High-shielding water-based ink and preparation method thereof

Abstract

The invention discloses water-based ink with high shielding property. The water-based ink is prepared from the following raw materials in parts by weight: 35-37 parts of diisocyanate, 41-43 parts of polyol, 6-7 parts of a micromolecular chain extender, 5-6 parts of a hydrophilic chain extender, 4-5 parts of modified micron talcum powder and 5-6 parts of modified hyperbranched polyester, wherein the modified hyperbranched polyester comprises a core and modified nano talcum powder coated on the surface of the core, and the core is carboxyl-terminated hyperbranched polyester. The invention also discloses a preparation method of the high-shielding water-based ink. The printing ink has good shielding performance, fluidity and mechanical performance, the good shielding performance can be obtained through one-time printing, a film layer is more uniform, a product can be lighter and thinner due to the fact that the thickness of a coating is reduced, and the technology for printing the printing ink on the mobile phone glass cover plate is greatly simplified.

Description

Technical Field

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

[0002] During the processing of mobile phone glass cover plates, it is often necessary to screen-print ink on one side to achieve the effects of protection and shielding. At present, the shielding effect of ink is often achieved by adding talcum powder. Generally, the content of talcum powder in ink is about 5wt%, and the shielding performance is not high. It is necessary to use ink for multi-layer overprinting to increase the shielding property. This process requires repeated screen printing and baking steps. During the printing turnover and baking process, foreign matter is easily adhered to cause defects. Multiple printing and baking are also prone to scratches and deformation of the substrate. Although increasing the content of talcum powder can increase the shielding property of ink, the content of talcum powder needs to be as high as 10wt% or more to achieve a complete shielding effect in one coating, which will greatly reduce the fluidity of the ink, and talcum powder is prone to uneven dispersion in the ink, which leads to burrs, bumps, uneven edges and other problems in the coating after screen printing. Summary of the invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a high-shielding water-based ink and a preparation method thereof. The ink of the present invention has good hiding power, fluidity and mechanical properties.

[0004] The invention provides a high-shielding water-based ink, wherein the raw materials thereof include, by weight: 35-37 parts of diisocyanate, 41-43 parts of polyol, 6-7 parts of small molecule chain extender, 5-6 parts of hydrophilic chain extender, 4-5 parts of modified micron talc powder, and 5-6 parts of modified hyperbranched polyester;

[0005] The modified hyperbranched polyester comprises: a core and modified nano talc powder coated on the surface of the core, and the core is a carboxyl-terminated hyperbranched polyester.

[0006] The above-mentioned carboxyl-terminated hyperbranched polyester can be purchased from the market, such as HyPer C10.

[0007] Preferably, the solvent of the water-based ink for screen printing is water, and the solid content thereof is 45-55 wt %.

[0008] Preferably, the particle size of the modified micron talc is 1-3 μm.

[0009] Preferably, the particle size of the modified nano talc is ≤20 nm.

[0010] Preferably, the modified micron talc powder and the modified nano talc powder are both talc powder grafted with amino groups.

[0011] Preferably, the modified micron talc powder and the modified nano talc powder are talc powder graft-modified with a silane coupling agent containing an amino group.

[0012] The amino group-containing silane coupling agent may be γ-aminopropyltriethoxysilane or the like.

[0013] Preferably, in the preparation process of the modified hyperbranched polyester, the carboxyl-terminated hyperbranched polyester, the modified nano-talc and water are uniformly dispersed, the pH is adjusted to 5.5-6, and a reaction is carried out to obtain the modified hyperbranched polyester.

[0014] Preferably, in the preparation process of the modified hyperbranched polyester, the reaction is carried out at 40-50° C. for 1-2 hours.

[0015] Preferably, in the preparation process of the modified hyperbranched polyester, the weight ratio of the carboxyl-terminated hyperbranched polyester to the modified nano-talc is 1:3-4.

[0016] Preferably, during the preparation of the modified hyperbranched polyester, the pH is adjusted to 5.5-6 using an aqueous sulfuric acid solution.

[0017] Preferably, the diisocyanate is at least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate.

[0018] Preferably, the polyol is at least one of polytetramethylene glycol and polyethylene glycol.

[0019] Preferably, the small molecule chain extender is at least one of 1,4-butanediol and ethylenediamine.

[0020] Preferably, the hydrophilic chain extender is at least one of dimethylol propionic acid and dimethylol butyric acid.

[0021] The present invention also proposes a method for preparing the above-mentioned high-opaque water-based ink, comprising the following steps: in an inert gas atmosphere, mixing a polyol, a hydrophilic chain extender, a diisocyanate, and an organic solvent, adding a catalyst, reacting, then adding a small molecule chain extender to continue the reaction, then adding modified micron talc and modified hyperbranched polyester, continuing the reaction, then adjusting the pH of the solution to neutral, adding water for emulsification, removing the organic solvent, and obtaining a high-opaque water-based ink.

[0022] The above-mentioned organic solvent may be acetone.

[0023] Preferably, the catalyst is dibutyltin dilaurate.

[0024] Preferably, a catalyst is added, the temperature is raised to 60-70° C., and the reaction is kept warm for 2-3 hours.

[0025] Preferably, a small molecule chain extender is added and the reaction is continued at 60-70° C. for 1-2 hours.

[0026] Preferably, the modified micron talc and the modified hyperbranched polyester are added and the reaction is continued at 60-70° C. for 1-2 hours.

[0027] The invention loads a nano talc layer on the surface of a carboxyl-terminated hyperbranched polyester to obtain a modified hyperbranched polyester by covalently bonding a carboxyl group and an amino group, and then utilizes the remaining amino groups on the nano talc to graft the modified hyperbranched polyester into polyurethane. The specific structure of the modified hyperbranched polyester can cooperate with the modified micron talc to greatly improve the shielding performance of the ink, and can avoid the problem of reduced ink fluidity caused by a high talc content, improve the fluidity of the ink, and avoid the problems of burrs, convex points, uneven edges, etc. on the coating after screen printing. In addition, the invention can also improve the mechanical properties of the ink coating by introducing the modified hyperbranched polyester.

[0028] Good hiding power can be obtained by printing once with the ink of the present invention, and the film layer is more uniform. The reduced thickness of the coating can make the product thinner and lighter, greatly simplifying the process of printing ink on mobile phone glass cover plates and improving the printing yield rate. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below through specific embodiments.

[0030] Example 1

[0031] A high-shielding water-based ink, the raw materials of which include, by weight: 37 parts of isophorone diisocyanate, 100041 parts of polytetramethylene glycol, 7 parts of ethylenediamine, 5 parts of dimethylolbutyric acid, 5 parts of γ-aminopropyltriethoxysilane-modified micron talc with a particle size of 1 μm, and 5 parts of modified hyperbranched polyester;

[0032] The modified hyperbranched polyester comprises: a core and γ-aminopropyltriethoxysilane modified nano talc powder coated on the surface of the core, wherein the core is a carboxyl-terminated hyperbranched polyester HyPer C10;

[0033] In the preparation process of the modified hyperbranched polyester, the terminal carboxyl hyperbranched polyester HyPer C10 aqueous dispersion and the modified nano talc aqueous dispersion (the modified nano talc is γ-aminopropyltriethoxysilane modified nano talc, and its particle size is ≤20nm) are mixed so that the weight ratio of the terminal carboxyl hyperbranched polyester and the modified nano talc is 1:3, and then the pH is adjusted to 6 with an aqueous sulfuric acid solution, reacted at 40°C for 2h, filtered, washed with water, and dried to obtain the modified hyperbranched polyester.

[0034] The preparation method of the above-mentioned high-opaque water-based ink comprises the following steps: adding polytetramethylene glycol 1000 and dihydroxymethylbutyric acid to acetone and mixing, then adding isophorone diisocyanate and mixing under nitrogen protection, then adding dibutyltin dilaurate, heating to 60°C and stirring to react for 3 hours, then adding ethylenediamine, continuing to react at 60°C for 2 hours, then adding modified micron talc and modified hyperbranched polyester, continuing to react at 60°C for 2 hours, then adding triethylamine to adjust the pH of the solution to neutral, adding water for emulsification, and removing acetone by reduced pressure evaporation to obtain a high-opaque water-based ink with a solid content of 45wt%.

[0035] Example 2

[0036] A high-shielding water-based ink, the raw materials of which include, by weight: 35 parts of dicyclohexylmethane diisocyanate, 43 parts of polyethylene glycol 1000, 6 parts of 1,4-butanediol, 6 parts of dimethylolpropionic acid, 4 parts of γ-aminopropyltriethoxysilane-modified micron talc with a particle size of 3 μm, and 6 parts of modified hyperbranched polyester;

[0037] The modified hyperbranched polyester comprises: a core and γ-aminopropyltriethoxysilane modified nano talc powder coated on the surface of the core, wherein the core is a carboxyl-terminated hyperbranched polyester HyPer C10;

[0038] In the preparation process of the modified hyperbranched polyester, a carboxyl-terminated hyperbranched polyester HyPer C10 aqueous dispersion and a modified nano-talc aqueous dispersion (the modified nano-talc is γ-aminopropyltriethoxysilane modified nano-talc with a particle size of ≤20 nm) are mixed so that the weight ratio of the carboxyl-terminated hyperbranched polyester to the modified nano-talc is 1:4, and then the pH is adjusted to 5.5 with a sulfuric acid aqueous solution, reacted at 50° C. for 1 h, filtered, washed with water, and dried to obtain the modified hyperbranched polyester.

[0039] The preparation method of the above-mentioned high-opaque water-based ink comprises the following steps: adding polyethylene glycol 1000 and dihydroxymethylpropionic acid to acetone and mixing, then adding dicyclohexylmethane diisocyanate and mixing under nitrogen protection, then adding dibutyltin dilaurate, heating to 70°C and stirring to react for 2 hours, then adding 1,4-butanediol, continuing to react at 70°C for 1 hour, then adding modified micron talc and modified hyperbranched polyester, continuing to react at 70°C for 1 hour, then adding triethylamine to adjust the pH of the solution to neutral, adding water for emulsification, and removing acetone by reduced pressure evaporation to obtain a high-opaque water-based ink with a solid content of 55wt%.

[0040] Example 3

[0041] A high-shielding water-based ink, the raw materials of which include, by weight: 36 parts of hexamethylene diisocyanate, 100021 parts of polytetramethylene glycol, 100021 parts of polyethylene glycol, 6 parts of 1,4-butanediol, 5 parts of dimethylol propionic acid, 5 parts of γ-aminopropyl triethoxysilane-modified micron talc with a particle size of 2 μm, and 6 parts of modified hyperbranched polyester;

[0042] The modified hyperbranched polyester comprises: a core and γ-aminopropyltriethoxysilane modified nano talc powder coated on the surface of the core, wherein the core is a carboxyl-terminated hyperbranched polyester HyPer C10;

[0043] In the preparation process of the modified hyperbranched polyester, the terminal carboxyl hyperbranched polyester HyPer C10 aqueous dispersion and the modified nano talc aqueous dispersion (the modified nano talc is γ-aminopropyltriethoxysilane modified nano talc, and its particle size is ≤20nm) are mixed so that the weight ratio of the terminal carboxyl hyperbranched polyester and the modified nano talc is 1:3, and then the pH is adjusted to 5.8 with a sulfuric acid aqueous solution, reacted at 45°C for 1.5h, filtered, washed with water, and dried to obtain the modified hyperbranched polyester.

[0044] The preparation method of the above-mentioned high-opaque water-based ink comprises the following steps: adding polytetramethylene ether glycol 1000, polyethylene glycol 1000, and dihydroxymethylpropionic acid to acetone and mixing, then adding hexamethylene diisocyanate and mixing under nitrogen protection, then adding dibutyltin dilaurate, heating to 65°C and stirring to react for 2.5 hours, then adding a small molecule chain extender, continuing to react at 65°C for 1.5 hours, then adding modified micron talc and modified hyperbranched polyester, continuing to react at 65°C for 1.5 hours, then adding triethylamine to adjust the pH of the solution to neutral, adding water for emulsification, and removing acetone by reduced pressure evaporation to obtain a high-opaque water-based ink with a solid content of 50wt%.

[0045] Comparative Example 1

[0046] An ink, wherein "6 parts of modified hyperbranched polyester" is replaced by "6 ​​parts of γ-aminopropyltriethoxysilane modified nano talc", and the rest is the same as Example 3.

[0047] Comparative Example 2

[0048] An ink, wherein "6 parts of modified hyperbranched polyester" is replaced by "1.5 parts of terminal carboxyl hyperbranched polyester HyPer C10", and the rest is the same as Example 3.

[0049] Comparative Example 3

[0050] An ink, wherein "6 parts of modified hyperbranched polyester" is replaced by "1.5 parts of terminal carboxyl hyperbranched polyester HyPer C10 and 4.5 parts of γ-aminopropyltriethoxysilane modified nano talc", and the rest is the same as Example 3.

[0051] Comparative Example 4

[0052] An ink, not containing modified hyperbranched polyester, and otherwise the same as in Example 3.

[0053] The inks of Examples 1-3 and Comparative Examples 1-4 were used to screen print coatings of the same thickness on the surface of a mobile phone glass cover plate in the same manner, and the coating properties were tested. The results are shown in Table 1.

[0054] Table 1 Test results

[0055] Test items Check whether the coating edge has burrs and is neat Is the coating completely covered? Tensile strength MPa Example 1 No burrs, neat edges Complete coverage 28.1 Example 2 No burrs, neat edges Complete coverage 27.8 Example 3 No burrs, neat edges Complete coverage 28.6 Comparative Example 1 There are many burrs, uneven edges, and bumps Complete coverage 19.6 Comparative Example 2 No burrs, neat edges Cannot completely cover 27.0 Comparative Example 3 There are many burrs and uneven edges Cannot completely cover 26.8 Comparative Example 4 No burrs, neat edges Cannot completely cover 19.8

[0056] It can be seen from Table 1 that the coating of the present invention has good hiding performance, the coating edge is burr-free and neat, and the coating has good mechanical properties.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A high-shielding water-based ink, characterized in that: The raw materials include, by weight: 35-37 parts of diisocyanate, 41-43 parts of polyol, 6-7 parts of small molecule chain extender, 5-6 parts of hydrophilic chain extender, 4-5 parts of modified micron talc, and 5-6 parts of modified hyperbranched polyester; The modified hyperbranched polyester comprises: a core and modified nano talc powder coated on the surface of the core, and the core is a carboxyl-terminated hyperbranched polyester.

2. The high-shielding water-based ink according to claim 1, characterized in that: The solvent of the water-based ink for screen printing is water, and the solid content thereof is 45-55 wt %.

3. The high-shielding water-based ink according to claim 1 or 2, characterized in that: The particle size of the modified micron talc powder is 1-3 μm; preferably, the particle size of the modified nano talc powder is ≤20 nm.

4. The high-shielding water-based ink according to any one of claims 1 to 3, characterized in that: The modified micron talc powder and the modified nano talc powder are both talc powder grafted with amino groups; preferably, the modified micron talc powder and the modified nano talc powder are both talc powder grafted with a silane coupling agent containing amino groups.

5. The high-shielding water-based ink according to any one of claims 1 to 4, characterized in that: In the preparation process of the modified hyperbranched polyester, the carboxyl-terminated hyperbranched polyester, the modified nano-talc powder and water are uniformly dispersed, the pH is adjusted to 5.5-6, and a reaction is carried out to obtain the modified hyperbranched polyester.

6. The high-shielding water-based ink according to claim 5, characterized in that: In the preparation process of the modified hyperbranched polyester, the reaction is carried out at 40-50° C. for 1-2 hours; preferably, in the preparation process of the modified hyperbranched polyester, the weight ratio of the terminal carboxyl hyperbranched polyester and the modified nano talc is 1:3-4; preferably, in the preparation process of the modified hyperbranched polyester, the pH is adjusted to 5.5-6 with an aqueous sulfuric acid solution.

7. The high-shielding water-based ink according to any one of claims 1 to 6, characterized in that: The diisocyanate is at least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate; preferably, the polyol is at least one of polytetramethylene glycol and polyethylene glycol.

8. The high-shielding water-based ink according to any one of claims 1 to 7, characterized in that: The small molecule chain extender is at least one of 1,4-butanediol and ethylenediamine; preferably, the hydrophilic chain extender is at least one of dimethylolpropionic acid and dimethylolbutyric acid.

9. A method for preparing a high-shielding water-based ink as claimed in any one of claims 1 to 8, characterized in that: The method comprises the following steps: in an inert gas atmosphere, mixing polyol, hydrophilic chain extender, diisocyanate and organic solvent, adding a catalyst, reacting, then adding a small molecule chain extender to continue the reaction, then adding modified micron talcum powder and modified hyperbranched polyester, continuing the reaction, then adjusting the pH value of the solution to neutral, adding water for emulsification, removing the organic solvent, and obtaining a highly opaque water-based ink.

10. The method for preparing a high-shielding water-based ink according to claim 9, characterized in that: The catalyst is dibutyltin dilaurate; preferably, the catalyst is added, the temperature is raised to 60-70°C, and the reaction is kept warm for 2-3 hours; preferably, a small molecule chain extender is added, and the reaction is continued at 60-70°C for 1-2 hours; preferably, modified micron talc and modified hyperbranched polyester are added, and the reaction is continued at 60-70°C for 1-2 hours.