Modified environment-friendly waterborne polyurethane ink and preparation method thereof

Abstract

The invention relates to the technical field of ink, and discloses modified environment-friendly water-based polyurethane ink and a preparation method thereof.The water-based polyurethane ink is formed by taking water-based polyurethane resin as a base material through ball milling and mixing, and due to the fact that the polyurethane ink does not contain an organic solvent, the water-based polyurethane ink has the environment-friendly characteristic and conforms to the environment-friendly concept; the added auxiliary material can be subjected to ring-opening addition with carboxyl of a chain extender in a waterborne polyurethane resin structure to realize crosslinking of a polyurethane molecular chain, on one hand, the self characteristics of the auxiliary material can be utilized to prolong a moisture permeation path, generate a barrier effect and improve the water resistance of the ink, and on the other hand, the auxiliary material can form a crosslinking structure with the polyurethane molecular chain, so that the water resistance of the ink is improved; therefore, a large number of siloxane structures and cross-linked structures in the auxiliary material structure can be utilized to improve the stability of the ink, and the hydrophobic property and high temperature resistance of the ink can be positively influenced, so that the application range of the waterborne polyurethane ink can be further widened.

Description

Technical Field

[0001] The invention relates to the technical field of inks, and in particular to a modified environmentally friendly water-based polyurethane ink and a preparation method thereof. Background Art

[0002] Ink is an important material used for printing. It prints or sprays patterns and texts on substrates. According to the composition, inks mainly include water-based inks, solvent-based inks, UV inks, electron beam curing inks, etc. Each ink has its own unique performance characteristics. Among them, water-based polyurethane inks have won praise from users for their excellent environmental protection, stable ink properties, high viscosity, and strong tinting strength. Especially in flexographic printing and gravure printing, its drying speed can match the printing speed, providing a strong guarantee for efficient production. Although water-based polyurethane inks have many advantages, there are still some areas that need to be improved, such as poor water resistance and high temperature resistance, which makes it difficult to use water-based polyurethane inks in the field of food packaging materials that require resistance to cooking and high temperature. Therefore, it is of great significance to enhance and modify water-based polyurethane inks for their further application.

[0003] In the prior art, the hardness and flexibility of polyurethane are regulated by optimizing the types and ratios of its soft and hard segments through structural design, thereby improving its adhesion on low-polarity substrates. However, this modification method has little effect on improving the water resistance and high temperature resistance of polyurethane, and it is actually difficult to achieve a significant enhancement 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 technology, the object of the present invention is to provide a modified environmentally friendly water-based polyurethane ink and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A modified environmentally friendly water-based polyurethane ink comprises the following raw materials in parts by weight:

[0007] 40-55 parts of waterborne polyurethane resin, 2-6.5 parts of attapulgite modified material, 10-15 parts of pigment, 1-2 parts of wetting and dispersing agent, 0.5-1 part of defoaming agent, 0.5-1.5 parts of thickener, and 30-40 parts of deionized water.

[0008] As a further embodiment of the present invention, the preparation method of the waterborne polyurethane resin is as follows:

[0009] Step 1: Under the action of 0.1 - 0.2 parts by weight of a tin catalyst, 20 - 25 parts of a polyether polyol and 4 - 8 parts of a diisocyanate are used for a prepolymerization reaction to obtain a prepolymer.

[0010] Step 2: 1 - 3 parts of a hydrophilic chain extender are added to the prepolymer for chain extension polymerization to obtain a chain - extended polymerization material.

[0011] Step 3: The chain - extended polymerization material is added to 50 - 60 parts of deionized water, and 0.5 - 1 part of an amine - type chain extender is used for further chain - extension reaction to obtain a water - borne polyurethane resin.

[0012] As a further scheme 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 cyclohexane dimethylene diisocyanate; the hydrophilic chain extender is 2,2 - bis(hydroxymethyl)propionic acid; the amine - type chain extender is selected from any one of ethylenediamine, hexamethylenediamine or polyetheramine.

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

[0014] Step S1: The attapulgite is modified with a silane coupling agent to obtain an organic attapulgite.

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

[0016] As a further scheme 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 scheme of the present invention, the basic catalyst is sodium hydride.

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

[0019] As a further scheme of the present invention, during the condensation reaction, dicyclohexylcarbodiimide and N - hydroxysuccinimide with a mass ratio of 1:0.3 - 0.4 are added for catalysis.

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

[0021] A preparation method of a modified environment-friendly waterborne polyurethane ink comprises the following steps:

[0022] First step, adding a waterborne polyurethane resin, a wetting dispersant and an antifoaming agent into deionized water, and mechanically stirring and mixing uniformly to form a premix.

[0023] Second step, adding an attapulgite modifier, a pigment and a thickener into the premix, and ball-milling and mixing for 2 h to obtain the ink.

[0024] Advantages of the present invention:

[0025] In the present invention, continuous linking polymerization is carried out on the surface of attapulgite by using a linker and a bridging agent, and a polymeric substance containing siloxane and epoxy substituents is modified on the surface of attapulgite. Among them, the epoxy substituent can carry out ring-opening addition with the carboxyl group of the chain extender in the structure of the waterborne polyurethane resin during the subsequent high-temperature spraying process of the ink, so as to realize the covalent connection between the attapulgite and the waterborne polyurethane resin. It can not only solve the compatibility problem between the attapulgite and the waterborne polyurethane resin, but also form a three-dimensional cross-linked network structure with the attapulgite as the core, which is beneficial to the uniform dispersion of the attapulgite in the ink. On the one hand, the layered structure of the attapulgite can extend the path of water penetration, produce a barrier effect, and improve the water resistance of the ink. On the other hand, the existence of the cross-linked network and a large number of siloxane structures can improve the stability of the ink, and have a positive impact on the hydrophobicity and high-temperature resistance of the ink.

[0026] Of course, it is not necessary for any product implementing the present invention to achieve all the above advantages simultaneously. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0028] Figure 1 It is an infrared test chart of the bridging agent. Detailed Embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

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

[0031] Step 1: According to the weight parts, add 20 parts of polytetrahydrofuran ether glycol with an average molecular weight of 2500, 6 parts of isophorone diisocyanate, and 0.1 part of dibutyltin dilaurate into a reaction kettle, and stir at a temperature of 85 °C for 4 h to obtain a prepolymer;

[0032] Step 2: Add 2 parts of 2,2-dimethylolpropionic acid into the prepolymer, carry out chain extension polymerization for 3 h, and add acetone to adjust the viscosity to obtain a chain extension polymerization material;

[0033] Step 3: Stop heating. After the chain extension polymerization material cools to room temperature, add the chain extension polymerization material into 60 parts of deionized water, and at the same time add 0.8 part of ethylenediamine. Further carry out chain extension reaction at a temperature of 50 °C for 2 h, and evacuate to remove acetone to obtain the waterborne polyurethane resin.

[0034] Example 1

[0035] A modified environmentally friendly waterborne polyurethane ink, according to the weight parts, comprises the following raw materials:

[0036] 40 parts of waterborne polyurethane resin, 2 parts of attapulgite modified material, 10 parts of pigment carbon black, 1 part of wetting and dispersing agent, 0.5 part of defoaming agent, 0.5 part of thickening agent, and 30 parts of deionized water.

[0037] The preparation method of the environmentally friendly waterborne polyurethane ink comprises the following steps:

[0038] The first step: Add the waterborne polyurethane resin, wetting and dispersing agent, and defoaming agent into deionized water, and mechanically stir and mix evenly to form a premix;

[0039] The second step: Add the attapulgite modified material, pigment carbon black, and thickening agent into the premix, and ball mill and mix for 2 h.

[0040] The wetting and dispersing agent is selected as BYK-190; the defoaming agent is selected as TEGO Foamex 810; the thickening agent is selected as sodium alginate; the same applies hereinafter.

[0041] Example 2

[0042] A modified environmentally friendly waterborne polyurethane ink, by weight, comprises the following raw materials:

[0043] 45 parts of waterborne polyurethane resin, 6 parts of attapulgite modified material, 12 parts of pigment carbon black, 1.5 parts of wetting and dispersing agent, 0.6 part of defoaming agent, 1 part of thickening agent, and 35 parts of deionized water.

[0044] The preparation method of the environmentally friendly waterborne polyurethane ink comprises the following steps:

[0045] First step, adding the waterborne polyurethane resin, wetting and dispersing agent, and defoaming agent into deionized water, and mechanically stirring and mixing evenly to form a premix;

[0046] Second step, adding the attapulgite modified material, pigment carbon black, and thickening agent into the premix, and ball milling and mixing for 2 h to obtain the product.

[0047] Example 3

[0048] A modified environmentally friendly waterborne polyurethane ink, by weight, comprises the following raw materials:

[0049] 55 parts of waterborne polyurethane resin, 6.5 parts of attapulgite modified material, 15 parts of pigment carbon black, 2 parts of wetting and dispersing agent, 1 part of defoaming agent, 1.5 parts of thickening agent, and 40 parts of deionized water.

[0050] The preparation method of the environmentally friendly waterborne polyurethane ink comprises the following steps:

[0051] First step, adding the waterborne polyurethane resin, wetting and dispersing agent, and defoaming agent into deionized water, and mechanically stirring and mixing evenly to form a premix;

[0052] Second step, adding the attapulgite modified material, pigment carbon black, and thickening agent into the premix, and ball milling and mixing for 2 h to obtain the product.

[0053] In the above examples, the attapulgite modified material is prepared by the following method:

[0054] Step S1, ultrasonically dispersing 2.4 g of attapulgite in an ethanol aqueous solution with a volume fraction of 70%, then adding 1.6 g of 3-chloropropyltriethoxysilane, stirring and mixing evenly, heating to 70 °C, stirring for 6 h, cooling and discharging, centrifuging to obtain a solid material, washing, and drying under vacuum to obtain organic attapulgite;

[0055] Step S2, add 1.5g of organic attapulgite to a 60% volume fraction ethanol aqueous solution medium, ultrasonically treat at an ultrasonic frequency of 100kHz for 30min, then add 4.5g of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane and 0.2g of sodium hydride, after the addition, heat to 70°C, keep warm for 4h, continue to add 3g of bridging agent, and raise the temperature to 90°C, continue stirring for 16h, stop heating, cool the material, centrifuge to obtain a solid material, wash, and vacuum dry to obtain a attapulgite modified material.

[0056] In the above scheme, the silane coupling agent 3-chloropropyltriethoxysilane is first used to modify the attapulgite to obtain an organic attapulgite with surface modified oil 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 replaced with the halogen of the organic attapulgite, and the other end is replaced with the halogen in the structure of the bridging agent. By adding an excess of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, the remaining 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane that does not participate in the reaction is continuously replaced and linked with the bridging agent on the surface of the attapulgite, thereby modifying the surface of the attapulgite with a polymeric substance containing siloxane and epoxy substituents.

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

[0058] 0.6 g of 2,3-dibromopropionic acid and tetrahydrofuran were added to a reactor filled with nitrogen, and stirring was started to form a uniform reaction liquid. Then, 0.2 g of dicyclohexylcarbodiimide and 0.06 g of N-hydroxysuccinimide were added to the reactor. After stirring at a temperature of 40°C for 1 hour, 0.2 g of glycidol was added, and the temperature was raised to 50°C. After reacting for 4 hours, the solvent was removed by rotary evaporation and purified to obtain the product.

[0059] Figure 1 This is the infrared test image of the bridging agent, where 1722cm -1 The characteristic absorption peak at 908cm is attributed to the carbon-oxygen double bond characteristic absorption peak of the ester group. -1 The characteristic absorption peak at 512 cm is attributed to the characteristic absorption peak of the epoxy group. -1 The characteristic absorption peak that appears at belongs to the C-Br characteristic absorption peak. There is no obvious hydroxyl characteristic absorption peak in the figure, which indicates that the carboxyl group in the 2,3-dibromopropionic acid structure undergoes a condensation reaction with the carboxyl group in the glycidol structure.

[0060] Comparative Example 1

[0061] A modified environmentally friendly water-based polyurethane ink comprises the following raw materials in parts by weight:

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

[0063] The preparation method of the environment-friendly waterborne polyurethane ink comprises the following steps:

[0064] First step, adding the waterborne polyurethane resin, the wetting and dispersing agent and the defoaming agent into the deionized water, and mechanically stirring and mixing uniformly to form a premix;

[0065] Second step, adding the attapulgite, the pigment carbon black and the thickener into the premix, and ball-milling and mixing for 2 h to obtain the product.

[0066] Comparative Example 2

[0067] A modified environment-friendly waterborne polyurethane ink, comprising the following raw materials in parts by weight:

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

[0069] The preparation method of the environment-friendly waterborne polyurethane ink comprises the following steps:

[0070] First step, adding the waterborne polyurethane resin, the wetting and dispersing agent and the defoaming agent into the deionized water, and mechanically stirring and mixing uniformly to form a premix;

[0071] Second step, adding the pigment carbon black and the thickener into the premix, and ball-milling and mixing for 2 h to obtain the product.

[0072] Test Example

[0073] Spraying the inks in the examples and comparative examples on the surface of a PET substrate at a high temperature to form a test sample to be tested;

[0074] A. Immersing the test sample to be tested in water, taking it out after 3 days, and observing the surface phenomenon of the ink;

[0075] B. Placing the test sample to be tested in an oven, adjusting the temperature to 150 °C, taking it out after heat treatment for 24 h, and observing the surface phenomenon;

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

[0077]

[0078]

[0079] Analysis of the test results shows that when attapulgite is used alone as an additive, due to poor compatibility with the waterborne polyurethane resin, it is difficult to form a uniform and stable dispersion effect, and an effective barrier effect cannot be produced. Therefore, the water resistance of the prepared ink is significantly reduced compared with that of the examples, and the siloxane and crosslinked structure are lost, resulting in a significant reduction in the high-temperature resistance of the ink.

[0080] In this article, specific examples are used to elaborate on the principles and implementation methods of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention, including the best mode, and also 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 for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention 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 the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of 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, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A modified environmentally friendly water-based polyurethane ink, characterized in that: According to weight parts, it includes the following raw materials: 40-55 parts of waterborne polyurethane resin, 2-6.5 parts of attapulgite modified material, 10-15 parts of pigment, 1-2 parts of wetting and dispersing agent, 0.5-1 part of defoaming agent, 0.5-1.5 parts of thickener, and 30-40 parts of deionized water.

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

3. The modified environmentally friendly water-based 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 polyol or polyether polyol with a number average molecular weight of 2000-4000; the diisocyanate is selected from any one of toluene diisocyanate, isophorone diisocyanate or cyclohexane dimethylene diisocyanate; the hydrophilic chain extender is 2,2-dihydroxymethyl propionic acid; the amine chain extender is selected from any one of ethylenediamine, hexamethylenediamine or polyetheramine.

4. The modified environmentally friendly water-based polyurethane ink according to claim 1, characterized in that: The preparation method of the attapulgite modified material is as follows: Step S1, modifying attapulgite with a silane coupling agent to obtain organic attapulgite; 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, and then a bridging agent is added to continuously replace with an excess of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to obtain a modified attapulgite material.

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

6. The modified environmentally friendly water-based polyurethane ink according to claim 4, characterized in that: The alkaline catalyst is sodium hydride.

7. The modified environmentally friendly water-based polyurethane ink according to claim 4, characterized in that: The bridging agent is prepared by using 2,3-dibromopropionic acid and glycidol as raw materials through a condensation reaction.

8. The modified environmentally friendly water-based polyurethane ink according to claim 7, characterized in that: During the condensation reaction, dicyclohexylcarbodiimide and N-hydroxysuccinimide in a mass ratio of 1:0.3-0.4 need to be added for catalysis.

9. The modified environmentally friendly water-based polyurethane ink according to claim 1, characterized in that: The pigment is carbon black or titanium dioxide.

10. A method for preparing the modified environmentally friendly water-based polyurethane ink as claimed in claim 1, characterized in that: The following steps are involved: The first step is to add waterborne polyurethane resin, wetting dispersant and defoamer into deionized water, and mechanically stir and mix them evenly to form a premix; The second step is to add the attapulgite modified material, pigment and thickener into the premix and mix by ball milling for 2 hours.

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