Preparation method of ink-absorbing filler and paper surface waterproof ink-absorbing coating emulsion

Abstract

The invention belongs to the technical field of functional coatings, and discloses an ink-absorbing filler and a preparation method of a paper surface waterproof ink-absorbing coating emulsion. The preparation method of the ink-absorbing filler comprises the following preparation steps: (1) carrying out surface modification on porous silicon dioxide micro-powder by adopting an epoxy silane coupling agent to obtain epoxy modified porous silicon dioxide micro-powder; and (2) heating and dissolving a cyclodextrin compound in an alkaline aqueous solution, then adding the epoxy group modified porous silicon dioxide micro powder in the step (1), carrying out heat preservation and stirring reaction, and filtering, washing and drying a product to obtain the cyclodextrin compound modified porous silicon dioxide ink-absorbing filler. The cyclodextrin compound is adopted to perform surface modification on the conventional silicon dioxide ink-absorbing filler, so that the stability and the ink-absorbing effect of the ink-absorbing filler in a matrix resin emulsion can be remarkably improved, and the structural strength and the water resistance of a coating and paper can be remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of functional coatings, and in particular relates to the preparation of an ink-absorbing filler and a waterproof ink-absorbing coating emulsion on the surface of paper. Background Art

[0002] In response to the call for de-plasticization of paper packaging, the traditional paper packaging laminating process has been gradually cancelled. However, single paper packaging is not water-resistant and is easily affected by moisture. After being affected by moisture, the structural strength of the paper packaging also deteriorates. In order to improve this situation, the process of applying plastic oil or varnish can be adopted. However, plastic oil or varnish can only be processed after printing, and the cost of single small batch processing is also relatively high. In order to solve this problem, paper ink-absorbing coating came into being. It can be pre-coated in large quantities during processing in the paper mill, which can greatly save resources and reduce overall costs. The surface of the paper after pre-coating with ink-absorbing coating does not affect printing, has ink absorbency, the coating has a certain water resistance, and can also increase the structural strength of the paper.

[0003] At present, the ink-absorbing coating of paper is mainly composed of polymer film-forming resin and porous silica ink-absorbing filler. The polymer film-forming resin can be a natural high molecular polymer such as starch, cellulose, guar gum and its modified products, or a polymer emulsion such as polyacrylic acid and polyurethane. For example, CN 116396650 A discloses an ink-absorbing coating, which includes the following preparation raw materials according to mass percentage: 5-15% composite resin emulsion, 1-2% silicate, 15-30% nano silicon dioxide, 0.4-0.6% dispersant, 0.1-0.3% defoamer and the balance of water, and the composite resin emulsion includes 10-20 parts of acrylate emulsion, 5-12 parts of waterborne polyurethane emulsion and 2-8 parts of compatibilizer. The ink-absorbing coating can simultaneously improve the basic performance and ink-absorbing performance of the coating. However, the patented technology uses a composite resin of acrylate and waterborne polyurethane to improve the basic performance of the coating, and needs to use a specific compatibilizer to improve compatibility, and needs to perform complex pretreatment on the nano silicon dioxide particles to improve its dispersion effect. The corresponding ingredient system and preparation method are relatively complex.

[0004] Therefore, it is a technical problem that those skilled in the art need to solve to provide an ink-absorbing coating having a simple component system, excellent coating performance, good adhesion to paper, excellent ink absorption performance, and excellent ink-absorbing particle dispersion performance. Summary of the invention

[0005] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing an ink-absorbing filler.

[0006] Another object of the present invention is to provide an ink-absorbing filler prepared by the above method.

[0007] Another object of the present invention is to provide a paper surface waterproof ink-absorbing coating emulsion containing the above-mentioned ink-absorbing filler.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing an ink-absorbing filler comprises the following steps:

[0010] (1) surface-modifying porous silica powder using an epoxy silane coupling agent to obtain epoxy-modified porous silica powder;

[0011] (2) Dissolving the cyclodextrin compound in an alkaline aqueous solution by heating, then adding the epoxy-modified porous silica powder of step (1) to react by stirring at the same temperature, filtering, washing and drying the product to obtain a cyclodextrin compound-modified porous silica ink-absorbing filler.

[0012] Furthermore, the D50 particle size of the porous silica powder in step (1) is in the range of 2 to 5 μm, which is a conventional raw material in the art.

[0013] Furthermore, the epoxysilane coupling agent in step (1) is 3-(2,3-epoxypropoxy)propyltrimethoxysilane or 3-(2,3-epoxypropoxy)propyltriethoxysilane; the amount of the epoxysilane coupling agent is 1 to 10% of the mass of the porous silica powder.

[0014] Furthermore, the surface modification method in step (1) is as follows: adding porous silica powder to an alcohol solvent containing 0.5 to 5% (v / v) water and stirring to disperse the mixture evenly, then dropping an epoxy silane coupling agent solution and stirring to react at a temperature of 30 to 60° C. for 1 to 6 hours, filtering and drying to obtain epoxy-modified porous silica powder.

[0015] Furthermore, the cyclodextrin compound in step (2) is cyclodextrin (including α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin), hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, and amino cyclodextrin.

[0016] Preferably, the added amount of the cyclodextrin compound is 2-10% of the mass of the epoxy-modified porous silica powder.

[0017] Furthermore, the alkaline aqueous solution in step (2) refers to a sodium hydroxide solution with a mass fraction of 0.5 to 5%.

[0018] Furthermore, the temperature of the heat-insulating stirring reaction in step (2) is 50 to 80°C.

[0019] Furthermore, before filtering in step (2), 0.5 to 2 times the total mass of ethanol of the reaction material is added to reduce the viscosity.

[0020] An ink-absorbing filler is prepared by the method.

[0021] A paper surface waterproof ink-absorbing coating emulsion containing the ink-absorbing filler comprises a main resin emulsion, a dispersant and the ink-absorbing filler.

[0022] Furthermore, the main resin emulsion is a compound of EVA emulsion, PVA aqueous solution and water-based polyurethane emulsion; and the dispersant is hexadecyltrimethylammonium chloride.

[0023] Furthermore, the mass percentage of the main resin emulsion is 88% to 95%, the mass percentage of the dispersant is 1% to 4%, and the mass percentage of the ink-absorbing filler is 4% to 8%.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention uses cyclodextrin compounds to modify the surface of conventional silica ink-absorbing fillers, which can significantly improve the stability of the ink-absorbing fillers in the main resin emulsion. At the same time, the chemical adsorption characteristics of the cyclodextrin compounds can further synergistically improve the ink absorption effect of the coating.

[0026] (2) The ink-absorbing filler of the present invention introduces a large number of polar groups through cyclodextrin compounds and the hydrogen bonding effect with the carboxyl, hydroxyl and amine units in the main resin emulsion binder can further improve the adhesion and water resistance of the coating on the paper; at the same time, the ink-absorbing filler has a stronger bonding force with the main resin, which can significantly improve the strength of the coating and paper.

[0027] (3) The preparation process of the ink-absorbing filler of the present invention does not use toxic or harmful organic solvents, and the preparation method is simple, which has the advantages of being green, environmentally friendly and low in cost. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0029] Example 1

[0030] A method for preparing an ink-absorbing filler comprises the following steps:

[0031] (1) Porous silica powder with a D50 particle size range of 2 to 5 μm is added to a 2% (v / v) ethanol solvent containing water and stirred to disperse evenly, and then a 4% 3-(2,3-epoxypropoxy)propyltrimethoxysilane solution of the porous silica powder is added dropwise, heated to 45° C. in a water bath and stirred for 2 h, and then filtered and dried to obtain epoxy-modified porous silica powder.

[0032] (2) β-cyclodextrin is heated and dissolved in a 2% by mass sodium hydroxide aqueous solution, and then the epoxy-modified porous silica powder of step (1) is added, wherein the amount of β-cyclodextrin added is 8% by mass of the epoxy-modified porous silica powder, and the mixture is stirred at 70° C. for 4 h. After the reaction is completed, ethanol in an amount of 1 times the total mass of the reaction material is added to reduce the viscosity, and the solid phase is filtered, washed, and dried to obtain a cyclodextrin compound-modified porous silica ink-absorbing filler.

[0033] Example 2

[0034] A method for preparing an ink-absorbing filler comprises the following steps:

[0035] (1) Porous silica powder with a D50 particle size range of 2 to 5 μm is added to a 1% (v / v) ethanol solvent containing water and stirred to disperse evenly, and then a 2% 3-(2,3-epoxypropoxy)propyltrimethoxysilane solution based on the mass of the porous silica powder is added dropwise, heated to 30° C. in a water bath and stirred for 6 hours, and then filtered and dried to obtain epoxy-modified porous silica powder.

[0036] (2) Hydroxyethyl-β-cyclodextrin (average molecular substitution degree of 7) is heated and dissolved in a 0.5% sodium hydroxide aqueous solution, and then the epoxy-modified porous silica powder of step (1) is added, and the amount of hydroxyethyl-β-cyclodextrin added is 2% of the mass of the epoxy-modified porous silica powder. The reaction is stirred at 50° C. for 6 hours. After the reaction is completed, 0.5 times the total mass of ethanol is added to reduce the viscosity. The solid phase is filtered, washed, and dried to obtain a cyclodextrin compound modified porous silica ink-absorbing filler.

[0037] Example 3

[0038] A method for preparing an ink-absorbing filler comprises the following steps:

[0039] (1) Porous silica powder with a D50 particle size range of 2 to 5 μm is added to a 3% (v / v) ethanol solvent containing water and stirred to disperse evenly, and then a 6% 3-(2,3-epoxypropoxy)propyltrimethoxysilane solution of the porous silica powder is added dropwise, heated to 40° C. in a water bath and stirred for 3 h, and then filtered and dried to obtain epoxy-modified porous silica powder.

[0040] (2) β-cyclodextrin is heated and dissolved in a 3% by mass sodium hydroxide aqueous solution, and then the epoxy-modified porous silica powder of step (1) is added, wherein the amount of β-cyclodextrin added is 10% of the mass of the epoxy-modified porous silica powder. The mixture is stirred and reacted at 60° C. for 5 h. After the reaction is completed, ethanol in an amount twice the total mass of the reaction material is added to reduce the viscosity. The solid phase is filtered, washed, and dried to obtain a cyclodextrin compound-modified porous silica ink-absorbing filler.

[0041] Comparative Example 1

[0042] This comparative example uses unmodified porous silica powder (D50 particle size range is 2 to 5 μm).

[0043] Example 4

[0044] A waterproof ink-absorbing coating emulsion for paper surface comprises a main resin emulsion, a dispersant and an ink-absorbing filler. The main resin emulsion is prepared by compounding an EVA emulsion with a solid content of 54.5%, a PVA aqueous solution with a solid content of 40% and an aqueous polyurethane emulsion with a solid content of 45% in a mass ratio of 1:1:1; the dispersant is hexadecyltrimethylammonium chloride. The mass percentage of the main resin emulsion is 92%, the mass percentage of the dispersant is 2%, and the mass percentage of the ink-absorbing filler is 6%.

[0045] The ink-absorbing fillers were respectively prepared from the samples of Examples 1 to 3 and Comparative Example 1, and the obtained ink-absorbing coating emulsions were applied to packaging printing paper (the original tensile strength was 3.8 kN / m, and the emulsion coating amount was 5 g / m 2 The surface of the (dry pulp) is dried and solidified to obtain a waterproof ink-absorbing coating.

[0046] The test results of the ink absorbency (ink absorption value tested according to GB 12911-91), stability (centrifuged at 3000 r / min for 10 min to observe whether precipitation or stratification occurs) of the obtained ink-absorbing coating emulsion, and the strength of paper coated with the waterproof ink-absorbing coating (according to GB / T 12914-2008) and water resistance (immersed in 48°C warm water for 48 h, dried at 80°C and tested for paper strength) are shown in Table 1 below.

[0047] Table 1

[0048] Test sample Ink absorption value stability Tensile Strength Water resistance Example 1 47％ No precipitation or separation 5.2kN / m 3.9kN / m Example 2 42％ No precipitation or separation 4.5kN / m 3.6kN / m Example 3 51％ No precipitation or separation 5.6kN / m 4.4kN / m Comparative Example 1 35％ Micro powder precipitation occurs 4.3kN / m 2.8kN / m

[0049] It can be seen from the results in Table 1 that the cyclodextrin compound modified porous silica ink-absorbing filler of the present invention can significantly improve the ink absorption performance and stability in the main resin emulsion compared with the conventional porous silica ink-absorbing filler. At the same time, it also has a significant improvement effect on the strength and water resistance of paper, especially the improvement effect on water resistance is very significant, the reason is that the introduction of the cyclodextrin compound is conducive to improving the binding force between the ink-absorbing filler and the main resin and paper at the same time, thereby achieving excellent structural strength improvement effect and water resistance effect.

[0050] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing an ink-absorbing filler, characterized in that: The method comprises the following preparation steps: (1) surface-modifying porous silica powder using an epoxy silane coupling agent to obtain epoxy-modified porous silica powder; (2) Dissolving the cyclodextrin compound in an alkaline aqueous solution by heating, then adding the epoxy-modified porous silica powder of step (1) to react by stirring at the same temperature, filtering, washing and drying the product to obtain a cyclodextrin compound-modified porous silica ink-absorbing filler.

2. The method for preparing an ink-absorbing filler according to claim 1, characterized in that: The D50 particle size range of the porous silica powder in step (1) is 2 to 5 μm; the epoxy silane coupling agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane or 3-(2,3-epoxypropoxy)propyltriethoxysilane; the amount of the epoxy silane coupling agent is 1 to 10% of the mass of the porous silica powder.

3. The method for preparing an ink-absorbing filler according to claim 1, characterized in that: The surface modification method in step (1) is as follows: adding porous silica powder to an alcohol solvent containing 0.5-5% water and stirring to disperse the mixture evenly, then dropping an epoxy silane coupling agent solution and stirring to react at 30-60° C. for 1-6 hours, filtering and drying to obtain epoxy-modified porous silica powder.

4. The method for preparing an ink-absorbing filler according to claim 1, characterized in that: The cyclodextrin compound in step (2) is cyclodextrin, hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, and amino cyclodextrin; the added amount of the cyclodextrin compound is 2-10% of the mass of the epoxy-modified porous silica powder.

5. The method for preparing an ink-absorbing filler according to claim 1, characterized in that: The alkaline aqueous solution in step (2) refers to a sodium hydroxide solution with a mass fraction of 0.5-5%; the temperature of the heat-insulating stirring reaction is 50-80°C.

6. The method for preparing an ink-absorbing filler according to claim 1, characterized in that: Before filtering in step (2), 0.5 to 2 times the total mass of ethanol is added to reduce the viscosity.

7. An ink-absorbing filler, characterized in that: It is prepared by the method according to any one of claims 1 to 6.

8. A waterproof ink-absorbing coating emulsion for paper surface, characterized in that: The invention comprises a main resin emulsion, a dispersant and the ink-absorbing filler as claimed in claim 7.

9. The paper surface waterproof ink-absorbing coating emulsion according to claim 8, characterized in that: The main resin emulsion is a compound of EVA emulsion, PVA aqueous solution and water-based polyurethane emulsion; the dispersant is hexadecyltrimethylammonium chloride.

10. The paper surface waterproof ink-absorbing coating emulsion according to claim 8, characterized in that: The mass percentage of the main resin emulsion is 88% to 95%, the mass percentage of the dispersant is 1% to 4%, and the mass percentage of the ink-absorbing filler is 4% to 8%.