agent was added and stirred to obtain a water-soluble acrylate-epoxy resin-polyurethane composite emulsion, which was a connecting agent.

[0138] Comparative Example 2

[0139] The difference between this comparative example and Example 2 is that no epoxy resin E-44 is added in step S221.

[0140] Comparative Example 3

[0141] The difference between this comparative example and Example 2 is that the amount of epoxy resin E-44 used in step S221 is 15 g.

[0142] Comparative Example 4

[0143] The difference between this comparative example and Example 2 is that no dodecyl ethyloxy sulfobetaine is added in step S221, and an equivalent amount of 2-pyridyl thiourea is used instead.

[0144] Comparative Example 5

[0145] The difference between this comparative example and Example 2 is that no 2-pyridyl thiourea is added in step S221, and an equivalent amount of dodecyl ethyloxy sulfobetaine is used instead.

[0146] Comparative Example 6

[0147] The difference between this comparative example and Example 2 is that the SDS / OP-10 system emulsifying system is used instead of dodecyl ethyloxy sulfobetaine and 2-pyridyl thiourea in step S221, and the amount of OP-10 used is 3 g, and the amount of SDS used is 2 g.

[0148] Comparative Example 7

[0149] The difference between this comparative example and Example 2 is that the amount of dodecyl ethyloxy sulfobetaine used in step S221 is 3 g, and the amount of 2-pyridyl thiourea used is 2 g.

[0150] Comparative Example 8

[0151] The difference between this comparative example and Example 2 is that no HPMA is added in step S231, and an equivalent amount of tetraethylene glycol dimethacrylate is used instead.

[0152] Comparative Example 9

[0153] The difference between this comparative example and Example 2 is that no tetraethylene glycol dimethacrylate is added in step S231, and an equivalent amount of HPMA is used instead.

[0154] Comparative Example 10

[0155] The difference between this comparative example and Example 2 is that no small molecule chain extender ethylenediamine, neopentyl glycol is added in step S212, and an equivalent amount of hydrophilic chain extender DMPA is used instead.

[0156] Comparative Example 11

[0157] The difference between this comparative example and Example 2 is that the pre-emulsified acrylate monomer is replaced by a solution of acrylic resin Soluryl-60L produced by Hanhwa, Korea.

[0158] Preparation of the acrylic resin Soluryl-60L solution:

[0159] 100 g of solid acrylic resin Soluryl-60L was added to 100 g of deionized water, and after being heated to 70°C, 7 g of 25% ammonia was slowly added, and stirred at 75-80°C for 2 h to obtain the acrylic resin Soluryl-60L solution.

[0160] Comparative Example 12

[0161] The difference between this comparative example and Example 2 is that HEMA is not used in step S221, and an equal amount of BA is used instead.

[0162] (1) Ink adhesion test

[0163] Preparation of the ink layer: The ink prepared in each example and comparative example was subjected to gravure printing. Among them, the plastic gravure electrographic plate has a line number of 90 and a depth of 25-30 μm; the length of the air box is 2.5 m, the air speed of the air box is 30-35 m / s, and the printing speed is 600 m / min on a PET film.

[0164] According to GB / T13217.7-2023, the disc peeling method was used for testing, the adhesive tape was pasted on the ink printed surface, and the tape was rolled back and forth 3 times on the tape press, then the sample was immediately clamped on the A disc. The exposed tape was fixed on the B disc, and then the machine was started, and the A disc was rotated at a speed of 0.6 m / s to peel off the tape.

[0165] A semi-transparent millimeter grid paper with a width of 20 mm was overlaid on the peeled part, and the number of grids occupied by the ink layer and the number of grids occupied by the peeled ink layer were counted respectively, and calculated according to the following formula:

[0166] ;

[0167] A is the ink adhesion, A1 is the number of grids of the ink layer remaining on the substrate after the tape is peeled off, and A2 is the number of grids of the peeled ink layer.

[0168] The ink adhesion test results of Examples 1-4 and Comparative Examples 1-12 are shown in Table 1.

[0169] Table 1:

[0170] Adhesion (%) Example 1 99.4 Example 2 99.6 Example 3 99.3 Example 4 99.4 Comparative Example 1 97.2 Comparative Example 2 97.7 Comparative Example 3 98.3 Comparative Example 4 97.1 Comparative Example 5 97.0 Comparative Example 6 97.4 Comparative Example 7 97.3 Comparative Example 8 96.8 Comparative Example 9 96.6 Comparative Example 10 95.9 Comparative Example 11 92.2 Comparative Example 11 91.5

[0171] (2) Ink resistance to ethanol, alkali, acid, and water

[0172] A small amount of the ink prepared in each example and comparative example was placed on the top of a sample paper with a doctor blade, and the sample paper was scraped with the doctor blade from top to bottom, to form a uniform sample, which was then placed at room temperature for 24 hours to dry;

[0173] The color of the sample was observed and compared with the sample without soaking, and the acid, alkali, alcohol and water resistance of the sample was evaluated according to Table 2.

[0174] After soaking for 24 hours, the sample was taken out with tweezers, and the color change of the sample was observed and compared with the sample without soaking, and the acid, alkali, alcohol and water resistance of the sample was evaluated according to Table 2.

[0175] Table 2:

[0176] Grade Degree of scratch discoloration 1 Severe discoloration 2 Obvious discoloration 3 Slight discoloration 4 Essentially no discoloration 5 No discoloration

[0177] The test results are shown in Table 3.

[0178] Table 3

[0179] Ethanol resistance, alkali resistance, acid resistance, water resistance Example 1 Grade 5 Example 2 Grade 5 Example 3 Grade 5 Example 4 Grade 5 Comparative Example 1 Grade 5 Comparative Example 2 Grade 3 Comparative Example 3 Grade 4 Comparative Example 4 Grade 3 Comparative Example 5 Grade 3 Comparative Example 6 Grade 4 Comparative Example 7 Grade 4 Comparative Example 8 Grade 3 Comparative Example 9 Grade 3 Comparative Example 10 Grade 3 Comparative Example 11 Grade 3 Comparative Example 12 Grade 3

[0180] According to the above test results, it can be concluded that the water-based ink for printing PET film with high adhesion of the application has high adhesion to PET film, and has strong resistance to ethanol, alkali, acid and water.

[0181] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the specification. The specification selects and describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application.

Claims

1. A method for preparing water-based ink for printing on PET film with high adhesion, characterized in that, The method comprises the following steps: S1: Preparation of an aqueous base ink The base ink is obtained by mixing and grinding pigments with ethanol; S2: Preparation of a connecting agent S210: Preparation of a polyurethane prepolymer S211: Put the polyol into a stirring reaction kettle, heat to 100-120 DEG C, stir and vacuumize to remove water; S212: Reduce the temperature to 60-70 DEG C, mix the isocyanate with the polyol, add a catalyst and a chain extender, and react for 2-3 hours to obtain an isocyanate-terminated polyurethane prepolymer; The chain extender comprises a hydrophilic chain extender and a small molecule chain extender, and the hydrophilic chain extender is dimethylol propionic acid or dimethylol butyric acid; The small molecule chain extender is one or more of neopentyl glycol, methyl propylene glycol, ethylenediamine and diethylenetriamine; S220: Preparation of a pre-emulsified acrylate monomer S221: Mix methyl methacrylate, butyl acrylate and hydroxyethyl acrylate with an epoxy resin, add an emulsifier and deionized water and an antioxidant, pre-emulsify for 0.5-1 hour to form a pre-emulsified acrylate monomer; The epoxy resin is 3-8% of the total mass of the methyl methacrylate, butyl acrylate and hydroxyethyl acrylate; The mass ratio of the methyl methacrylate, butyl acrylate and hydroxyethyl acrylate is (3-5):(4-6):1; The emulsifier is sulfobetaine and 2-pyridyl thiourea, and the amount is 3-8% of the total mass of the methyl methacrylate, butyl acrylate and hydroxyethyl acrylate, and the mass ratio of the sulfobetaine and 2-pyridyl thiourea is 1:(1-1.5); S230: Preparation of a composite emulsion S231: Mix the polyurethane prepolymer and the pre-emulsified acrylate monomer with deionized water and acetonitrile, heat to 70-80 DEG C, add an initiator dropwise, complete the dropwise addition within 3 hours, then heat to 85-90 DEG C, add a crosslinking agent and react for 2-3 hours to ensure complete reaction; The mass ratio of the polyurethane prepolymer and the pre-emulsified acrylate monomer is 1:(2-3); The crosslinking agent is hydroxypropyl methacrylate and tetraethylene glycol dimethacrylate, and the amount is 2-5% of the mass of the pre-emulsified acrylate monomer; The mass ratio of the hydroxypropyl methacrylate and tetraethylene glycol dimethacrylate is 1:(1-1.5); S232: Reduce the temperature to 40 DEG C, add a neutralizing agent to neutralize, then add a pH adjuster to adjust the pH value to 8-9, filter, add an adhesion promoter, mix uniformly and obtain a water-soluble acrylate-epoxy resin-polyurethane composite emulsion, i.e. a connecting agent; S3: Preparation of an aqueous ink Mix the aqueous base ink prepared in step S1 with the connecting agent prepared in step S2 to obtain an aqueous ink.

2. The method for preparing water-based ink with high adhesion for printing on PET film according to claim 1, characterized in that, The polyol in step S211 is a polyether polyol and / or a polyester polyol, and the isocyanate in step S212 is isophorone diisocyanate or diphenylmethane diisocyanate.

3. The method for preparing water-based ink with high adhesion for printing on PET film according to claim 2, characterized in that, The catalyst is an organic tin catalyst, and the amount is 0.3-0.8% of the total mass of the isocyanate and the polyol.

4. The method for preparing water-based ink with high adhesion for printing on PET film according to claim 3, characterized in that, The amount of the hydrophilic chain extender is 3-8% of the total mass of the isocyanate and the polyol. The amount of the small molecule chain extender is 1-3% of the total mass of the isocyanate and the polyol.

5. The preparation method of the water-based ink with high adhesion for printing PET film according to claim 1, characterized in that: the initiator is ammonium persulfate, and the amount is 0.5-0.8% of the mass of the pre-emulsified acrylate monomer.

6. The method for preparing water-based ink with high adhesion for printing on PET film according to claim 1, characterized in that, the neutralizing agent in step S232 is triethylamine, and the amount is 2-7% of the total mass of the polyurethane prepolymer and the pre-emulsified acrylate monomer; the adhesion promoter is one or more of phosphate acrylate, titanate coupling agent, and phenoxydimethylsilane compound; the amount of the adhesion promoter is 0.5-1% of the total mass of the polyurethane prepolymer and the pre-emulsified acrylate monomer.

7. A water-based ink for printing on a PET film with high adhesion, characterized by, The water-based ink with high adhesion for printing PET film is prepared according to the preparation method of the water-based ink with high adhesion for printing PET film of any one of claims 1-6.