A modified environmentally friendly water-based polyurethane ink and its preparation method

Abstract

This invention relates to the field of ink technology and discloses a modified environmentally friendly waterborne polyurethane ink and its preparation method. This waterborne polyurethane ink is formed by ball milling and mixing waterborne polyurethane resin as a base material. Because this polyurethane ink does not contain organic solvents, it possesses environmentally friendly characteristics, conforming to environmental protection principles. Furthermore, the added excipients can undergo ring-opening addition with the carboxyl groups of the chain extenders in the waterborne polyurethane resin structure, achieving cross-linking of the polyurethane molecular chains. On one hand, utilizing the inherent properties of the excipients, the path of water penetration can be extended, creating a barrier effect and improving the water resistance of the ink. Moreover, the excipients can form cross-linked structures with the polyurethane molecular chains. Therefore, the abundant siloxane structures and cross-linked structures in the excipient structure can also improve the stability of the ink, positively impacting its hydrophobicity and high-temperature resistance, thereby further expanding the application range of waterborne polyurethane inks.

Description

Technical Field

[0001] This invention relates to the field of ink technology, specifically to a modified environmentally friendly waterborne polyurethane ink and its preparation method. Background Technology

[0002] Ink is an essential material used in printing, transferring patterns and text onto substrates through printing or inkjet printing. Classified by composition, inks mainly include water-based inks, solvent-based inks, UV inks, and electron beam curing inks. Each type of ink has its unique performance characteristics. Among them, water-based polyurethane inks have won praise from users for their excellent environmental friendliness, stable ink properties, high viscosity, and strong tinting strength. Especially in flexographic and gravure printing, their drying speed can match the printing speed, providing a strong guarantee for efficient production. Despite the many advantages of water-based polyurethane inks, there are still some areas that need improvement, such as poor water resistance and high-temperature resistance. This makes it difficult for water-based polyurethane inks to be used in food packaging materials that require resistance to boiling and high temperatures. Therefore, strengthening and modifying water-based polyurethane inks is of great significance for their further application.

[0003] In existing technologies, the adhesion of polyurethane to low-polarity substrates is improved by optimizing the type and ratio of its hard and soft segments through structural design, thereby controlling its hardness and flexibility. However, this modification method has little effect on improving the water resistance and high-temperature resistance of polyurethane, and in practice, it is difficult to achieve a significant reinforcing effect. Based on this, the present invention provides an environmentally friendly water-based polyurethane ink that can solve the problems existing in the prior art. Summary of the Invention

[0004] In order to solve the problems mentioned in the background art, the purpose of this invention is to provide a modified environmentally friendly waterborne polyurethane ink and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A modified environmentally friendly water-based polyurethane ink, comprising the following raw materials by weight:

[0007] The ingredients are: 40-55 parts waterborne polyurethane resin, 2-6.5 parts attapulgite modifier, 10-15 parts pigment, 1-2 parts wetting and dispersing agent, 0.5-1 part defoamer, 0.5-1.5 parts thickener, and 30-40 parts deionized water.

[0008] As a further aspect of the present invention, the method for preparing the waterborne polyurethane resin is as follows:

[0009] Step 1: According to the weight percentage, under the action of 0.1-0.2 parts of tin catalyst, use 20-25 parts of polyether polyol and 4-8 parts of diisocyanate to carry out a prepolymerization reaction to obtain the prepolymer material;

[0010] Step 2: Add 1-3 parts of hydrophilic chain extender to the prepolymer and carry out chain extension polymerization to obtain the chain extended polymer.

[0011] Step 3: Add the chain extender polymer to 50-60 parts of deionized water, and use 0.5-1 parts of amine chain extender to further extend the chain reaction, thereby obtaining waterborne polyurethane resin.

[0012] As a further embodiment of the present invention, the tin catalyst is dibutyltin dilaurate or stannous octoate; the polyether polyol is selected from polyester polyols or polyether polyols with a number average molecular weight of 2000-4000; the diisocyanate is selected from any one of toluene diisocyanate, isophorone diisocyanate, or cyclohexanedimethyl diisocyanate; the hydrophilic chain extender is 2,2-dimethylolpropionic acid; and the amine chain extender is selected from any one of ethylenediamine, hexamethylenediamine, or polyether amine.

[0013] As a further aspect of the present invention, the preparation method of the attapulgite modified material is as follows:

[0014] Step S1: Modify attapulgite using a silane coupling agent to obtain organic attapulgite.

[0015] Step S2: In an ethanol medium, using 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane as a linker, the organic attapulgite is further modified under the action of an alkaline catalyst. Then, a crosslinking agent is added to continuously replace the excess 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to obtain the modified attapulgite material.

[0016] As a further aspect of the present invention, the silane coupling agent is selected from any one of 3-bromopropyltrimethoxysilane, 3-bromopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, or 3-chloropropyltriethoxysilane.

[0017] As a further aspect of the present invention, the alkaline catalyst is sodium hydride.

[0018] As a further embodiment of the present invention, the crosslinking agent is prepared by using 2,3-dibromopropionic acid and glycidyl ether as raw materials through a condensation reaction.

[0019] As a further aspect of the present invention, the condensation reaction process requires the addition of dicyclohexylcarbodiimide and N-hydroxysuccinimide in a mass ratio of 1:0.3-0.4 for catalysis.

[0020] As a further aspect of the present invention, the pigment is carbon black or titanium dioxide.

[0021] A method for preparing a modified environmentally friendly waterborne polyurethane ink includes the following steps:

[0022] Step 1: Add waterborne polyurethane resin, wetting and dispersing agent and defoamer to deionized water, and mechanically stir to mix evenly to form a premix.

[0023] The second step is to add the attapulgite modifier, pigment, and thickener to the premix and ball mill them for 2 hours.

[0024] The beneficial effects of this invention are:

[0025] This invention utilizes a binder and a crosslinking agent to continuously link and polymerize attapulgite on its surface, modifying the attapulgite surface with a polymeric substance containing siloxane and epoxy substituents. During the subsequent high-temperature spraying of the ink, the epoxy substituents can undergo ring-opening addition with the carboxyl groups of the chain extender in the waterborne polyurethane resin structure, thereby achieving covalent bonding between attapulgite and the waterborne polyurethane resin. This not only solves the compatibility problem between attapulgite and the waterborne polyurethane resin but also forms a three-dimensional crosslinked network structure with attapulgite as the core, which is beneficial for the uniform dispersion of attapulgite in the ink. On one hand, the layered structure of attapulgite can extend the water penetration path, creating a barrier effect and improving the water resistance of the ink. On the other hand, the presence of the crosslinked network and a large number of siloxane structures can improve the stability of the ink, positively impacting its hydrophobicity and high-temperature resistance.

[0026] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is an infrared test image of the crosslinking agent. Detailed Implementation

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] The preparation methods of the waterborne polyurethane resin in the following examples and comparative examples are as follows:

[0031] Step 1: According to the weight percentage, add 20 parts of polytetrahydrofuran ether diol with a number average molecular weight of 2500, 6 parts of isophorone diisocyanate and 0.1 parts of dibutyltin dilaurate to the reactor and stir at 85°C for 4 hours to obtain the prepolymer.

[0032] Step 2: Add 2 parts of 2,2-dimethylolpropionic acid to the prepolymer and carry out chain extension polymerization for 3 hours. Add acetone to adjust the viscosity to obtain the chain extension polymer.

[0033] Step 3: Stop heating and wait for the chain extender polymer to cool to room temperature. Add the chain extender polymer to 60 parts of deionized water and 0.8 parts of ethylenediamine. Further chain extend reaction at 50°C for 2 hours. Remove acetone by vacuum to obtain waterborne polyurethane resin.

[0034] Example 1

[0035] A modified environmentally friendly water-based polyurethane ink, comprising the following raw materials by weight:

[0036] 40 parts waterborne polyurethane resin, 2 parts attapulgite modifier, 10 parts pigment carbon black, 1 part wetting and dispersing agent, 0.5 parts defoamer, 0.5 parts thickener, and 30 parts deionized water.

[0037] The preparation method of the environmentally friendly water-based polyurethane ink includes the following steps:

[0038] Step 1: Add waterborne polyurethane resin, wetting and dispersing agent and defoamer to deionized water, and mechanically stir to mix evenly to form a premix.

[0039] The second step is to add the attapulgite modifier, pigment carbon black, and thickener to the premix and ball mill them for 2 hours.

[0040] The wetting and dispersing agent used is BYK-190; the defoamer used is TEGO Foamex 810; the thickener used is sodium alginate; the following are the same.

[0041] Example 2

[0042] A modified environmentally friendly water-based polyurethane ink, comprising the following raw materials by weight:

[0043] The mixture contains 45 parts of waterborne polyurethane resin, 6 parts of attapulgite modifier, 12 parts of pigment carbon black, 1.5 parts of wetting and dispersing agent, 0.6 parts of defoamer, 1 part of thickener, and 35 parts of deionized water.

[0044] The preparation method of the environmentally friendly water-based polyurethane ink includes the following steps:

[0045] Step 1: Add waterborne polyurethane resin, wetting and dispersing agent and defoamer to deionized water, and mechanically stir to mix evenly to form a premix.

[0046] The second step is to add the attapulgite modifier, pigment carbon black, and thickener to the premix and ball mill them for 2 hours.

[0047] Example 3

[0048] A modified environmentally friendly water-based polyurethane ink, comprising the following raw materials by weight:

[0049] The mixture contains 55 parts of waterborne polyurethane resin, 6.5 parts of attapulgite modifier, 15 parts of pigment carbon black, 2 parts of wetting and dispersing agent, 1 part of defoamer, 1.5 parts of thickener, and 40 parts of deionized water.

[0050] The preparation method of the environmentally friendly water-based polyurethane ink includes the following steps:

[0051] Step 1: Add waterborne polyurethane resin, wetting and dispersing agent and defoamer to deionized water, and mechanically stir to mix evenly to form a premix.

[0052] The second step is to add the attapulgite modifier, pigment carbon black, and thickener to the premix and ball mill them for 2 hours.

[0053] The attapulgite modified material in the above embodiments was prepared using the following method:

[0054] Step S1: 2.4g of attapulgite is ultrasonically dispersed in a 70% (v / v) ethanol aqueous solution, followed by the addition of 1.6g of 3-chloropropyltriethoxysilane. The mixture is stirred until homogeneous, heated to 70°C, stirred for 6 hours, cooled and discharged, centrifuged to obtain solid material, washed, and vacuum dried to obtain organic attapulgite.

[0055] Step S2: Add 1.5g of organic attapulgite to a 60% (v / v) ethanol aqueous solution and sonicate at 100kHz for 30min. Then add 4.5g of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane and 0.2g of sodium hydride. After the addition is complete, heat to 70℃ and keep warm for 4h. Then add 3g of crosslinking agent and raise the temperature to 90℃. Stir continuously for 16h, then stop heating, cool down and discharge the material. Centrifuge to obtain solid material, wash and vacuum dry to obtain modified attapulgite material.

[0056] In the above scheme, attapulgite is first modified with the silane coupling agent 3-chloropropyltriethoxysilane to obtain organic attapulgite with surface-modified halogen substituents. Then, under the action of the alkaline catalyst sodium hydride, the hydroxyl group in the structure of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane is first substituted with the halogen of the organic attapulgite, and the other end is substituted with the halogen in the structure of the crosslinking agent. By adding an excess of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, the remaining unreacted 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane and the crosslinking agent undergo continuous substitution and linking on the surface of attapulgite, thereby modifying the surface of attapulgite with a polymeric substance containing siloxane and epoxy substituents.

[0057] The preparation method of the crosslinking agent is as follows:

[0058] 0.6 g of 2,3-dibromopropionic acid and tetrahydrofuran were added to a nitrogen-filled reactor and stirred until a homogeneous reaction solution was formed. Then, 0.2 g of dicyclohexylcarbodiimide and 0.06 g of N-hydroxysuccinimide were added to the reactor and stirred at 40 °C for 1 h. Then, 0.2 g of glycidyl was added and the temperature was raised to 50 °C. After reacting for 4 h, the solvent was removed by rotary evaporation and the product was purified.

[0059] Figure 1 This is the infrared spectrum of the crosslinking agent, where 1722 cm⁻¹ is the focal length. -1 The characteristic absorption peak appearing at 908 cm⁻¹ is attributed to the characteristic absorption peak of the carbon-oxygen double bond of the ester group. -1 The characteristic absorption peak appearing at 512 cm⁻¹ is attributed to the characteristic absorption peak of the epoxy group. -1 The characteristic absorption peak appearing at the point is attributed to the C-Br characteristic absorption peak. No obvious hydroxyl characteristic absorption peak appears in the figure, indicating that the carboxyl group in the 2,3-dibromopropionic acid structure has undergone a condensation reaction with the carboxyl group in the glycidyl structure.

[0060] Comparative Example 1

[0061] A modified environmentally friendly water-based polyurethane ink, comprising the following raw materials by weight:

[0062] The mixture contains 45 parts waterborne polyurethane resin, 6 parts attapulgite clay, 12 parts pigment carbon black, 1.5 parts wetting and dispersing agent, 0.6 parts defoamer, 1 part thickener, and 35 parts deionized water.

[0063] The preparation method of the environmentally friendly water-based polyurethane ink includes the following steps:

[0064] Step 1: Add waterborne polyurethane resin, wetting and dispersing agent and defoamer to deionized water, and mechanically stir to mix evenly to form a premix.

[0065] The second step is to add attapulgite clay, pigment carbon black, and thickener to the premix and ball mill them for 2 hours.

[0066] Comparative Example 2

[0067] A modified environmentally friendly water-based polyurethane ink, comprising the following raw materials by weight:

[0068] The mixture contains 45 parts of waterborne polyurethane resin, 12 parts of pigment carbon black, 1.5 parts of wetting and dispersing agent, 0.6 parts of defoamer, 1 part of thickener, and 35 parts of deionized water.

[0069] The preparation method of the environmentally friendly water-based polyurethane ink includes the following steps:

[0070] Step 1: Add waterborne polyurethane resin, wetting and dispersing agent and defoamer to deionized water, and mechanically stir to mix evenly to form a premix.

[0071] The second step is to add pigment carbon black and thickener to the premix and ball mill them for 2 hours.

[0072] Test Case

[0073] The inks used in the examples and comparative examples were sprayed at high temperature onto the surface of a PET substrate to form test samples.

[0074] A. Soak the sample to be tested in water, take it out after 3 days, and observe the phenomenon on the surface of the ink;

[0075] B. Place the sample to be tested in an oven, adjust the temperature to 150℃, heat treat for 24 hours, and then take it out to observe the surface phenomenon.

[0076] The test results are recorded in the table below:

[0077]

[0078]

[0079] Analysis of the test results shows that when attapulgite is used alone as an additive, it is difficult to form a uniform and stable dispersion effect due to poor compatibility with water-based polyurethane resin, and thus cannot produce an effective barrier effect. As a result, the water resistance of the prepared ink is significantly reduced compared to the example, and the ink loses its siloxane and cross-linking structure, resulting in a significant reduction in the high temperature resistance of the ink.

[0080] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified environmentally friendly waterborne polyurethane ink, characterized in that, By weight, it includes the following ingredients: 40-55 parts of waterborne polyurethane resin, 2-6.5 parts of attapulgite modifier, 10-15 parts of pigment, 1-2 parts of wetting and dispersing agent, 0.5-1 part of defoamer, 0.5-1.5 parts of thickener, and 30-40 parts of deionized water; The preparation method of the attapulgite soil modifier is as follows: Step S1: Modify attapulgite using a silane coupling agent to obtain organic attapulgite. Step S2: In ethanol medium, using 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane as a linker, the organic attapulgite is further modified under the action of an alkaline catalyst. Then, a crosslinking agent is added to continuously replace the excess 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to obtain the modified attapulgite material. The crosslinking agent is prepared by using 2,3-dibromopropionic acid and glycidyl ether as raw materials through a condensation reaction.

2. The modified environmentally friendly waterborne polyurethane ink according to claim 1, characterized in that, The preparation method of the waterborne polyurethane resin is as follows: Step 1: According to the weight percentage, under the action of 0.1-0.2 parts of tin catalyst, use 20-25 parts of polyether polyol and 4-8 parts of diisocyanate to carry out a prepolymerization reaction to obtain the prepolymer material; Step 2: Add 1-3 parts of hydrophilic chain extender to the prepolymer and carry out chain extension polymerization to obtain the chain extended polymer. Step 3: Add the chain extender polymer to 50-60 parts of deionized water, and use 0.5-1 parts of amine chain extender to further extend the chain reaction, thereby obtaining waterborne polyurethane resin.

3. The modified environmentally friendly waterborne polyurethane ink according to claim 2, characterized in that, The tin catalyst is dibutyltin dilaurate or stannous octoate; the polyether polyol is selected from polyester polyols or polyether polyols with a number average molecular weight of 2000-4000; the diisocyanate is selected from toluene diisocyanate, isophorone diisocyanate or cyclohexanedimethyl diisocyanate; the hydrophilic chain extender is 2,2-dimethylolpropionic acid; the amine chain extender is selected from ethylenediamine, hexamethylenediamine or polyether amine.

4. The modified environmentally friendly waterborne polyurethane ink according to claim 1, characterized in that, The silane coupling agent is selected from any one of 3-bromopropyltrimethoxysilane, 3-bromopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, or 3-chloropropyltriethoxysilane.

5. The modified environmentally friendly waterborne polyurethane ink according to claim 1, characterized in that, The alkaline catalyst is sodium hydride.

6. The modified environmentally friendly waterborne polyurethane ink according to claim 1, characterized in that, The condensation reaction requires the addition of dicyclohexylcarbodiimide and N-hydroxysuccinimide in a mass ratio of 1:0.3-0.4 for catalysis.

7. The modified environmentally friendly waterborne polyurethane ink according to claim 1, characterized in that, The pigment is carbon black or titanium dioxide.

8. A method for preparing the modified environmentally friendly waterborne polyurethane ink as described in claim 1, characterized in that, Includes the following steps: Step 1: Add waterborne polyurethane resin, wetting and dispersing agent and defoamer to deionized water, and mechanically stir to mix evenly to form a premix. The second step is to add the attapulgite modifier, pigment, and thickener to the premix and ball mill them for 2 hours.

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