High adhesion water-based ink and its preparation process

Abstract

The application relates to a water-based ink with high adhesion and a preparation process thereof, wherein the water-based ink at least comprises the following raw materials in mass parts: 100-140 parts of acrylic emulsion; 120-160 parts of titanium white powder; 20-60 parts of ethylene glycol; 0-5 parts of functional additives; 80-100 parts of organic pigment; 400-600 parts of deionized water; porous cellulose, the added mass of the porous cellulose is 0.08-0.16 times the sum of the mass of the acrylic emulsion and the titanium white powder, and the Zeta potential of the porous cellulose at pH=7 is not more than -45 mV; the porous cellulose is obtained by dissolving cellulose diacetate, solidifying and phase separating, and then hydrolyzing and regenerating in a hydrolysis bath, the hydrolysis bath is an aqueous solution of sodium hydroxide and a potential adjusting agent, and the potential adjusting agent is at least one of triethylamine, diethylamine and ammonia water. The water-based ink in the application not only has good adhesion with a printing substrate, but also has good adhesion in itself.

Description

Technical Field

[0001] This application relates to the field of water-based inks, and more particularly to a high-adhesion water-based ink and its preparation process. Background Technology

[0002] With the continuous advancement of printing technology and the increasing awareness of environmental protection, traditional solvent-based inks, due to their high content of volatile organic compounds (VOCs), pose a potential threat to the environment and human health, and are gradually failing to meet the requirements of modern society for environmental protection and sustainable development. Therefore, developing environmentally friendly inks has become an important development direction for the printing industry.

[0003] Water-based inks, because they do not contain volatile organic solvents, significantly reduce VOC emissions, thereby mitigating air pollution, improving the environment for printing operators, and benefiting worker health. They can completely eliminate certain toxic and harmful substances found in solvent-based inks, eliminating harm to human health and contamination of packaged goods, thus improving overall environmental quality. They are particularly suitable for packaging and printing products with strict hygiene requirements, such as tobacco, alcohol, food, beverages, pharmaceuticals, and children's toys. Furthermore, they not only reduce the risk of fire caused by static electricity and flammable solvents, but also reduce the toxicity of residual substances on the printed surface and facilitate cleaning of printing equipment.

[0004] Water-based inks, as an environmentally friendly type of ink, are gradually gaining market attention due to their advantages such as low VOC emissions, good printability, and color reproduction. Water-based inks are mainly composed of water-soluble resins, pigments, water, and additives. During the printing process, water is used as a solvent or diluent, effectively reducing environmental pollution.

[0005] However, water-based inks still face some technical challenges in practical applications. Whether imported or domestically produced, their printing performance and quality do not meet the standards of solvent-based gravure inks. Currently, water-based inks suffer from drawbacks such as poor resistance to alkalis, ethanol, and water; slow drying; poor gloss; and a tendency to cause paper shrinkage. This is mainly due to the high surface tension of water (72 dyne / cm), making it difficult for the ink to wet and resulting in slow drying.

[0006] For example, water-based inks often exhibit poorer adhesion to substrates compared to solvent-based inks. Therefore, it is generally necessary to test the adhesion performance of water-based inks according to national standards. For instance, GB / T 13217.7-2023, "Ink Adhesion Test Method," specifies standards for determining the adhesion of various inks to substrates such as plastic films, aluminum foil, tinplate, and paper. Tape peeling is a commonly used method due to its simplicity. The principle involves measuring the degree to which the ink film on a specially treated substrate of different ink systems is adhered to or damaged by the tape, expressing the ink adhesion as a percentage (%). To obtain the ink adhesion data, a semi-transparent millimeter-sized grid paper is used to cover the peeled area. The number of grids occupied by the ink film and the number of grids occupied by the peeled ink layer are then counted.

[0007] The above test method can indeed effectively characterize the adhesion between ink and substrate. However, because the national standard test method does not focus on the ink adhering to the tape (only the surface ink), but only on the ink remaining on the substrate, the above test method cannot actually characterize the internal adhesion of the ink. In actual testing, it often happens that a thin layer of ink is adhering to the tape, but most of the ink remains on the substrate. Therefore, when calculating the adhesion data, this area is still considered as the part that was not peeled off.

[0008] Therefore, according to the national standard testing method, the measured ink adhesion data is relatively high, while the ink adhesion data calculated by referring to the ink stuck to the tape is often lower. This problem is unacceptable for packaging of high-end tobacco, high-end cosmetics, and high-end alcoholic beverages.

[0009] Therefore, there is a need for a water-based ink that not only has good adhesion to special printing substrates, but also has good adhesion to its own interior. Summary of the Invention

[0010] In order to ensure that water-based inks not only have good adhesion to the printing substrate, but also have good adhesion within the ink itself, this application provides a water-based ink with high adhesion and its preparation process.

[0011] In a first aspect, this application provides a high-adhesion water-based ink, employing the following technical solution: A high-adhesion water-based ink, comprising at least the following raw materials in parts by weight:

[0012] 100-140 parts acrylic emulsion;

[0013] 120-160 parts of titanium dioxide;

[0014] 20-60 parts of ethylene glycol;

[0015] Functional additives: 0-5 parts;

[0016] 80-100 parts organic pigments;

[0017] 400-600 parts deionized water;

[0018] The water-based ink also contains porous cellulose, the mass of which is 0.08-0.16 times the sum of the masses of the acrylic emulsion and the titanium dioxide. The zeta potential of the porous cellulose at pH=7 is not greater than -45mV. The porous cellulose is obtained by dissolving cellulose diacetate, solidifying and separating the phases, and then hydrolyzing and regenerating it in a hydrolysis bath. The hydrolysis bath is an aqueous solution of sodium hydroxide and a potential regulator, and the potential regulator is at least one of triethylamine, diethylamine, and ammonia.

[0019] By adopting the above technical solution, the abundant hydroxyl groups on the surface of the porous cellulose added in this application endow it with good hydrophilicity, which allows it to be uniformly dispersed. The uniformly dispersed regenerated cellulose can form a large number of hydrogen bonds with the water-based resin (acrylic emulsion) and titanium dioxide filler in the ink. Furthermore, its addition amount is not less than 0.08 times the sum of the mass of acrylic emulsion and titanium dioxide. Therefore, the addition of porous cellulose means that the large number of introduced hydrogen bonds can form a relatively complete hydrogen bond network, thereby improving the tightness of the connection between the components of the paint film.

[0020] In addition, adding slender fibers to water-based inks to improve the strength of the paint film is a common practice. However, the fibers added in this application are not slender cellulose fibers, but porous cellulose with a large number of micropores.

[0021] Compared to adding slender cellulose fibers, the irregularly shaped porous cellulose in this application enables the coating film to have better strength and significantly higher adhesion. On the one hand, compared to natural cellulose in nature, the phase separation regeneration process of regenerated cellulose introduces a large number of microporous structures, and these microporous structures generate obvious capillary phenomena. Therefore, the final coating film has a large amount of aqueous resin and other components embedded in the microporous structure of porous cellulose, forming a physical interlocking in addition to the hydrogen bond network. This greatly improves the compatibility and tightness of the various materials in the coating film, which greatly improves the peel strength of the coating film. It is worth noting that the so-called high peel strength is not only due to the coating film and the substrate, but more importantly, the tight bonding formed inside the coating film, making it difficult to peel off.

[0022] Of course, the amount of porous cellulose added should not exceed 0.16 times, so as not to introduce excessive hydroxyl groups that significantly increase the hydrophilicity of the paint film, resulting in excessive hydrophilic and hygroscopic properties, which in turn reduces the tightness of the bonding between materials in the paint film. In addition, the microporous structure of porous cellulose not only causes capillary adsorption of materials in the paint film, but also leads to capillary water absorption. Therefore, if the amount of porous cellulose added is too large, in addition to the excessive introduction of hydroxyl groups, the excessive capillary water absorption caused by the microporous structure will also lead to a decrease in the adhesion of the paint film due to increased water absorption.

[0023] Furthermore, the inventors of this application unexpectedly discovered that by adding negatively charged cellulose with a Zeta potential no greater than -45mV (absolute value no less than 45mV), the final paint film can exhibit higher strength and significantly better adhesion. This result is quite different from conventional understanding. It is generally believed that for cellulose materials, the higher the crystallinity of the cellulose, the higher the strength. When added to ink, it can give the paint film higher strength and adhesion between paint films, thereby preventing peeling (strong peel resistance). This is because the negative charge on porous cellulose is generally caused by the ionization of its hydroxyl groups. Since the crystalline regions of porous cellulose form highly ordered intermolecular and intramolecular hydrogen bonds, it is difficult for them to ionize. Only the free hydroxyl groups in the amorphous regions, which have not formed intermolecular and intramolecular hydrogen bonds, will ionize and exhibit electronegativity. This makes it possible for cellulose with higher crystallinity to have a smaller absolute value of Zeta potential. Therefore, to obtain a paint film with higher strength and better peel resistance, adding highly crystalline cellulose should be preferred, which naturally means that cellulose with a smaller absolute value of Zeta potential should be preferred.

[0024] However, the inventors of this application have discovered that by adding porous cellulose with a negative charge and a relatively large absolute value of Zeta potential, they were able to obtain a coating film with better peel resistance and strength, which is quite unexpected. As mentioned above, a large absolute value of Zeta potential usually means that the porous cellulose has lower crystallinity and lower strength. It is quite unexpected that the addition of porous cellulose with lower strength would result in higher peel resistance and coating film strength.

[0025] This is likely because, in the hydrolysis and regeneration process of the porous cellulose in this application, in addition to sodium hydroxide, at least one of triethylamine, diethylamine, and ammonia water is further added as a potential regulator, all of which are alkaline. The potential regulator not only further provides alkaline hydrolysis conditions, but more importantly, the addition of at least one of triethylamine, diethylamine, and ammonia water to the hydrolysis bath allows the hydrolyzed porous cellulose to carry a larger amount of negative charge, resulting in an increase in its absolute Zeta potential. During the hydrolysis and regeneration process, the hydrolysis of ester bonds on cellulose diacetate causes acetate ions to be removed and hydroxyl groups to be reintroduced. For hydrogen bonds in the crystalline region, since the potential regulator has difficulty entering, the hydroxyl groups in the crystalline region are less disturbed and will regenerate intermolecular and intramolecular hydrogen bonds to ensure high crystallinity. For hydroxyl groups in the amorphous region, the potential regulator forms hydrogen bonds with the reintroduced hydroxyl groups, thereby significantly reducing intermolecular and intramolecular hydrogen bonds in the amorphous region and increasing the amount of free hydroxyl groups. Furthermore, compared to the hydroxyl groups in the crystalline region, the hydroxyl groups in the amorphous region have significantly higher accessibility and are more easily ionized to exhibit electronegativity. Therefore, the addition of a potentiometer can achieve a larger absolute value of the Zeta potential by reducing the formation of intermolecular and intramolecular hydrogen bonds in the amorphous region, while having minimal impact on the crystalline region of porous cellulose. A larger absolute value of the Zeta potential means, on the one hand, that porous cellulose is more uniformly dispersed in water-based inks due to greater electrostatic repulsion, and on the other hand, that more free hydroxyl groups can form hydrogen bonds with water-based resins and titanium dioxide, thereby greatly improving the integrity of the hydrogen bond network. This significantly improves the strength of the final paint film and the bonding strength between the various materials in the film, thus greatly enhancing the peel resistance of the paint film.

[0026] In summary, porous cellulose with a large number of free hydroxyl groups can be obtained by adding a potential regulator in the hydrolysis bath. The addition of porous cellulose with good hydrophilicity, a large number of negative charges and a large number of micropores (Zeta potential not greater than -45mV), and controlling its addition amount to 0.08-0.16 times the sum of the mass of acrylic emulsion and titanium dioxide, can make the final paint film have significantly better adhesion between paint films.

[0027] Optionally, the porous cellulose has a zeta potential of not less than -85mV, and the added mass of the porous cellulose is 0.1-0.14 times the sum of the masses of the acrylic emulsion and the titanium dioxide.

[0028] By adopting the above technical solution, the charge carried by the porous cellulose should not be excessive (the absolute value should not be greater than 85mV). This is because when cellulose diacetate is hydrolyzed and regenerated in the hydrolysis bath, the free hydroxyl groups that the amorphous region can provide are limited. Therefore, if the absolute value of the zeta potential of the porous cellulose is greater than 85mV, it means that the crystalline region of the finally obtained porous cellulose is greatly affected and becomes an amorphous region. At this time, although there are indeed more free hydroxyl groups, the strength of the porous cellulose itself will decrease significantly, which will lead to a decrease in the strength and peel resistance of the finally obtained paint film.

[0029] Optionally, the concentration of sodium hydroxide in the hydrolysis bath is 0.2-1 g / L, and the concentration of the potentiometer is 0.05-0.1 g / L. The potentiometer is a mixture of triethylamine and ammonia in a mass ratio of 1:2-3.

[0030] By employing the above technical solution, the concentration of the potentiometer should not be too low or too high. If the concentration of the potentiometer is too high, it may undesirably interfere with the formation of intermolecular and intramolecular hydrogen bonds in the crystalline region during the hydrolysis and regeneration of cellulose acetate and the reintroduction of hydroxyl groups. This would result in an excessive decrease in the crystallinity of the final porous cellulose, making it difficult to provide good reinforcement and anti-peel properties in the coating film. Conversely, if the concentration of the potentiometer is too low, it may be difficult to prevent the formation of intermolecular and intramolecular hydrogen bonds in the amorphous regions of the porous cellulose, leading to a decrease in the number of free hydroxyl groups. Since the amount of porous cellulose added in this application is relatively small, the hydrogen bonds formed based on the porous cellulose are unlikely to form a complete network, naturally resulting in poor anti-peel properties.

[0031] Furthermore, the inventors of this application discovered that, compared to adding triethylamine, diethylamine, or ammonia alone, using a combination of triethylamine and ammonia as a potential regulator, at the same addition amount, resulted in a larger absolute Zeta potential value for the final porous cellulose. This is likely because ammonia has significantly higher permeability than triethylamine and diethylamine, making it easier to penetrate the amorphous regions of cellulose. Conversely, triethylamine is more basic than diethylamine and ammonia and has the ability to form hydrogen bonds, thus more readily combining with sodium hydroxide to attack the ester groups on the amorphous regions, promoting the removal of acetate ions and reintroducing hydroxyl groups. Therefore, the combination of triethylamine promoting hydrolysis and the highly permeable and hydrogen-bonding ammonia facilitates hydrolysis and regeneration of the amorphous regions, reducing the likelihood of intermolecular and intramolecular hydrogen bonding within the amorphous regions of cellulose, thereby obtaining the desired large absolute Zeta potential value for porous cellulose.

[0032] Optionally, the water-based ink may also contain 5-15 parts by weight of a thickener, wherein the thickener is a mixture of sodium alginate and sodium carboxymethyl cellulose in a mass ratio of 1-2:1.

[0033] By adopting the above technical solution, sodium alginate and sodium carboxymethyl cellulose are both common thickeners in water-based inks, and their combination can achieve good thickening and stabilizing effects. Sodium carboxymethyl cellulose is a water-soluble natural polymer compound with excellent thickening properties. Sodium alginate, on the other hand, is a polysaccharide extracted from brown algae, possessing excellent gelling ability and stability. Combining these two functional substances further enhances the overall performance of sodium carboxymethyl cellulose plus sodium alginate. Stability is also a key performance characteristic of many products. Sodium carboxymethyl cellulose plus sodium alginate effectively prevents the sedimentation and aggregation of solid particles or bubbles in liquid and gel systems. Its excellent stability ensures long-term stability of the product during storage, transportation, and use, preventing stratification and sedimentation. This is particularly important for water-based ink systems containing titanium dioxide inorganic particles.

[0034] Optionally, the thickener can be added by first blending it with the porous cellulose and then adding it to the water-based ink.

[0035] By adopting the above technical solution, the inventors of this application discovered that if thickeners are directly added to water-based inks, the water-based inks are prone to separation. This may be because the thickeners combine with titanium dioxide, which has a high surface energy and tends to agglomerate to reduce its surface energy. Once the titanium dioxide and thickeners agglomerate, undesirable sedimentation and separation problems will occur.

[0036] In particular, the uniform addition of thickeners has always been a difficult technical problem to solve. Thickeners are often added in excess in certain areas, resulting in excessively high local viscosity. This makes it easier for them to react with fillers such as titanium dioxide to form uncontrollable agglomerated particles. During long-term storage, these agglomerated particles can cause stratification. After the paint film is formed, these agglomerated particles become defects. Once there are defects in the paint film, its local anti-peel performance will decrease.

[0037] To address this issue, this application controls the addition of the thickener by first blending it with porous cellulose to allow it to adsorb into the microporous structure of the cellulose. Therefore, when added to the water-based ink, the thickener located within the porous cellulose is slowly released, significantly improving the uniformity of thickener addition. Furthermore, as mentioned earlier, the porous cellulose added in this application carries a large amount of charge, which not only ensures its own excellent dispersion uniformity but also greatly improves the dispersion uniformity of fillers such as titanium dioxide within the system. Thus, the already uniformly dispersed porous cellulose ensures that the slowly released thickener within the microporous structure is also evenly distributed. Combined with the uniform dispersion of titanium dioxide filler due to the electrostatic repulsion of the porous cellulose, the possibility of localized agglomeration is significantly reduced. This greatly reduces the stratification problem caused by agglomerate particles and significantly alleviates the problem of decreased paint film peel resistance caused by uneven thickener addition.

[0038] Optionally, the porous cellulose also contains embedded inorganic particles, including zirconium oxide and zinc oxide, and the mass ratio of the inorganic particles to the regenerated cellulose is 1:10-20.

[0039] By employing the above technical solution, it is noteworthy that when sodium alginate is present in the thickener, the presence or absence of inorganic particles composed of zirconium oxide and zinc oxide embedded within the porous cellulose unexpectedly has a significant impact on the anti-delamination and anti-peel properties of water-based inks. Specifically, the inventors of this application found in control experiments that if no inorganic particles were added to the porous cellulose, the anti-delamination and anti-peel properties of the water-based inks showed a significant decrease. This was quite unexpected, as inorganic particles embedded within porous cellulose are generally considered not to affect the anti-delamination and anti-peel properties of water-based inks.

[0040] This may be because, although sodium alginate can be used to adjust the viscosity of the system, its molecular chain is unstable and easily degrades during production at slightly higher temperatures or during high-temperature storage. This leads to unpredictable changes in the viscosity of water-based inks, resulting in a decrease in their anti-separation properties. Similar to sodium alginate, the production process of water-based inks inevitably involves a certain degree of heating, and since acrylic emulsions are alkali-soluble resins, the entire system is alkaline and at relatively high temperatures. Under these conditions, regenerated cellulose is prone to uncontrolled degradation.

[0041] Zinc oxide is a commonly used whitening agent, exhibiting excellent whitening effects in water-based inks. Furthermore, zinc oxide can act as a catalyst, promoting the curing reaction of water-based inks. This is highly beneficial for improving the printing speed and quality of water-based inks. Zirconia embedded within porous cellulose has excellent thermal insulation properties, not only preventing the high-temperature alkaline hydrolysis of regenerated cellulose but also significantly reducing the degradation process of sodium alginate, thereby mitigating the adverse effects caused by the hydrolysis or degradation of both. Therefore, zinc oxide's curing-promoting effect can, on the one hand, prevent insufficient ink curing and drying speed leading to problems with film adhesion and water resistance; on the other hand, it can appropriately reduce the high-temperature drying and curing time of water-based inks. Meanwhile, the excellent thermal insulation effect of zirconium oxide can induce high-temperature alkaline hydrolysis of porous cellulose. The synergistic effect of both allows the porous cellulose to maintain good properties, resulting in a film with better peel resistance.

[0042] In addition, as mentioned above, regenerated cellulose exhibits significantly stronger capillary water absorption compared to natural cellulose due to its microporous structure. Inorganic particles filling this microporous structure can alleviate this phenomenon to some extent. Furthermore, regenerated cellulose is softer, and the embedded inorganic particles significantly improve its strength, allowing the cellulose dispersed within the coating film to provide good anchoring. Overall, the embedded inorganic particles reduce capillary water absorption and primarily demonstrate the positive impact of hydrogen bonding formed by cellulose itself on water resistance, which also improves the peel resistance of the coating film.

[0043] Optionally, the inorganic particles are a mixture of zirconium oxide and zinc oxide in a mass ratio of 3-5:1.

[0044] By adopting the above technical solution, the high absolute value of the zeta potential of porous cellulose means that zinc oxide and zirconium oxide are uniformly dispersed along with the uniform dispersion of porous cellulose. This greatly avoids the problem of excessively high local viscosity and uneven curing caused by the local enrichment of inorganic particles, which leads to defects in the paint film.

[0045] Based on this, the amount of zirconium oxide added is controlled to be 3-5 times that of zinc oxide. This is because zinc oxide has a slightly greater impact on the viscosity of water-based inks. In order to avoid an undesirable increase in the viscosity of water-based inks, and also to avoid excessive zinc oxide in some areas causing the water-based inks that penetrate into and surround the porous cellulose to cure too quickly, which would lead to undesirable paint film problems, zinc oxide is preferably added in small amounts.

[0046] Optionally, the porous cellulose is prepared by the following process:

[0047] A1. Inorganic particle dispersion: Inorganic particles are placed in a solvent and ultrasonically dispersed to obtain a dispersion, wherein the solvent is at least one of acetone, dioxane, dimethylacetamide, and N-methylpyrrolidone.

[0048] A2. Dissolving: Add cellulose diacetate to the dispersion and dissolve to obtain a blend. The concentration of cellulose diacetate is 8-12 wt%, and the mass ratio of the inorganic particles to the regenerated cellulose is 1:10-20.

[0049] A3. Phase separation curing: The blended liquid is placed in a phase separation bath to separate cellulose diacetate into a multi-microporous structure and allow inorganic particles to adhere to the fiber. The mixture is then filtered to obtain a semi-finished product. The phase separation bath is an aqueous solution of a small molecule alcohol. The surface tension of the phase separation bath is not greater than 40 mN / m. The small molecule alcohol is at least one of ethanol, propanol, and isopropanol.

[0050] A4. Hydrolysis and regeneration: The semi-finished product is mixed with a hydrolysis bath to hydrolyze cellulose diacetate to remove acetate and regenerate it into cellulose. The hydrolysis bath is an aqueous solution of sodium hydroxide and a potential regulator. The potential regulator is at least one of triethylamine, diethylamine, and ammonia. After hydrolysis, the product is filtered out and washed to obtain porous cellulose.

[0051] By adopting the above technical solution, in step A3, the low surface tension phase-separation bath can improve its permeability, thereby exchanging with the solvent in the blend more quickly to form micropores with smaller pore sizes. The low concentration of cellulose diacetate results in a large number of micropores, even though the pore size is small. Therefore, the low surface tension phase-separation bath enables the final regenerated cellulose to have a large number of small-sized microporous structures. This allows for better physical integration after adding water-based inks, and facilitates the formation of hydrogen bond networks through more uniformly dispersed and exposed hydroxyl groups, improving water resistance and anti-delamination properties.

[0052] The role of the potentiometer in step A4 is as described above and will not be repeated here.

[0053] Optionally, step A4 specifically includes the following steps:

[0054] A41. Cold mixing: The semi-finished product is mixed with a hydrolysis bath, and the system temperature is controlled to be no more than 20°C to obtain a cold mixing system.

[0055] A42. Heating hydrolysis: Heating the cold mixed system to 60-80℃ allows cellulose diacetate to hydrolyze and regenerate into regenerated cellulose under alkaline conditions.

[0056] A43. Filtration and washing: The regenerated cellulose and inorganic particles embedded in the micropores of the regenerated cellulose in the hydrolysis system are filtered and washed until neutral to obtain porous cellulose.

[0057] By adopting the above technical solution, compared with directly mixing the semi-finished product with sodium hydroxide solution under high temperature conditions for hydrolysis and regeneration, the method of cold mixing followed by heating and hydrolysis can ensure that sodium hydroxide first uniformly adheres to the fiber before hydrolysis, thereby improving the hydrolysis uniformity of cellulose diacetate and correspondingly improving the defect resistance of water-based inks.

[0058] Secondly, this application provides a preparation process for water-based ink, employing the following technical solution:

[0059] A process for preparing a water-based ink includes the following steps:

[0060] S1. Thickening blending: Prepare an aqueous solution of thickener at a concentration of 3-5 wt%, then blend it evenly with porous cellulose. Dry the blend to allow the thickener to adhere to the porous cellulose.

[0061] S2. Stirring and initial mixing: Mix all raw materials except acrylic emulsion and porous cellulose evenly, then add acrylic emulsion and stir evenly to obtain the initial mixture.

[0062] S3. Sand milling: Transfer the initial mixture to a sand mill for a first-stage sand milling, then add porous cellulose for a second-stage sand milling. After sand milling, filter the material. During the first-stage grinding, indirectly cool with cooling water to control the grinding temperature at 25-35℃. Grind until the fineness is no greater than 15μm to complete the first-stage grinding. Then, cut off the cooling water and add porous cellulose with thickener attached. Keep grinding until the temperature inside the mill reaches 50-60℃ to complete the second-stage grinding.

[0063] S4. Packaging and storage.

[0064] By adopting the above technical solution, the special two-stage grinding method ensures good grinding effect by first grinding with high viscosity at low temperature. Then, by adding porous cellulose and grinding with low viscosity at high temperature, it can avoid problems such as difficulty in discharging and clogging of the sand mill caused by high viscosity. On the other hand, it can prevent the soft regenerated cellulose from being excessively ground and broken, making it difficult to play the role of local pinning and physical embedding. Attached Figure Description

[0065] Figure 1 This is a typical SEM image of porous cellulose obtained in this application. Detailed Implementation

[0066] The following provides a further detailed description of this application.

[0067] The following are examples of the preparation of porous cellulose disclosed in this application:

[0068] Preparation Example 1

[0069] The porous cellulose in this preparation example was prepared through the following process steps:

[0070] A1. Inorganic Particle Dispersion: Inorganic particles were placed in a solvent and ultrasonically dispersed to obtain a dispersion. N-methylpyrrolidone was used as the solvent. The total concentration of inorganic particles was controlled at 0.67 wt%. In this preparation example, the inorganic particles were a mixture of zirconium oxide and zinc oxide at a mass ratio of 4:1. The ultrasonic dispersion process only needed to ensure sufficient dispersion of the inorganic particles and could be adjusted routinely. In this preparation example, the ultrasonic power was 50 W, and the ultrasonic time was 15 min. The zirconium oxide was purchased from DKK Corporation (Daiichi Rare Element Chemical Industry Co., Ltd.), specifically model UEP-50. 50 Its thickness is 0.07-0.27 μm, and its specific surface area is 40-60 m². 2 / g; the zinc oxide is DXN-ZY06 from Chaotai Metal Materials, with a primary particle size of approximately 200-300 nm and a specific surface area greater than 5 m². 2 / g.

[0071] A2. Dissolution: Add cellulose diacetate to the dispersion and dissolve to obtain a blend. The concentration of cellulose diacetate added is 10 wt%. In the blend, the mass ratio of inorganic particles to cellulose diacetate is 1:15. The cellulose diacetate was purchased from Daicel Co., Ltd., specifically CAFBLO® Flake L-50, with an esterification rate (acetic acid binding rate, degree of acetylation) of 54%-56%.

[0072] A3. Phase Separation and Curing: The blend is injected into a stirred phase separation bath via a nozzle, causing cellulose diacetate to separate into a multi-microporous structure and for zirconium oxide to adhere to the fibers. The resulting product is filtered to obtain a semi-finished product. The phase separation bath is an aqueous solution of a small molecule alcohol. In this preparation example, the phase separation bath is an aqueous solution of ethanol, and the surface tension of the phase separation bath is controlled to be approximately 35 mN / m. The spraying speed of the blend is 6 L / min, and the stirring speed of the phase separation bath is 75 r / min.

[0073] A4. Hydrolysis and Regeneration: The semi-finished product is mixed with a hydrolysis bath to hydrolyze cellulose diacetate to remove acetate ions and regenerate it into cellulose. The cellulose is then filtered and washed to obtain regenerated cellulose containing embedded inorganic particles. Specifically, this step employs a process of cold mixing followed by hot hydrolysis, with the specific steps as follows:

[0074] A41. Cold mixing: The semi-finished product is mixed with the hydrolysis bath, and the system temperature is controlled to be no higher than 20°C. Specifically, in this preparation example, the system temperature is controlled to be 15°C to obtain a cold-mixed system. The hydrolysis bath is an aqueous solution of sodium hydroxide and a potentiometer. The concentration of the sodium hydroxide solution is controlled to be 0.5 g / L, and the total concentration of the potentiometer is controlled to be 0.075 wt%. Specifically, the potentiometer is a mixture of triethylamine and ammonia water at a mass ratio of 1:2.5, and the concentration of ammonia water used in this preparation example is 25%. In step A2 of this preparation example, a total of 50 g of cellulose diacetate is used. Therefore, the total amount of sodium hydroxide added in this step is controlled to be 20 g. Since the concentration of the sodium hydroxide solution is controlled to be 0.5 g / L, a total of 40 L of sodium hydroxide solution is required to ensure that the mass ratio of sodium hydroxide in the sodium hydroxide solution to the mass of cellulose diacetate added in step A2 is 1:2.5.

[0075] A42. Heating hydrolysis: Heating the cold mixed system to 70°C causes cellulose diacetate to hydrolyze and regenerate into regenerated cellulose under alkaline conditions.

[0076] A43. Filtration and washing: The regenerated cellulose and zirconium oxide embedded in the micropores of the regenerated cellulose in the hydrolysis system are filtered and washed until neutral to obtain porous cellulose; the scanning electron microscope image of the obtained porous cellulose is shown below. Figure 1 As shown. The porous fiber prepared according to this preparation example had a zeta potential of -66 mV at pH=7.

[0077] Preparation Examples 2-7

[0078] The main difference between Preparation Examples 2-7 and Preparation Example 1 lies in the appropriate adjustments made to each preparation process step, as detailed in the table below:

[0079]

[0080] Specifically, the main difference between Preparation Example 2 and Preparation Example 1 lies in the adjustment of components and process parameters, and the mass ratio of zirconium oxide to zinc oxide in the inorganic particles is controlled at 3:1, while the mass ratio of triethylamine to ammonia in the potentiometer is controlled at 1:2. The main difference between Preparation Example 3 and Preparation Example 1 lies in the adjustment of components and process parameters, and the mass ratio of zirconium oxide to zinc oxide in the inorganic particles is controlled at 5:1, while the mass ratio of triethylamine to ammonia in the potentiometer is controlled at 1:3.

[0081] The main difference between Preparation Example 4 and Preparation Example 1 is that the inorganic particles used are only zirconium oxide and no zinc oxide is added. The main difference between Preparation Example 5 and Preparation Example 1 is that the inorganic particles used are only zinc oxide and no zirconium oxide is added.

[0082] No inorganic particles were added in preparation example 6.

[0083] The main difference between Preparation Example 7 and Preparation Example 1 is that, while keeping the total mass of inorganic particles unchanged, the mass ratio of zirconium oxide to zinc oxide in the inorganic particles is controlled to be 1:1.

[0084] The main difference between Preparation Examples 8-12 and Preparation Example 1 is that, while keeping the amount of potential regulator added constant, the type and compounding method of the potential regulator were adjusted to confirm the effect of different compounding methods on the Zeta potential of the prepared porous cellulose.

[0085] The main difference between Preparation Example 13 and Preparation Example 1 is that a slightly excessive amount of potentiometer was added.

[0086] The main difference between Preparation Example 14 and Preparation Example 1 is that no potential regulator was added during the hydrolysis and regeneration process.

[0087] The following are examples of the water-based inks disclosed in this application:

[0088] Example 1: This application discloses a high-adhesion water-based ink, which specifically comprises the following raw materials in parts by weight:

[0089] 120 parts acrylic emulsion;

[0090] 140 parts of titanium dioxide;

[0091] Thickener 10 parts;

[0092] 3 parts of functional additives;

[0093] 90 parts organic pigments;

[0094] 40 parts ethylene glycol;

[0095] 500 parts deionized water;

[0096] 31.2 parts of porous cellulose, which is 0.12 times the sum of the mass of acrylic emulsion and titanium dioxide added.

[0097] Specifically, the acrylic emulsion in this embodiment was purchased from Dow Chemical's RESIN HF-05A waterborne self-crosslinking thermosetting acrylic resin, with a solid content of approximately 40%; the titanium dioxide was specifically Bluestar Dahua's anatase titanium dioxide DHA-100; the thickener was a mixture of sodium alginate and sodium carboxymethyl cellulose at a mass ratio of 1.5:1; the functional additives were specifically 1 part defoamer and 2 parts leveling agent, the defoamer being Dow Chemical's DC65 silicone defoamer and the leveling agent being BYK-333 silicone leveling agent; the organic pigment could be conventionally selected, and in this embodiment, phthalocyanine blue BGS was selected as the organic pigment.

[0098] The high-adhesion water-based ink in this embodiment is prepared through the following process steps:

[0099] S1. Thickening and blending: Prepare an aqueous solution of thickener at a concentration of 4 wt%, then blend it evenly with porous cellulose. Dry the blend to allow the thickener to adhere to the porous cellulose. It should be noted that the concentration of the thickener only needs to ensure that it can be well dispersed without obvious clumping. Of course, in order to avoid excessive energy waste during the drying process, the concentration of the thickener should not be too high. Overall, preparing the thickener solution within a reasonable range has no substantial impact on the final performance.

[0100] S2. Initial mixing: Mix all raw materials except acrylic emulsion and porous cellulose evenly, then add acrylic emulsion and mix evenly to obtain the initial mixture.

[0101] S3. Sand milling: Transfer the initial mixture to a sand mill for a first-stage sand milling, then add porous cellulose for a second-stage sand milling. After sand milling, filter the material. During the first-stage grinding, indirectly cool with cooling water to control the grinding temperature at 30°C. Grind until the fineness is no greater than 15μm to complete the first-stage grinding. Then, cut off the cooling water and add porous cellulose with thickener attached. Keep grinding until the temperature inside the mill reaches 55°C to complete the second-stage grinding.

[0102] S4. Packaging and storage.

[0103] Examples 2-16 differ from Example 1 mainly in that the raw material sources, proportions, and process parameters are fine-tuned, as detailed in the table below.

[0104] Specifically, the main difference between Examples 2 and 3 and Example 1 is that the ink formulation and process are adjusted.

[0105] The main difference between Example 4 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 was replaced with the same mass of porous cellulose prepared in Preparation Example 13.

[0106] The main difference between Example 5 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 8 of the same mass.

[0107] The main difference between Example 6 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 was replaced with the porous cellulose prepared in Preparation Example 9 of the same mass.

[0108] The main difference between Example 7 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 10 of the same mass.

[0109] The main difference between Example 8 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 11 of the same mass.

[0110] The main difference between Example 9 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 12 of the same mass.

[0111] The main difference between Example 10 and Example 1 is that the thickener was not added after being blended with porous cellulose. In other words, step S1 was not performed in Example 10, but the thickener was added directly to the blend in step S2.

[0112] The main difference between Example 11 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 7 of the same mass.

[0113] The main difference between Example 12 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 6 of the same mass.

[0114] The main difference between Example 13 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 5 of the same mass.

[0115] The main difference between Example 14 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 4 of the same mass.

[0116] The main difference between Example 15 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 3 of the same mass.

[0117] The main difference between Example 16 and Example 1 is that the porous cellulose prepared in Preparation Example 1 of the original Example 1 is replaced with the porous cellulose prepared in Preparation Example 2 of the same mass.

[0118] Comparative Example

[0119] Comparative Example 1

[0120] The only difference between Comparative Example 1 and Example 1 is that the porous cellulose used in Comparative Example 1 is not the porous cellulose obtained in the preparation examples of this application, but a commercially available microcrystalline cellulose, specifically Toncellus® TC105 from Dongchen Pharmaceutical, whose D 50 Its thickness is 20 μm, and its bulk density is approximately 0.25 g / cm³. 3 .

[0121] Comparative Example 2

[0122] The only difference between Comparative Example 2 and Example 1 is that a smaller amount of porous cellulose was added in Comparative Example 2. Specifically, the amount of porous cellulose added was 5.2 parts, which is 0.02 times the sum of the mass of acrylic emulsion and titanium dioxide added.

[0123] Comparative Example 3

[0124] The only difference between Comparative Example 3 and Example 1 is that Comparative Example 3 added an excess of porous cellulose, which was 65 parts, 0.25 times the sum of the mass of acrylic emulsion and titanium dioxide.

[0125] Comparative Example 4

[0126] The only difference between Comparative Example 4 and Example 1 is that the porous cellulose added in Comparative Example 4 is the porous cellulose obtained in Preparation Example 14 without the addition of a potential regulator.

[0127]

[0128]

[0129] Performance testing and data

[0130] Adhesion testing methods

[0131] The water resistance of the water-based inks prepared in the embodiments and comparative examples of this application was tested according to the provisions of standard GB / T 13217.7-2023, "Ink Adhesion Test Method". It is particularly important to note that in this test method, instead of covering the substrate with semi-transparent millimeter-scale paper, semi-transparent millimeter-scale paper is used to cover the adhesive tape. The number of squares occupied by the removed ink layer and the total number of squares are counted, expressed as a percentage. The higher the value, the worse the adhesion and the worse the peel resistance. This test method not only requires that the paint film not be completely peeled off, but also includes the peeling of the surface layer, thus better demonstrating the peel resistance of the paint film.

[0132] Peel resistance / % Example 1 0 Example 2 2.4 Example 3 1.1 Example 4 5.2 Example 5 3.4 Example 6 3.8 Example 7 2.9 Example 8 2.2 Example 9 3.3 Example 10 5.6 Example 11 4.9 Example 12 6.4 Example 13 5.9 Example 14 3.9 Example 15 1.4 Example 16 2.1 Comparative Example 1 10.6 Comparative Example 2 9.4 Comparative Example 3 9.7 Comparative Example 4 8.8

[0133] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A high adhesion water-based ink, characterized by: Raw materials including at least the following quality parts: Acrylic emulsion 100-140 parts; Titanium white 120-160 parts; Ethylene glycol 20-60 parts; Functional additives 0-5 parts; Organic pigments 80-100 parts; Deionized water 400-600 parts; The water-based ink further comprises porous cellulose, the added mass of the porous cellulose is 0.08-0.16 times the sum of the mass of the acrylic emulsion and the titanium white, the Zeta potential of the porous cellulose at pH=7 is not more than-45mV; the porous cellulose is obtained by dissolving cellulose diacetate, phase separation and solidification, and then hydrolysis and regeneration in a hydrolysis bath, the hydrolysis bath is an aqueous solution of sodium hydroxide and a potential adjusting agent, the potential adjusting agent is at least one of triethylamine, diethylamine, and ammonia water; the porous cellulose is prepared from regenerated cellulose, and inorganic particles are embedded in the porous cellulose, the inorganic particles include zirconium oxide and zinc oxide, and the mass ratio of the inorganic particles to the regenerated cellulose is 1:10-20.

2. The high adhesion water-based ink according to claim 1, characterized in that: The Zeta potential of the porous cellulose is not less than-85mV, and the added mass of the porous cellulose is 0.1-0.14 times the sum of the mass of the acrylic emulsion and the titanium white.

3. The high adhesion water-based ink according to claim 1, characterized in that: The concentration of sodium hydroxide in the hydrolysis bath is 0.2-1g / L, and the concentration of the potential adjusting agent is 0.05-0.1g / L, and the potential adjusting agent is a mixture of triethylamine and ammonia water in a mass ratio of 1:2-3.

4. The high adhesion water-based ink according to claim 1, characterized in that: The water-based ink further comprises 5-15 parts of a thickening agent, and the thickening agent is a mixture of sodium alginate and sodium carboxymethyl cellulose in a mass ratio of 1-2:

1.

5. The high adhesion water-based ink according to claim 4, characterized in that: The thickening agent is added by blending with the porous cellulose first and then added to the water-based ink.

6. The high adhesion water-based ink according to claim 1, characterized in that: The inorganic particles are a mixture of zirconium oxide and zinc oxide in a mass ratio of 3-5:

1.

7. The high adhesion water-based ink according to any one of claims 1 to 6, characterized in that: The porous cellulose is prepared by the following process: A1, inorganic particle dispersion, the inorganic particles are placed in a solvent and ultrasonically dispersed to obtain a dispersion liquid, the solvent is at least one of acetone, dioxane, dimethylacetamide, and N-methyl pyrrolidone; A2, dissolving, cellulose diacetate is added to the dispersion liquid and dissolved to obtain a blended liquid, the added concentration of cellulose diacetate is 8-12wt%, and the mass ratio of the inorganic particles to the regenerated cellulose is 1:10-20; A3, phase separation and solidification, the blended liquid is placed in a phase separation bath to make the cellulose diacetate phase separate into a microporous structure and make the inorganic particles adhere to the fibers, and then a semi-finished product is obtained by filtration, the phase separation bath is an aqueous solution of a small molecule alcohol, the surface tension of the phase separation bath is not more than 40mN / m, and the small molecule alcohol is at least one of ethanol, propanol, and isopropanol; A4, hydrolysis and regeneration, the semi-finished product is blended with a hydrolysis bath to hydrolyze and regenerate cellulose from diacetate, the hydrolysis bath is an aqueous solution of sodium hydroxide and a potential adjusting agent, the potential adjusting agent is at least one of triethylamine, diethylamine, and ammonia water, and the porous cellulose is obtained by filtration and washing after hydrolysis is completed.

8. The high adhesion water-based ink according to claim 7, characterized in that: The step A4 specifically comprises the following steps: A41, cold mixing, blending the semi-finished product with the hydrolysis bath, and controlling the system temperature to be not more than 20℃, to obtain a cold mixing system; A42, heating hydrolysis, heating the cold mixing system to 60-80℃ to hydrolyze the diacetic acid cellulose under alkaline conditions to regenerate regenerated cellulose; A43, filtering and washing, filtering and washing the regenerated cellulose in the hydrolysis system and the inorganic particles embedded in the micropores of the regenerated cellulose to neutral, to obtain porous cellulose.

9. Process for the production of the aqueous ink according to any one of claims 1 to 8, characterized in that: The process comprises the following steps: S1, thickening blending, configuring the thickening agent into an aqueous solution with a concentration of 3-5wt%, then blending uniformly with the porous cellulose, and drying the blend to make the thickening agent adhere to the porous cellulose; S2, stirring initial mixing, blending and stirring all raw materials except the acrylic emulsion and the porous cellulose uniformly, then adding the acrylic emulsion and stirring uniformly to obtain an initial mixture; S3, sanding, transferring the initial mixture to a sanding machine for one-stage sanding, then adding the porous cellulose for two-stage sanding, and filtering the material after sanding; During the first-stage grinding, indirect cooling by cooling water is used to control the grinding temperature to 25-35℃, and the grinding is completed when the fineness is not more than 15μm; Then the cooling water is cut off and the porous cellulose with the thickening agent adhered is added, and the grinding state is maintained until the temperature in the grinding machine reaches 50-60℃, and the two-stage grinding is completed; S4, packaging, storage and transportation.

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