A waterborne polyurethane dispersion, its preparation method, and its application in ink.

Abstract

This invention provides an aqueous polyurethane dispersion, its preparation method, and its application in water-based inks. The aqueous polyurethane dispersion, by weight, comprises 50-70 parts of polycarbonate diol, 10-30 parts of polyester diol, 15-25 parts of diisocyanate, 2-8 parts of epoxy resin, 1-5 parts of aminated cage-type silsesquioxane, 3-6 parts of dimethylolpropionic acid, 1-4 parts of hydroxyl silicone oil, 2-5 parts of amino acid ring-opening epoxy resin adduct, 0.5-2 parts of crosslinking agent, 2-4 parts of chain extender, 2-5 parts of neutralizing agent, and an appropriate amount of water. Through the synergistic effect of the components, this application achieves a color development ΔE=1.2, a wettability contact angle of 38°, adhesion grade 0, gloss of 92%, and excellent water resistance, meeting the requirements of high-end water-based inks.

Description

Technical Field

[0001] This invention relates to the field of polymer pigment technology, specifically to an aqueous polyurethane dispersion, its preparation method, and its application in water-based inks. Background Technology

[0002] With increasing environmental awareness and increasingly stringent regulations on volatile organic compound (VOC) emissions, water-based inks are gradually replacing traditional solvent-based inks due to their advantages: using water as a dispersion medium, emitting no toxic or harmful solvents, being non-flammable and non-explosive, and having minimal impact on operator health. Among these, water-based polyurethane dispersions, with their unique microphase separation structure, offer excellent film-forming properties, a wide range of adjustable mechanical properties, good cold resistance and flexibility, low-temperature curing capability, and environmental friendliness. They are widely used as binder resins in water-based inks and have broad application prospects in plastic film packaging, paper printing, and textile printing.

[0003] Currently available waterborne polyurethane inks cannot simultaneously meet the combined requirements of printing processes for color performance, substrate compatibility, and coating durability. Specifically, the molecular chains of traditional waterborne polyurethane dispersions are mainly composed of polyester, polyether, or polycarbonate structures, resulting in weak interactions with organic pigments or dyes. Furthermore, during ink preparation and storage, pigment particles are prone to flocculation and sedimentation, affecting color development. Simultaneously, during high-speed printing, the contact time between the ink and the substrate is extremely short, and the binder resin cannot quickly reduce the dynamic surface tension, leading to poor ink spreadability and wettability. In addition, existing waterborne polyurethane dispersion inks exhibit peeling and flaking issues in humid environments or after post-processing. Introducing epoxy resins, silane coupling agents, or acrylates can improve adhesion, but this reduces flexibility.

[0004] Therefore, there is an urgent need for a new type of waterborne polyurethane dispersion ink that simultaneously improves color development, wetting, and adhesion. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an aqueous polyurethane dispersion, its preparation method, and its application in water-based inks, thus solving the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, an aqueous polyurethane dispersion is provided, comprising, by weight parts, 50-70 parts of polycarbonate diol, 10-30 parts of polyester diol, 15-25 parts of diisocyanate, 2-8 parts of epoxy resin, 1-5 parts of aminated cage-type silsesquioxane, 3-6 parts of dimethylolpropionic acid, 1-4 parts of hydroxyl silicone oil, 2-5 parts of amino acid ring-opening epoxy resin adduct, 0.5-2 parts of crosslinking agent, 2-4 parts of post-chain extender, 2-5 parts of neutralizer, and an appropriate amount of water.

[0007] Preferably, the polycarbonate diol has a molecular weight of 1000-3000; The molecular weight of the polyester diol is 500-2000; The molecular weight of the hydroxyl silicone oil is 1000~2000.

[0008] Preferably, the crosslinking agent is selected from at least one of trimethylolpropane, glycerol, pentaerythritol, and bis(trimethylolpropane); The chain extender is selected from at least one of sodium ethylenediaminoethanesulfonate and sodium N-(2-aminoethyl)-2-aminoethanesulfonate. The neutralizing agent is selected from triethylamine.

[0009] According to a second aspect of the present invention, a method for preparing an aqueous polyurethane dispersion is provided, comprising the following steps: S1. Under a nitrogen atmosphere, polycarbonate diol, polyester diol, epoxy resin, and amino acid ring-opening epoxy resin adduct are mixed, vacuum dehydrated, and then diisocyanate and catalyst are added to carry out the first reaction until the NCO content reaches the theoretical value. Finally, dimethylolpropionic acid and hydroxyl silicone oil are added to carry out the second reaction to obtain the prepolymer. S2. Add a crosslinking agent to the prepolymer for chain extension and crosslinking, then add an amino-modified cage-type silsesquioxane and carry out a third reaction for grafting modification. S3. Triethylamine is added to the reaction system to neutralize the reaction, and then water is added to perform shear emulsification to obtain an emulsion. S4. Add a chain extender to the emulsion to carry out a chain extension reaction, reduce pressure, filter and discharge to obtain an aqueous polyurethane dispersion.

[0010] In step S1 of this application, the amount of catalyst used is 0.05 to 0.1% of the total amount of polycarbonate diol, polyester diol, epoxy resin and amino acid ring-opening epoxy resin adduct, and the catalyst can be selected from dibutyltin dilaurate. The amount of water added in step S3 is not limited, and excess water can be added. After depressurization in step S4, an aqueous polyurethane dispersion with a solid content of 35-45% is obtained.

[0011] Preferably, in step S1, the amino acid ring-opening epoxy resin adduct is obtained by reacting amino acids with aliphatic monoepoxy resin in an aqueous ethanol solution under the catalysis of triethylamine to obtain a compound with a hydroxyl functionality ≥2.

[0012] Preferably, the molar ratio of the amino acid to the aliphatic monoepoxy resin is 1:2.1~2.2.

[0013] Preferably, the reaction temperature is 55~65℃ and the time is 7~9h.

[0014] Preferably, in step S1, the temperature of the vacuum dehydration is 110~120℃ and the time is 1~2h; The temperature of the first reaction is 70~80℃, and the time is 2~3h; The second reaction is carried out at a temperature of 70-80°C for 2-3 hours.

[0015] Preferably, in step S2, the temperature of the third reaction is 60~70℃ and the time is 1~2h; In step S3, the neutralization reaction is carried out at a temperature of 40-50°C for 15-30 minutes. In step S4, the chain extension reaction takes 30 to 60 minutes.

[0016] According to a third aspect of the present invention, an application of an aqueous polyurethane dispersion in water-based inks is provided.

[0017] This invention provides an aqueous polyurethane dispersion, its preparation method, and its application in water-based inks. It offers the following advantages: (1) The waterborne polyurethane dispersion provided in this solution is modified by epoxy resin, hydroxyl silicone oil and aminated cage-type silsesquioxane to form a triple interpenetrating network structure. The epoxy resin and polyurethane segments undergo ring-opening reaction to form chemical crosslinking points, which improves the adhesion of the coating to the substrate. The hydroxyl silicone oil reduces the surface tension and improves the wetting and spreading properties.

[0018] (2) The waterborne polyurethane dispersion provided by this solution introduces amino acid ring-opening epoxy resin adducts into the polyurethane main chain, so that it contains both carboxyl and tertiary amine groups. On the one hand, it can enhance the binding force with pigment particles, and on the other hand, it can prevent flocculation. Therefore, it has excellent affinity and color development properties for both organic and inorganic pigments.

[0019] (3) The waterborne polyurethane dispersion provided by this solution is compounded with polycarbonate diol and polyester diol in a specific ratio. Through the synergistic effect of the two, the waterborne polyurethane dispersion can have both excellent color development base and adhesion.

[0020] (4) The waterborne polyurethane dispersion provided by this solution introduces sulfonate groups on the polyurethane matrix to improve the water resistance of the emulsion, while making the particle size distribution narrower and improving pigment wetting and color development.

[0021] (5) The waterborne polyurethane dispersion provided in this solution has a color difference ΔE<1.5, color saturation can be increased by more than 20%, the coating surface on PP and PE substrates can be reduced to below 32mN / m, the contact angle is <40°, the leveling is good, there are no pinhole defects, and the adhesion reaches level 0. Detailed Implementation

[0022] To better illustrate the content of this invention, the following description is provided in conjunction with specific embodiments.

[0023] Example 1 This embodiment provides an aqueous polyurethane dispersion, which, by mass parts, comprises 60 parts of polycarbonate diol with a molecular weight of 2000, 20 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 5 parts of epoxy resin E-44, 3 parts of aminated cage-type silsesquioxane, 4.5 parts of dimethylolpropionic acid, 2 parts of hydroxyl silicone oil with a molecular weight of 1500, 3 parts of amino acid ring-opening epoxy resin adduct, 1 part of trimethylolpropane, 3 parts of sodium ethylenediamine ethanesulfonate, and 3.4 parts of triethylamine. The specific preparation steps are as follows: Step 1: Under a nitrogen atmosphere, polycarbonate diol, polyester diol, epoxy resin, and amino acid ring-opening epoxy resin adduct are added to a reactor and dehydrated under vacuum at 110°C for 1 hour. Then, diisocyanate and 0.088 parts of catalyst are added, and the reaction is carried out at 80°C for 2.5 hours until the NCO content of the system reaches the theoretical value. Finally, dimethylolpropionic acid and hydroxyl silicone oil are added, and the reaction is carried out at 80°C for 2 hours to obtain the prepolymer. Step 2: Add a crosslinking agent to the prepolymer and perform a chain extension and crosslinking reaction at 80°C for 1 hour. Then add an amino-modified cage-type silsesquioxane and react at 70°C for 1 hour to graft POSS onto the polyurethane molecular chain. Step 3: Add triethylamine to the reaction system and neutralize it at 40°C for 15 min. Then add deionized water under high-speed shear conditions for emulsification and dispersion. Step 4: Add sodium ethylenediamine ethanesulfonate to the emulsion and perform chain extension treatment for 30 min. Then, reduce the pressure, filter and discharge the material to obtain an aqueous polyurethane dispersion with a solid content of 40%.

[0024] Example 2 The preparation method of this embodiment is the same as that of Example 1, except that the aqueous polyurethane dispersion, by mass parts, includes 70 parts of polycarbonate diol with a molecular weight of 2000, 10 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 5 parts of epoxy resin E-44, 3 parts of aminated cage-type silsesquioxane, 4.5 parts of dimethylolpropionic acid, 2 parts of hydroxyl silicone oil with a molecular weight of 1500, 3 parts of amino acid ring-opening epoxy resin adduct, 1 part of trimethylolpropane, 3 parts of sodium ethylenediamine ethanesulfonate, and 3.4 parts of triethylamine.

[0025] Example 3 The preparation method of this embodiment is the same as that of Example 1, except that the aqueous polyurethane dispersion, by mass parts, includes 50 parts of polycarbonate diol with a molecular weight of 2000, 30 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 5 parts of epoxy resin E-44, 3 parts of aminated cage-type silsesquioxane, 4.5 parts of dimethylolpropionic acid, 2 parts of hydroxyl silicone oil with a molecular weight of 1500, 3 parts of amino acid ring-opening epoxy resin adduct, 1 part of trimethylolpropane, 3 parts of sodium ethylenediamine ethanesulfonate, and 3.4 parts of triethylamine.

[0026] Comparative Example 1 The comparative example is prepared in the same way as Example 1, except that it includes 60 parts of polycarbonate diol with a molecular weight of 2000, 20 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 3 parts of aminated cage-type silsesquioxane, 4.5 parts of dimethylolpropionic acid, 2 parts of hydroxyl silicone oil with a molecular weight of 1500, 3 parts of amino acid ring-opening epoxy resin adduct, 1 part of trimethylolpropane, 3 parts of sodium ethylenediamine ethanesulfonate, and 3.4 parts of triethylamine.

[0027] Comparative Example 2 The comparative example is prepared in the same way as Example 1, except that it includes 60 parts of polycarbonate diol with a molecular weight of 2000, 20 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 5 parts of epoxy resin E-44, 3 parts of aminated cage-type silsesquioxane, 4.5 parts of dimethylolpropionic acid, 3 parts of amino acid ring-opening epoxy resin adduct, 1 part of trimethylolpropane, 3 parts of sodium ethylenediamine ethanesulfonate, and 3.4 parts of triethylamine.

[0028] Comparative Example 3 The comparative example is prepared using the same method as Example 1, except that it includes 60 parts of polycarbonate diol with a molecular weight of 2000, 20 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 5 parts of epoxy resin E-44, 3 parts of aminated cage-type silsesquioxane, 4.5 parts of dimethylolpropionic acid, 2 parts of hydroxyl silicone oil with a molecular weight of 1500, 1 part of trimethylolpropane, 3 parts of sodium ethylenediamine ethanesulfonate, and 3.4 parts of triethylamine.

[0029] Comparative Example 4 The comparative example is prepared in the same way as Example 1, except that it includes 60 parts of polycarbonate diol with a molecular weight of 2000, 20 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 5 parts of epoxy resin E-44, 4.5 parts of dimethylolpropionic acid, 2 parts of hydroxyl silicone oil with a molecular weight of 1500, 3 parts of amino acid ring-opening epoxy resin adduct, 1 part of trimethylolpropane, 3 parts of sodium ethylenediamine ethanesulfonate, and 3.4 parts of triethylamine.

[0030] Comparative Example 5 The comparative example is prepared in the same way as Example 1, except that it includes 60 parts of polycarbonate diol with a molecular weight of 2000, 20 parts of polybutylene adipate diol with a molecular weight of 1000, 18 parts of isophorone diisocyanate, 5 parts of hexamethylene diisocyanate, 5 parts of epoxy resin E-44, 3 parts of aminated cage-type silsesquioxane, 4.5 parts of dimethylolpropionic acid, 2 parts of hydroxyl silicone oil with a molecular weight of 1500, 3 parts of amino acid ring-opening epoxy resin adduct, 1 part of trimethylolpropane, and 3.4 parts of triethylamine.

[0031] The waterborne polyurethane dispersions prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were formulated into waterborne inks by adding 15% phthalocyanine blue pigment, and the performance was tested. The test results are shown in Table 1.

[0032] Color development and color difference tests were conducted by comparing the color with a standard color chart. The contact angle of the PE substrate surface was tested using a contact angle measuring instrument. Adhesion testing was conducted according to the testing standard GB / T 9286-1998; Glossiness was tested according to the test standard GB / T 9754-2007; Water resistance was tested by immersing the sample in deionized water for 24 hours.

[0033] Table 1

[0034] According to the test data in Table 1, the color difference ΔE in Examples 1-3 is between 1.2 and 1.4, indicating excellent color development. However, in Comparative Example 3, which did not contain the amino acid ring-opening epoxy resin adduct, the color difference ΔE was significantly increased. This is because the introduction of carboxyl and tertiary amine groups into the amino acid ring-opening epoxy resin adduct enhances the affinity between the resin and the phthalocyanine blue pigment, effectively preventing pigment flocculation. In Comparative Example 1, the absence of epoxy resin E-44 had little impact on color development. However, in Comparative Example 2, the absence of hydroxyl silicone oil led to increased surface tension, reduced pigment wetting and dispersion, and consequently, decreased color development performance. The contact angles in Examples 1 to 3 were 38 to 40°. In Comparative Example 2, which lacked silicone oil, the contact angle was as high as 67°, indicating that the addition of hydroxyl silicone oil could significantly reduce the surface energy of the coating. In Comparative Example 3, even without the addition of amino acid ring-opening epoxy resin adduct, the contact angle also increased slightly, indicating that the molecular polarity in the amino acid ring-opening epoxy resin adduct also reduced the surface energy of the coating. The adhesion in Examples 1 to 3 remained at level 0. However, in Comparative Examples 1, 2 and 4, which did not contain epoxy resin E-44, hydroxyl silicone oil and aminated cage-type silsesquioxane, the adhesion decreased significantly. This indicates that by modifying the coating with epoxy resin, hydroxyl silicone oil and aminated cage-type silsesquioxane to form a triple interpenetrating network structure, the adhesion of the coating to the substrate is significantly improved. After soaking for 24 hours, the waterborne polyurethane dispersions in Examples 1 and 2 exhibited excellent water resistance. This is because the cross-linking network can restrict the penetration of water molecules. If the proportion of polyester diol increases, the ester bonds of the polyester segments are easily hydrolyzed, leading to a decrease in water resistance and a slight whitening phenomenon. In Comparative Example 5, the absence of sodium ethylenediamine ethanesulfonate resulted in insufficient cross-linking density and a lack of sulfonic acid groups to stabilize the emulsion. After film formation, the carboxylic acid groups were concentratedly exposed, leading to a significant increase in water absorption and a significant decrease in water resistance.

[0035] In summary, through the comparison of the above embodiments and comparative examples, it can be seen that this application achieves simultaneous optimization of color development, wettability and adhesion through the synergistic effect of each component.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An aqueous polyurethane dispersion, characterized in that: By weight, it includes 50-70 parts of polycarbonate diol, 10-30 parts of polyester diol, 15-25 parts of diisocyanate, 2-8 parts of epoxy resin, 1-5 parts of aminated cage-type silsesquioxane, 3-6 parts of dimethylolpropionic acid, 1-4 parts of hydroxyl silicone oil, 2-5 parts of amino acid ring-opening epoxy resin adduct, 0.5-2 parts of crosslinking agent, 2-4 parts of post-chain extender, 2-5 parts of neutralizer, and an appropriate amount of water.

2. The aqueous polyurethane dispersion according to claim 1, characterized in that: The molecular weight of the polycarbonate diol is 1000~3000; The molecular weight of the polyester diol is 500-2000; The molecular weight of the hydroxyl silicone oil is 1000~2000.

3. The aqueous polyurethane dispersion according to claim 1, characterized in that: The crosslinking agent is selected from at least one of trimethylolpropane, glycerol, pentaerythritol, and bis(trimethylolpropane). The chain extender is selected from at least one of sodium ethylenediaminoethanesulfonate and sodium N-(2-aminoethyl)-2-aminoethanesulfonate. The neutralizing agent is selected from triethylamine.

4. A method for preparing the aqueous polyurethane dispersion according to any one of claims 1 to 3, characterized in that: Includes the following steps: S1. Under a nitrogen atmosphere, polycarbonate diol, polyester diol, epoxy resin, and amino acid ring-opening epoxy resin adduct are mixed, vacuum dehydrated, and then diisocyanate and catalyst are added to carry out the first reaction until the NCO content reaches the theoretical value. Finally, dimethylolpropionic acid and hydroxyl silicone oil are added to carry out the second reaction to obtain the prepolymer. S2. Add a crosslinking agent to the prepolymer for chain extension and crosslinking, then add an amino-modified cage-type silsesquioxane and carry out a third reaction for grafting modification. S3. Triethylamine is added to the reaction system to neutralize the reaction, and then water is added to perform shear emulsification to obtain an emulsion. S4. Add a chain extender to the emulsion to carry out a chain extension reaction, reduce pressure, filter and discharge to obtain an aqueous polyurethane dispersion.

5. The method for preparing an aqueous polyurethane dispersion according to claim 4, characterized in that: In step S1, the amino acid ring-opening epoxy resin adduct is obtained by reacting amino acids with aliphatic monoepoxy resin in an aqueous ethanol solution under the catalysis of triethylamine to obtain a compound with a hydroxyl functionality ≥2.

6. The method for preparing an aqueous polyurethane dispersion according to claim 5, characterized in that: The molar ratio of the amino acid to the aliphatic monoepoxy resin is 1:2.1~2.

2.

7. The method for preparing an aqueous polyurethane dispersion according to claim 5, characterized in that: The reaction is carried out at a temperature of 55-65°C for 7-9 hours.

8. The method for preparing an aqueous polyurethane dispersion according to claim 4, characterized in that: In step S1, the vacuum dehydration temperature is 110~120℃ and the time is 1~2h; The temperature of the first reaction is 70~80℃, and the time is 2~3h; The second reaction is carried out at a temperature of 70-80°C for 2-3 hours.

9. The method for preparing an aqueous polyurethane dispersion according to claim 4, characterized in that: In step S2, the temperature of the third reaction is 60~70℃ and the time is 1~2h; In step S3, the neutralization reaction is carried out at a temperature of 40-50°C for 15-30 minutes. In step S4, the chain extension reaction takes 30 to 60 minutes.

10. The application of an aqueous polyurethane dispersion according to any one of claims 1 to 3 or an aqueous polyurethane dispersion obtained by the preparation method according to any one of claims 4 to 9 in water-based inks.

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