An environment-friendly black ink and its preparation process

Abstract

This application relates to the technical field of inks, and specifically discloses an environmentally friendly black ink and its preparation process. The raw materials used in an environmentally friendly black ink include the following components in weight percentages: binder 50-55 wt%; dispersant 1.5-2 wt%; colorant 10-15 wt%; filler 3-5 wt%; solvent 20-25 wt%; the balance is other additives; the dispersant is M w a block copolymer with = 11500-12600, and the binder is modified waterborne polyurethane; its preparation method is: premix the dispersant, colorant, filler, solvent and half of the additives evenly, then add the binder, grind, and then add the remaining half of the additives and mix evenly to finally obtain the environmentally friendly black ink. The ink layer formed after spraying and curing the product of this application has an adhesion fastness of up to grade II or above, a glossiness of up to 82.6% or above, and the maximum number of friction times under a load of 200 g can reach 138 times or above.

Description

Technical Field

[0001] This application relates to the technical field of inks, and particularly to an environmentally friendly black ink and its preparation process. Background Art

[0002] Ink is an indispensable material in the printing industry, used to transfer information such as patterns and texts onto printing substrates through printing or spraying methods. The composition of ink mainly includes components such as colorants, binders, fillers, and additives. These components are uniformly mixed and repeatedly rolled to form a viscous colloidal fluid. The performance and quality of ink directly affect the appearance, durability, and environmental friendliness of printed products. Currently, common ink types mainly include solvent-based inks, water-based inks, UV inks, and solid inks.

[0003] Among them, water-based ink is an ink prepared with water-based resin as the binder, containing almost no volatile organic compounds, having relatively low harm to the environment and human health, having a certain environmental protection significance, and being applicable to various printing methods. Therefore, water-based ink, as an environmentally friendly, safe, and efficient printing ink, has a wide application range and excellent performance, and is an important driving force for the printing industry to transform towards green manufacturing.

[0004] Currently, the most commonly used colorant is carbon black, which has good durability, wear resistance, environmental friendliness, and covering power, and has a relatively low price. A small amount can achieve an ideal coloring effect. However, when carbon black is combined with water-based ink, new problems are found. It is difficult for the water-based binder in water-based ink to fully disperse carbon black, and carbon black will agglomerate to varying degrees in the system. To avoid the decrease in the smoothness of the ink layer and the damage to durability (the reduction of friction resistance and adhesion ability) caused by agglomeration, the amount of carbon black has to be reduced at this time, but this will seriously affect the gloss of water-based ink and greatly reduce its appearance quality. Summary of the Invention

[0005] To solve the above technical problems, this application provides an environmentally friendly black ink and its preparation process.

[0006] In a first aspect, this application provides an environmentally friendly black ink. The raw materials used include the following components in weight percentages: binder 50 - 55wt%; dispersant 1.5 - 2wt%; colorant 10 - 15wt%; filler 3 - 5wt%; solvent 20 - 25wt%; the balance is other additives; the dispersant is M wA block copolymer with a value of 11500 - 12600, and the binder is a modified waterborne polyurethane, which is prepared by the following method: I. Transesterify the PET material under the condition of adding a catalyst to form a capped PET oligomer; II. Mix 2-hydroxyethyl disulfide, PET oligomer, ethylene oxide-propylene oxide copolymer, and isophorone diisocyanate with a weight ratio of (1.5 - 3):(0.6 - 2.5):20:11, add a catalyst, and react to obtain the binder.

[0007] By adopting the above technical solution, in this application, the waste PET material is first subjected to transesterification reaction under the condition of a catalyst to obtain a PET oligomer capped with neopentyl glycol (NPG) and dipropylene glycol (DPG). Subsequently, a waterborne polyurethane is prepared by using an ethylene oxide-propylene oxide copolymer and isophorone diisocyanate. Then, 2-hydroxyethyl disulfide and the PET oligomer are added to optimize the light transmittance of the waterborne polyurethane. And in this application, the addition amounts of 2-hydroxyethyl disulfide and the PET oligomer are strictly controlled. If the addition amount of 2-hydroxyethyl disulfide and / or the PET oligomer is too large, the light transmittance will decrease instead of increase. If the addition amount is too small, the effects of effectively improving the light transmittance and water resistance cannot be achieved. Finally, the obtained binder has a light transmittance of not less than 95.2% in the wavelength range of 400 - 800 nm, having a high light transmittance.

[0008] On this basis, this application also reduces the addition amount of the colorant (carbon black), thereby reducing the agglomeration degree of carbon black in the system, and also adds an acrylic block copolymer as a dispersant. This dispersant can have an affinity anchoring effect with carbon black and fully improve the dispersion efficiency of carbon black in the system by using its own hydrophilic chain segments, further reducing the possibility of carbon black agglomeration in the system, thereby significantly improving the internal uniformity of the ink system, and then improving the gloss, adhesion strength, and abrasion resistance of the ink layer formed after printing. Further, this application controls the average molecular weight M of the acrylic block copolymer w , making its dispersion effect better. If the average molecular weight is too large, the dispersant itself will have entanglement and folding phenomena, affecting its dispersion effect in the system, and the hydrophilic chain segments will also have an excessive association effect with water, thereby weakening its dispersion assistance effect on carbon black; if the average molecular weight is too small, the anchoring efficiency between the dispersant and carbon black is insufficient, and a good dispersion effect cannot be achieved either.

[0009] Generally speaking, this application has fully improved the agglomeration phenomenon of carbon black from two aspects: reducing the carbon black dosage and enhancing the carbon black dispersion effect. Moreover, the binder with high transparency of this application can ensure that the ink still has high gloss even when the carbon black dosage is reduced, with excellent appearance quality. The finally obtained environmentally friendly black ink combines environmental friendliness, durability, and high gloss. Experimental data shows that the adhesion fastness rating of the environmentally friendly black ink of this application can reach level II or above, the gloss can reach more than 82.6%, and the maximum number of friction times under a 200g load can reach 138 times or above.

[0010] Preferably, in the step II, the weight ratio of 2-hydroxyethyl disulfide, PET oligomer, ethylene oxide-propylene oxide copolymer, and isophorone diisocyanate is 2.31:1.24:20:11.

[0011] By adopting the above technical solution, this application further controls the weight ratio of 2-hydroxyethyl disulfide, PET oligomer, ethylene oxide-propylene oxide copolymer, and isophorone diisocyanate, thereby further improving the light transmittance and water resistance of the binder. Experimental data proves that when the weight ratio is 2.31:1.24:20:11, the light transmittance of the binder in the wavelength range of 400 - 800nm can reach more than 96.1%, and the water resistance of the finally prepared ink can reach level I.

[0012] Preferably, the dispersant is prepared by the following method: Mix methacrylic acid, dimethylaminoethyl methacrylate, and allyl polyoxyethylene ether according to a molar ratio of (1 - 2):1:(1 - 2), and react under the protection of inert gas and in the presence of a catalyst. Cool to room temperature, adjust the pH to neutral, and obtain a dispersant with M w = 11500 - 12600 after distillation.

[0013] By adopting the above technical solution, this application forms a block copolymer from methacrylic acid, dimethylaminoethyl methacrylate, and allyl polyoxyethylene ether under certain conditions. This block copolymer has both hydrophilic and hydrophobic segments, which can improve the carbon black dispersibility and make the system have a certain degree of hydrophobicity at the same time. The finally obtained ink can have good internal uniformity and water resistance after spraying and curing.

[0014] Preferably, the allyl polyoxyethylene ether is APEG-500.

[0015] By adopting the above technical solution, in allyl polyoxyethylene ethers with different degrees of polymerization, APEG-500 is used as the hydrophilic monomer in the dispersant in the present application. It has been proven by experiments that under the average molecular weight and molar ratio of materials controlled in the present application, APEG-500 has a more suitable degree of polymerization than allyl polyoxyethylene ethers with other degrees of polymerization, and thus has a more suitable chain length of the hydrophilic segment, which can further balance the effect of the dispersant on anchoring carbon black and its own dispersing effect, and can make the ink have more excellent wear resistance after spraying and curing.

[0016] Preferably, the molar ratio of methacrylic acid, dimethylaminoethyl methacrylate and allyl polyoxyethylene ether is 1.5:1:1.5.

[0017] By adopting the above technical solution, on the basis of using APEG-500 as allyl polyoxyethylene ether, the present application further controls the molar ratio of methacrylic acid, dimethylaminoethyl methacrylate and allyl polyoxyethylene ether to be 1.5:1:1.5, thereby optimizing the balance of the internal uniformity and water resistance of the ink. By strictly controlling the amounts of methacrylic acid and allyl polyoxyethylene ether, the ratio of the hydrophilic segment to the hydrophobic segment of the dispersant is controlled. The appropriate hydrophilic segment can effectively improve the dispersing effect of carbon black and minimize its own aggregation degree in the aqueous system, and the appropriate hydrophobic segment can improve the water resistance of the ink and avoid the competitive association of itself in the aqueous system as much as possible, maintaining the water-oil balance of the ink. After testing, the water resistance grade of the ink of the present application can reach the I-level standard.

[0018] Preferably, the M w of the dispersant is 12200.

[0019] By adopting the above technical solution, during the reaction in the present application, the molecular weight of the product of the dispersant is continuously monitored, and through quenching reaction, the average molecular weight of the finally obtained dispersant is controlled, balancing the degree of assistance of the dispersant in dispersing carbon black and its own dispersing degree. Experimental data shows that when the average molecular weight is controlled at 12200 in the present application, the dispersant can make the dispersing effects of itself and carbon black reach the best level, and the adhesion fastness, wear resistance and glossiness are improved.

[0020] Preferably, the raw materials used include the following components by weight percentage: binder 54wt%; dispersant 1.75wt%; colorant 12wt%; filler 4wt%; solvent 24wt%; and the balance is other additives.

[0021] In the second aspect, the present application provides a preparation process of an environmentally friendly black ink, including the following steps: premixing the dispersant, colorant, filler, solvent and half of the additives evenly and then adding the binder, grinding, and then adding the remaining half of the additives and mixing evenly to finally obtain the environmentally friendly black ink.

[0022] In summary, the present application has the following beneficial technical effects:

[0023] 1. The present application has fully improved the agglomeration phenomenon of carbon black from two aspects: reducing the carbon black dosage and enhancing the carbon black dispersion effect. Moreover, the high-transparency binder of the present application enables the ink to still have a high glossiness under the condition of reduced carbon black dosage, with excellent appearance quality. The finally obtained environmentally friendly black ink combines environmental friendliness, durability, and high glossiness. Experimental data shows that the adhesion fastness rating of the environmentally friendly black ink of the present application can reach Grade II or above, and the glossiness can reach more than 82.6%;

[0024] 2. The present application strictly controls the ratio of the hydrophilic segment to the hydrophobic segment in the dispersant, the average molecular weight of the dispersant, and the degree of polymerization of allyl polyoxyethylene ether, so that the finally obtained ink can have good internal uniformity and water resistance after spraying and curing;

[0025] 3. The present application strictly controls the addition amounts of 2-hydroxyethyl disulfide and PET oligomer in the preparation process of the binder, synchronously improving the light transmittance and water resistance of the binder, so that the finally obtained ink also has good water resistance and high glossiness. Detailed implementation manners

[0026] Sources of materials

[0027] Unless otherwise specified, the raw materials used in the present application are all commercially available products, specifically:

[0028] Titanium butoxide is purchased from Shandong Jibei New Materials Co., Ltd;

[0029] 2-Hydroxyethyl disulfide is from Shandong Xiya Chemical;

[0030] The ethylene oxide-propylene oxide copolymer is purchased from Sigma-Aldrich, with the CAS number 9003-11-6 and an average molecular weight of 5800. It is placed in a vacuum drying oven at 0.8 MPa and 110 °C for 2 h before use to complete preliminary drying and is reserved for use;

[0031] Polytetrahydrofuran is purchased from Hubei Shineng Chemical Technology Co., Ltd, with the model PTMEG-2000. It is placed in a vacuum drying oven at 0.8 MPa and 110 °C for 2 h before use to complete preliminary drying and is reserved for use;

[0032] The tetrahydrofuran-ethylene oxide polymer is purchased from Kinbester Co., Ltd, with the CAS number 27637-03-2. It is placed in a vacuum drying oven at 0.8 MPa and 110 °C for 2 h before use to complete preliminary drying and is reserved for use;

[0033] Boron trifluoride diethyl etherate, propylene oxide, tetrahydrofuran, and 1,2-propanediol were all purchased from Sinopharm Chemical Reagent Co., Ltd., of analytical purity;

[0034] Isophorone diisocyanate was purchased from Anhui Jinyueguan New Material Technology Co., Ltd.;

[0035] Dibutyltin dilaurate was purchased from Jinan Hongboli Chemical Co., Ltd.;

[0036] Methacrylic acid was purchased from Sinopharm Group Co., Ltd.;

[0037] Isopropanol was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd.;

[0038] n-Dodecyl mercaptan was purchased from Chevron Phillips Chemical Company;

[0039] Azobisisobutyronitrile was purchased from Sinopharm Group Co., Ltd.;

[0040] Dimethylaminoethyl methacrylate was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., of analytical purity;

[0041] APEG-300, APEG-500, and APEG-700 were all custom-made by Jiangsu Haian Petrochemical Factory, with an active ingredient content of 99 wt%;

[0042] Hydrophilic titanium dioxide was purchased from Jiangsu River and Sea Nano Technology Co., Ltd., with the model number NY-010A;

[0043] Carbon black was purchased from Tianjin Baochi Chemical Technology Co., Ltd., with D50 of 8 um and a carbon content of ≥99.9 wt%;

[0044] The wetting agent was purchased from Hangzhou Lin'an Digao Organic Chemistry Co., Ltd., with the model number TEGO-245;

[0045] The leveling agent was purchased from BYK Chemie, with the model number BYK-306;

[0046] The drier was purchased from Shanghai Tianyu Chemical Technology Co., Ltd., with the model number A-16;

[0047] The defoamer was purchased from Xipusen New Materials (Ningbo) Co., Ltd., with the model number DF800;

[0048] Waterborne polyurethane was purchased from Hefei Anke Fine Chemical Co., Ltd., with the model number PU144.

[0049] The present application will be further described in detail below with reference to Preparation Examples, Examples, and Comparative Examples.

[0050] Preparation Example 1.1

[0051] The preparation method of the binder includes the following steps:

[0052] I. Wash the waste PET material, cut it into 1 cm * 1 cm pieces, then alternately wash it three times in 1 mol / L HCl solution and 5 mol / L NaOH solution, then wash it three times in deionized water, and dry it in vacuum to obtain PET pieces. Then mix the PET pieces with NPG and DPG in a molar ratio of 1:1.5:1.5, preheat for 1 h at a temperature of 160 °C and a stirring speed of 250 rpm, then add tetrabutyl titanate, and the addition amount is 0.05 wt% of the total amount of PET pieces. Continue to stir for 3.5 h, then adjust the speed to 500 rpm and keep warm for 30 min. Turn off the stirring until the temperature of the reaction system drops to room temperature, and dry until the system reaches constant weight to finally obtain the PET oligomer capped with NPG and DPG;

[0053] II. Mix 200 g of the dried ethylene oxide-propylene oxide copolymer and 111 g of isophorone diisocyanate, stir at a speed of 250 rpm for 1 h, then add 4 mg of dibutyltin dilaurate, and react at 80 °C for 2 h to obtain a prepolymer. Lower the temperature to 50 °C, add 15 g of 2-hydroxyethyl disulfide and 25 g of the PET oligomer obtained in step I, and continue to stir for 3 h to obtain a binder. After testing, its light transmittance in the wavelength range of 400 - 800 nm is 95.2 - 95.8%.

[0054] Preparation Example 1.2

[0055] The preparation method of the binder includes the following steps:

[0056] I. Wash the waste PET material, cut it into 1 cm * 1 cm pieces, then alternately wash it three times in 1 mol / L HCl solution and 5 mol / L NaOH solution, then wash it three times in deionized water, and dry it in vacuum to obtain PET pieces. Then mix the PET pieces with NPG and DPG in a molar ratio of 1:1.5:1.5, preheat for 1 h at a temperature of 160 °C and a stirring speed of 250 rpm, then add tetrabutyl titanate, and the addition amount is 0.05 wt% of the total amount of PET pieces. Continue to stir for 3.5 h, then adjust the speed to 500 rpm and keep warm for 30 min. Turn off the stirring until the temperature of the reaction system drops to room temperature, and dry until the system reaches constant weight to finally obtain the PET oligomer capped with NPG and DPG;

[0057] II. Mix 200 g of the dried ethylene oxide - propylene oxide copolymer and 111 g of isophorone diisocyanate, stir at a speed of 250 rpm for 1 h, then add 4 mg of dibutyltin dilaurate, react at 80 °C for 2 h to obtain a prepolymer. Lower the temperature to 50 °C, add 30 g of 2 - hydroxyethyl disulfide and 6 g of the PET oligomer obtained in step I, and continue to stir for 3 h to obtain a binder. After testing, its light transmittance in the wavelength range of 400 - 800 nm is 95.5 - 95.9%.

[0058] Preparation Example 1.3

[0059] The preparation method of the binder is different from that of Preparation Example 1.1 in that: in step II, the amount of 2 - hydroxyethyl disulfide is 23.1 g, and the amount of the PET oligomer obtained in step I is 12.4 g. The rest are the same as those in Preparation Example 1.1, and a binder is obtained. After testing, its light transmittance in the wavelength range of 400 - 800 nm is 96.1 - 97.0%.

[0060] Preparation Example 2.1

[0061] The preparation method of the dispersant includes the following steps:

[0062] First, mix methacrylic acid, dimethylaminoethyl methacrylate, APEG - 300, and azobisisobutyronitrile in a molar ratio of 2:1:1:0.04, disperse them in an isopropanol solvent containing n - dodecyl mercaptan, where the content of n - dodecyl mercaptan is 1‰ of the total mass of methacrylic acid, dimethylaminoethyl methacrylate, APEG - 300, and azobisisobutyronitrile, and heat to reflux under nitrogen protection. Then start to drop - add the premixed solution, finish dropping within 180 min, keep warm at 65 °C for 1 h, then add azobisisobutyronitrile, and the added amount is the same as the first addition amount. After adding, continue to keep warm and react, and monitor the molecular weight of the product at any time during the reaction. When M w = 11500, cool the system to room temperature, add ammonia water to neutralize the system until it is neutral, quench the reaction, dilute with water, and then distill under reduced pressure until the system is of constant weight to obtain the dispersant.

[0063] Preparation Example 2.2

[0064] The preparation method of the dispersant includes the following steps:

[0065] First, mix methacrylic acid, dimethylaminoethyl methacrylate, APEG-300, and azobisisobutyronitrile in a molar ratio of 1:1:2:0.04, and disperse them in an isopropanol solvent containing dodecyl mercaptan. The content of dodecyl mercaptan is 1‰ of the total mass of methacrylic acid, dimethylaminoethyl methacrylate, APEG-300, and azobisisobutyronitrile. Then, heat the mixture to reflux under nitrogen protection, and start to dropwise add the premixed solution, which should be added dropwise within 180 min. After maintaining the temperature at 65°C for 1 h, add azobisisobutyronitrile again, and the added amount is the same as the first addition. After the addition, continue the heat preservation reaction, and monitor the molecular weight of the product at any time during the reaction. When M w = 12600, cool the system to room temperature and add ammonia water to neutralize the system until it is neutral. Quench the reaction, dilute with water, and then distill under reduced pressure until the system reaches a constant weight to obtain the dispersant.

[0066] Preparation Example 3.1

[0067] The preparation method of the dispersant is different from that of Preparation Example 2.1 in that APEG-300 is replaced by APEG-500, and the rest are the same as those in Preparation Example 2.1.

[0068] Preparation Example 3.2

[0069] The preparation method of the dispersant is different from that of Preparation Example 2.1 in that APEG-300 is replaced by APEG-700, and the rest are the same as those in Preparation Example 2.1.

[0070] Preparation Example 4.1

[0071] The preparation method of the dispersant is different from that of Preparation Example 3.1 in that the molar ratio of methacrylic acid, dimethylaminoethyl methacrylate, APEG-500, and azobisisobutyronitrile is 1:1:1:0.03, and the rest are the same as those in Preparation Example 3.1.

[0072] Preparation Example 4.2

[0073] The preparation method of the dispersant is different from that of Preparation Example 3.1 in that the molar ratio of methacrylic acid, dimethylaminoethyl methacrylate, APEG-500, and azobisisobutyronitrile is 2:1:2:0.05, and the rest are the same as those in Preparation Example 3.1.

[0074] Preparation Example 4.3

[0075] The preparation method of the dispersant is different from that of Preparation Example 3.1 in that the molar ratio of methacrylic acid, dimethylaminoethyl methacrylate, APEG-500, and azobisisobutyronitrile is 1.5:1:1.5:0.04, and the rest are the same as those in Preparation Example 3.1.

[0076] Preparation Example 5.1

[0077] The preparation method of the dispersant is different from Preparation Example 4.3 in that: after adding azobisisobutyronitrile, the reaction is continued, and the molecular weight of the product is monitored at any time during the reaction. When M w = 11800, the system is cooled to room temperature and neutralized with ammonia water until the system is neutral. The reaction is quenched, diluted with water, and then distilled under reduced pressure until the system reaches a constant weight to obtain the dispersant.

[0078] Preparation Example 5.2

[0079] The preparation method of the dispersant is different from Preparation Example 4.3 in that: after adding azobisisobutyronitrile, the reaction is continued, and the molecular weight of the product is monitored at any time during the reaction. When M w = 12000, the system is cooled to room temperature and neutralized with ammonia water until the system is neutral. The reaction is quenched, diluted with water, and then distilled under reduced pressure until the system reaches a constant weight to obtain the dispersant.

[0080] Preparation Example 5.3

[0081] The preparation method of the dispersant is different from Preparation Example 4.3 in that: after adding azobisisobutyronitrile, the reaction is continued, and the molecular weight of the product is monitored at any time during the reaction. When M w = 12200, the system is cooled to room temperature and neutralized with ammonia water until the system is neutral. The reaction is quenched, diluted with water, and then distilled under reduced pressure until the system reaches a constant weight to obtain the dispersant.

[0082] Preparation Example 5.4

[0083] The preparation method of the dispersant is different from Preparation Example 4.3 in that: after adding azobisisobutyronitrile, the reaction is continued, and the molecular weight of the product is monitored at any time during the reaction. When M w = 12400, the system is cooled to room temperature and neutralized with ammonia water until the system is neutral. The reaction is quenched, diluted with water, and then distilled under reduced pressure until the system reaches a constant weight to obtain the dispersant.

[0084] Comparative Preparation Example 1.1

[0085] The difference from Preparation Example 1.2 is that: in Step II, the amount of 2-hydroxyethyl disulfide used is 35 g, and the amount of the PET oligomer obtained in Step I used is 30 g. The rest are the same as Preparation Example 1.2. The light transmittance of the obtained binder in the wavelength range of 400 - 800 nm is 83.0 - 83.6%.

[0086] Comparative Preparation Example 1.2

[0087] The difference from Preparation Example 1.2 is that: in Step II, the amount of 2-hydroxyethyl disulfide used is 10 g, and the amount of the PET oligomer obtained in Step I used is 5 g. The rest are the same as Preparation Example 1.2. The light transmittance of the obtained binder in the wavelength range of 400 - 800 nm is 80.2 - 80.5%.

[0088] Comparative Preparation Example 2.1

[0089] It is different from Preparation Example 1.2 in that: in Step II, 2-hydroxyethyl disulfide is removed, and the amount of the PET oligomer obtained in Step I is 36 g, and the rest are the same as those in Preparation Example 1.2. The light transmittance of the obtained binder in the wavelength range of 400 - 800 nm is 81.9 - 82.4%.

[0090] Comparative Preparation Example 2.2

[0091] It is different from Preparation Example 1.2 in that: in Step II, the PET oligomer obtained in Step I is removed, and the amount of 2-hydroxyethyl disulfide is 36 g, and the rest are the same as those in Preparation Example 1.2. The light transmittance of the obtained binder in the wavelength range of 400 - 800 nm is 83.5 - 84.1%.

[0092] Comparative Preparation Example 3.1

[0093] It is different from Preparation Example 2.1 in that: after adding azobisisobutyronitrile, the reaction continues, and the molecular weight of the product is monitored at any time during the reaction. When M w = 10500, the system is cooled to room temperature and neutralized with ammonia water until the system is neutral, the reaction is quenched, diluted with water, and then distilled under reduced pressure until the system reaches a constant weight to obtain a dispersant.

[0094] Comparative Preparation Example 3.2

[0095] It is different from Preparation Example 2.1 in that: after adding azobisisobutyronitrile, the reaction continues, and the molecular weight of the product is monitored at any time during the reaction. When M w = 13200, the system is cooled to room temperature and neutralized with ammonia water until the system is neutral, the reaction is quenched, diluted with water, and then distilled under reduced pressure until the system reaches a constant weight to obtain a dispersant.

[0096] Comparative Preparation Example 4.1

[0097] It is different from Preparation Example 1.2 in that: the ethylene oxide - propylene oxide copolymer in Step II is replaced by polytetrahydrofuran, and the rest are the same as those in Preparation Example 1.2. The light transmittance of the obtained binder in the wavelength range of 400 - 800 nm is 89.7 - 90.3%.

[0098] Comparative Preparation Example 4.2

[0099] It is different from Preparation Example 1.2 in that: the ethylene oxide - propylene oxide copolymer in Step II is replaced by a tetrahydrofuran - ethylene oxide polymer, and the rest are the same as those in Preparation Example 1.2. The light transmittance of the obtained binder in the wavelength range of 400 - 800 nm is 87.9 - 88.5%.

[0100] Comparative Preparation Example 4.3

[0101] The difference from Preparation Example 1.2 is that the ethylene oxide-propylene oxide copolymer in Step II is replaced with a tetrahydrofuran-propylene oxide polymer, and the rest is the same as in Preparation Example 1.2. The light transmittance of the obtained binder in the wavelength range of 400 - 800 nm is 92.0 - 92.4%;

[0102] The tetrahydrofuran-propylene oxide polymer was prepared according to the description in the reference article "Synthesis Research of Tetrahydrofuran-Propylene Oxide Copolyether" by He Zhiqiang [D]. Jiangnan University, 2009. Specifically: Tetrahydrofuran, 1,2-propanediol, and boron trifluoride diethyl ether were blended and stirred, cooled to -5°C in an ice-salt bath, and then propylene oxide was added dropwise at a rate of 0.21 g / min. After the addition, the reaction continued at -5°C for 3 h to obtain a tetrahydrofuran-propylene oxide polymer with an average molecular weight of 2990. The amount of boron trifluoride diethyl ether used was 2.5 wt% of the total amount of tetrahydrofuran and propylene oxide, and the molar ratio of 1,2-propanediol, tetrahydrofuran, and propylene oxide was 0.057:2:1.

[0103] Example 1.1

[0104] A preparation process of an environmentally friendly black ink, comprising the following steps:

[0105] Mix the dispersant, carbon black, hydrophilic titanium dioxide, distilled water, and half of the auxiliaries prepared in Preparation Example 2.1, premix at a speed of 360 rpm for 10 min. After premixing evenly, add the binder prepared in Preparation Example 1.2, ball mill for 2 h, filter out the grinding balls, and then add the remaining half of the auxiliaries and mix evenly to finally obtain the environmentally friendly black ink. The dosage of each component is shown in Table 1.

[0106] Example 1.2

[0107] A preparation process of an environmentally friendly black ink, comprising the following steps:

[0108] Mix the dispersant, carbon black, hydrophilic titanium dioxide, distilled water, and half of the auxiliaries prepared in Preparation Example 2.2, premix at a speed of 360 rpm for 10 min. After premixing evenly, add the binder prepared in Preparation Example 1.1, ball mill for 2 h, filter out the grinding balls, and then add the remaining half of the auxiliaries and mix evenly to finally obtain the environmentally friendly black ink. The dosage of each component is shown in Table 1.

[0109] Example 1.3

[0110] A preparation process of an environmentally friendly black ink, comprising the following steps:

[0111] Mix the dispersant, carbon black, hydrophilic titanium dioxide, distilled water, and half of the additives prepared in Preparation Example 2.1, premix at a rotation speed of 360 rpm for 10 min. After premixing evenly, add the binder prepared in Preparation Example 1.2, ball mill for 2 h, filter out the grinding balls, then add the remaining half of the additives and mix evenly to finally obtain an environmentally friendly black ink. The dosage of each component is shown in Table 1.

[0112] Table 1 Dosage of each component in Examples 1.1 - 1.3 / kg

[0113]

[0114] Example 2

[0115] A preparation process of an environmentally friendly black ink, different from Example 1.1 in that: the binder prepared in Preparation Example 1.2 is replaced with the binder prepared in Preparation Example 1.3, and the rest are the same as in Example 1.1.

[0116] Examples 3.1 - 3.2

[0117] A preparation process of an environmentally friendly black ink, different from Example 1.1 in that: the dispersant prepared in Preparation Example 2.1 is respectively replaced with the dispersants prepared in Preparation Examples 3.1 - 3.2, and the rest are the same as in Example 1.1.

[0118] Examples 4.1 - 4.3

[0119] A preparation process of an environmentally friendly black ink, different from Example 3.1 in that: the dispersant prepared in Preparation Example 3.1 is respectively replaced with the dispersants prepared in Preparation Examples 4.1 - 4.3, and the rest are the same as in Example 3.1.

[0120] Examples 5.1 - 5.4

[0121] A preparation process of an environmentally friendly black ink, different from Example 4.3 in that: the dispersant prepared in Preparation Example 4.3 is respectively replaced with the dispersants prepared in Preparation Examples 5.1 - 5.4, and the rest are the same as in Example 4.3.

[0122] Comparative Example 1.1

[0123] Different from Example 1.1 in that: the binder prepared in Preparation Example 1.2 is replaced with waterborne polyurethane, and the rest are the same as in Example 1.1.

[0124] Comparative Examples 1.2 - 1.5

[0125] Different from Example 1.1 in that: the binder prepared in Preparation Example 1.2 is respectively replaced with the binders prepared in Comparative Preparation Examples 1.1 - 2.2, and the rest are the same as in Example 1.1.

[0126] Comparative Example 2.1

[0127] It is different from Example 1.1 in that the dispersant prepared in Preparation Example 2.1 is removed, the amount of carbon black used is 7.5 kg, and the rest are the same as in Example 1.1.

[0128] Comparative Examples 2.2 - 2.3

[0129] It is different from Example 1.1 in that the dispersant prepared in Preparation Example 2.1 is respectively replaced by the dispersants prepared in Comparative Preparation Examples 3.1 - 3.2, and the rest are the same as in Example 1.1.

[0130] Comparative Examples 3.1 - 3.3

[0131] It is different from Example 1.1 in that the binder prepared in Preparation Example 1.2 is respectively replaced by the binders prepared in Comparative Preparation Examples 4.1 - 4.3, and the rest are the same as in Example 1.1.

[0132] Performance Testing

[0133] Samples of the inks prepared from the examples and comparative examples were taken, sprayed and cured with PET as the substrate, and after drying for 24 h, printed specimens with an ink layer on the surface were made and the following tests were carried out:

[0134] 1. Referring to the records in GB / T 9754 - 2007, the glossiness of the ink layer was detected and the results were recorded in Table 2;

[0135] 2. Referring to the records in GB / T 13217.7 - 2023, the adhesion fastness grade of the ink layer (Grade I is the best) was detected and the results were recorded in Table 2;

[0136] 3. Using a friction fastness tester, the specimens were rubbed under a load of 200 g, and the peeling situation of the ink layer was observed. The maximum number of friction times without peeling of the ink layer was recorded in Table 2;

[0137] 4. Referring to the records in GB / T 1733 - 1993, the water resistance grade of the ink layer (Grade I is the best) was detected and the results were recorded in Table 2.

[0138] Table 2 Performance Testing Results

[0139]

[0140] Data Analysis:

[0141] As can be seen from Table 2, the glossiness of the ink layer formed after spraying and curing the ink prepared in Examples 1.1 - 1.3 of the present application can reach 82.6 - 83.2%, the maximum number of friction times under a load of 200 g can reach 138 - 147 times, the adhesion fastness can reach Grade II, and the water resistance grade can reach Grade II. This proves that the present application has achieved a sufficient improvement effect on the agglomeration phenomenon of carbon black from two aspects: reducing the carbon black dosage and enhancing the carbon black dispersion effect. Moreover, the high-transparency binder of the present application can ensure that the ink still has a high glossiness even when the carbon black dosage is reduced, with excellent appearance quality. The finally obtained environmentally friendly black ink combines environmental friendliness, durability, and high glossiness;

[0142] The glossiness and water resistance grade of the ink layer formed after spraying and curing the ink prepared in Example 2 are significantly better than those in Example 1.1, which proves that the present application further improves the light transmittance and water resistance of the binder by strictly controlling the weight ratio of 2-hydroxyethyl disulfide, PET oligomer, ethylene oxide-propylene oxide copolymer, and isophorone diisocyanate;

[0143] The maximum number of friction times and adhesion fastness of the ink layer formed after spraying and curing the ink prepared in Example 3.1 are significantly better than those in Example 1.1 and Example 3.2, which proves that the APEG-500 of the present application has a more suitable degree of polymerization than allyl polyoxyethylene ethers with other degrees of polymerization, and thus has a more suitable hydrophilic chain segment length. It can further balance the effect of the dispersant anchoring carbon black and its own dispersion effect, enabling the ink to have more excellent wear resistance after spraying and curing;

[0144] The performance indicators of the ink layer formed after spraying and curing the ink prepared in Example 4.3 are all relatively excellent, which proves that the present application controls the molar ratio of methacrylic acid, dimethylaminoethyl methacrylate, and allyl polyoxyethylene ether, controls the ratio of the hydrophilic segment to the hydrophobic segment of the dispersant. The appropriate hydrophilic segment can effectively improve the dispersion effect of carbon black and minimize its own aggregation degree in the aqueous system, while the appropriate hydrophobic segment can improve the water resistance of the ink and avoid the competitive association of itself in the aqueous system as much as possible, maintaining the water-oil balance of the ink, and optimizing the balance of the internal uniformity and waterproofness of the ink;

[0145] The performance indicators of the ink layer formed after spraying and curing the ink prepared in Example 5.3 are all better than those in Example 4.3, Examples 5.1 - 5.2, and Example 5.4, which proves that the present application monitors the molecular weight and controls the reaction time, and finally controls the average molecular weight of the finally obtained dispersant, thereby balancing the degree of dispersion assistance of the dispersant to carbon black and its own dispersion degree, making the dispersion effects of itself and carbon black reach the best level, and improving the adhesion fastness, wear resistance, and glossiness;

[0146] The glossiness of the ink layer formed after spraying and curing the ink prepared in Comparative Example 1.1 is only 70.8%, far lower than that of Example 1.1, which proves that by optimizing the light transmittance of the waterborne polyurethane with 2-hydroxyethyl disulfide and PET oligomer, the present application can maintain a good glossiness of the ink layer while reducing the carbon black dosage and ensuring the dispersibility of carbon black, thus guaranteeing the appearance quality;

[0147] The glossiness of the ink layers formed after spraying and curing the inks prepared in Comparative Examples 1.2 - 1.5 is inferior to that of Example 1.1, which proves that by modifying the waterborne polyurethane with 2-hydroxyethyl disulfide and PET oligomer simultaneously, the present application can effectively improve its light transmittance, and there is a good coordination effect between 2-hydroxyethyl disulfide and PET oligomer, which can jointly improve the light transmittance and water resistance of the binder;

[0148] The maximum number of friction times of the ink layer formed after spraying and curing the ink prepared in Comparative Example 2.1 is only 95 times, and the adhesion fastness is only Grade IV. Moreover, the carbon black dosage in Comparative Example 2.1 has been reduced by as much as 25wt% based on that of Example 1.1, but the uniformity in the system is still relatively low, which proves that the dispersant of the present application can indeed greatly improve the dispersibility of carbon black in the system and make the internal dispersion uniformity of the ink higher;

[0149] The maximum number of friction times and adhesion fastness of the ink layers formed after spraying and curing the inks prepared in Comparative Examples 2.2 - 2.3 are inferior to those of Example 1.1, which proves that by monitoring the molecular weight and controlling the reaction time, the present application finally controls the average molecular weight of the obtained dispersant, thereby balancing the degree of dispersion assistance of the dispersant to carbon black and its own dispersion degree, and improving the internal dispersion uniformity of the ink;

[0150] The glossiness of the ink layers formed after spraying and curing the inks prepared in Comparative Examples 3.1 - 3.3 is significantly lower than that of Example 1.1, which proves that the waterborne polyurethane prepared by the present application using ethylene oxide-propylene oxide copolymer and isophorone diisocyanate and combined with PET oligomer has the highest light transmittance, and thus the glossiness of the finally obtained ink is the best.

[0151] The examples of this specific embodiment are all preferred embodiments of the present application, and do not limit the protection scope of the present application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. An environmentally friendly black ink, characterized in that, The raw materials used include components with the following weight percentages: binder 50-55wt%; dispersant 1.5-2wt%; colorant 10-15wt%; filler 3-5wt%; solvent 20-25wt%; the balance being other additives; the dispersant is M w a block copolymer with M = 12200, the binder is a modified waterborne polyurethane, and it is prepared by the following method: I. Transesterify the PET material under the condition of adding a catalyst to form a PET oligomer capped with neopentyl glycol and dipropylene glycol; II. Mix 2-hydroxyethyl disulfide, PET oligomer, ethylene oxide-propylene oxide copolymer, and isophorone diisocyanate with a weight ratio of 2.31:1.24:20:11, add a catalyst, and react to obtain a binder; The dispersant is prepared by the following method: Methacrylic acid, dimethylaminoethyl methacrylate and allyl polyoxyethylene ether are mixed in a molar ratio of 1.5:1:1.5, and reacted under the protection of inert gas and in the presence of a catalyst. After cooling to room temperature, the pH is adjusted to neutral, and after distillation, dispersant M with w M = 12200 is obtained. The allyl polyoxyethylene ether is APEG-500.

2. The environmentally friendly black ink according to claim 1, characterized in that The raw materials used include the following components by weight percentage: binder 54wt%; dispersant 1.75wt%; colorant 12wt%; filler 4wt%; solvent 24wt%; the balance is other additives.

3. The preparation process of the environment-friendly black ink according to any one of claims 1-2, characterized in that, It includes the following steps: Premix the dispersant, colorant, filler, solvent, and half of the additives evenly, then add the binder and grind, and then add the remaining half of the additives and mix evenly to finally obtain an environmentally friendly black ink.

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