An ink-absorbing coating for the surface of PE film or PET aluminized film and its preparation method

Abstract

The present invention belongs to the technical field of printing coatings, and discloses an ink-absorbing coating for the surface of a PE film or a PET aluminized film and a preparation method thereof. The ink-absorbing coating comprises the following components by mass percentage: 60-80% of an acrylic resin emulsion binder, 8-20% of an ink-absorbing filler, 1-5% of a viscosity regulator, 1-4% of a dispersant, 0.1-0.3% of an antifoaming agent, and the balance being water; the ink-absorbing filler is porous silica modified by a cyclodextrin compound. The present invention uses porous silica modified by a cyclodextrin compound as the ink-absorbing filler. By utilizing the dual adsorption effects of the chemical adsorption of the cyclodextrin compound and the physical adsorption of the porous silica, the ink-absorbing performance of the ink-absorbing coating can be significantly improved, and the binding effect with the acrylic resin emulsion binder can be enhanced, and the dispersion effect and comprehensive performance of the ink-absorbing filler can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of printing coatings, and particularly relates to an ink-absorbing coating for the surface of a PE film or a PET aluminized film and a preparation method thereof. Background Art

[0002] With the growth of consumers' demand for personalized and small-batch packaging, the use of digital printing has become more and more widespread. Different from the need to customize complex printing plates for ordinary gravure printing, digital printing does not require plate making, but has higher requirements for the ink-absorbing properties of non-absorbent materials such as plastic films like PE films or PET aluminized films. Therefore, ink-absorbing coatings applied to the surface of plastic films have emerged.

[0003] The water-based ink-absorbing coating can quickly absorb ink or pigments, making the printed pattern clear and full, and the color reduction degree higher and more vivid. This characteristic enables the water-based ink-absorbing coating to perform excellently under the requirements of high-resolution printing, meeting the strict requirements of modern printed matter for color and clarity.

[0004] At present, due to the porous structure and good whiteness of SiO2, it has been widely recognized in the market as an ink-absorbent in the ink-absorbing coating. It not only has a fast adsorption speed and a large adsorption capacity for water-based ink, can improve the controllability of the dot diameter and the dot roundness, but also can reduce the scattering coefficient of the ink-absorbing layer and improve the density of the image. For example, CN 116396650 A discloses an ink-absorbing coating, and the ink-absorbing coating includes the following preparation raw materials by mass percentage: 5-15% of a composite resin emulsion, 1-2% of a silicate, 15-30% of nano-silica, 0.4-0.6% of a dispersant, 0.1-0.3% of an antifoaming agent, and the balance of water. The composite resin emulsion includes 10-20 parts of an acrylate emulsion, 5-12 parts of a water-based polyurethane emulsion, and 2-8 parts of a compatibilizer. This ink-absorbing coating can improve the basic performance and ink-absorbing performance of the coating at the same time. However, this patented technology uses a composite resin of acrylate and water-based polyurethane to improve the basic performance of the coating, requires a specific compatibilizer to improve compatibility, and requires complex pretreatment of nano-silica particles to improve their dispersion effect. The corresponding component system and preparation method are relatively complex.

[0005] Therefore, it is a technical problem to be solved by those skilled in the art to provide an ink-absorbing coating with a simple component system, excellent coating performance, good adhesion to plastic films such as PE films or PET aluminized films, excellent ink-absorbing performance, and excellent dispersion performance of ink-absorbing particles. Summary of the Invention

[0006] Aiming at the above-mentioned disadvantages and deficiencies existing in the prior art, the primary object of the present invention is to provide an ink-absorbing coating for the surface of a PE film or a PET aluminized film.

[0007] Another object of the present invention is to provide a method for preparing the ink-absorbing coating for the surface of the above-mentioned PE film or PET aluminized film.

[0008] The ink-absorbing coating of the present invention is mainly applied to the surfaces of PE and aluminized PET substrates. The surface of the film coated with this ink-absorbing coating can adapt to digital inkjet printing. The characters and patterns printed digitally have high clarity and good adhesion, and can also meet the requirements of subsequent processes such as lamination and bag making.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] An ink-absorbing coating for the surface of a PE film or PET aluminized film, comprising the following components by mass percentage:

[0011] 60-80% of acrylic resin emulsion binder, 8-20% of ink-absorbing filler, 1-5% of viscosity regulator, 1-4% of dispersant, 0.1-0.3% of defoamer, and the balance is water;

[0012] The ink-absorbing filler is cyclodextrin compound-modified porous silica, which is prepared by the following method:

[0013] The cyclodextrin compound is heated and dissolved in an anhydrous solvent, then an isocyanate group-containing silane coupling agent is added dropwise for heat preservation and stirring reaction. After the reaction is completed, porous silica fine powder is added and stirred and mixed evenly, water is added dropwise and the heat preservation and stirring reaction is continued. The product is filtered, washed and dried to obtain cyclodextrin compound-modified porous silica.

[0014] Further, the cyclodextrin compound is cyclodextrin (including α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin), hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, amino cyclodextrin; the dosage of the cyclodextrin compound is 2-10% of the mass of the porous silica fine powder.

[0015] Further, the anhydrous solvent is DMF (N,N-dimethylformamide), DMAC (N,N-dimethylacetamide).

[0016] Further, the isocyanate group-containing silane coupling agent is isocyanatopropyltrimethoxysilane, isocyanatopropyltriethoxysilane; the dosage of the isocyanate group-containing silane coupling agent is 1-5% of the mass of the porous silica fine powder.

[0017] Further, the porous silica fine powder is mesoporous (pore size between 2 nm and 50 nm) silica fine powder with a D50 particle size range of 2-μm. It is a conventional raw material in the art.

[0018] Further, the temperature for adding the isocyanate group-containing silane coupling agent dropwise for heat preservation and stirring reaction and adding water dropwise and continuing the heat preservation and stirring reaction is 50-80 °C, and the time is 2-6 h.

[0019] Further, the addition amount of water is 3 to 5 times the molar amount of the isocyanate group silane coupling agent. Adding a small amount of water can promote the hydrolysis of the coupling group to generate silanol, thereby promoting the surface modification reaction with the porous silica micropowder.

[0020] Further, the acrylic resin emulsion binder can be an aqueous acrylic resin emulsion prepared by copolymerizing conventional (meth)acrylate monomers and (meth)acrylic acid monomers. The acrylate monomers in the above aqueous acrylic resin emulsion provide good water resistance, and the acrylic acid monomers utilize their polarity and hydrogen bond effect to improve the adhesion to the plastic film and the binding effect with the cyclodextrin compound-modified porous silica ink-absorbing filler.

[0021] Preferably, the acrylic resin emulsion binder is prepared by the following method:

[0022] 1) Dissolve isocyanatoethyl (meth)acrylate in an anhydrous solvent, then add the cyclodextrin compound and dissolve or disperse it evenly. Heat to 50 - 80 °C and stir for reaction. After the reaction is completed, spray dry to obtain an acrylate-modified cyclodextrin compound crosslinking agent;

[0023] 2) Add (meth)acrylate monomers, (meth)acrylic acid monomers, the acrylate-modified cyclodextrin compound crosslinking agent, and an emulsifier to deionized water, stir and emulsify to obtain an emulsion; then heat to 60 - 90 °C and dropwise add an initiator solution for polymerization reaction to obtain the acrylic resin emulsion binder.

[0024] Further, in step 1), the cyclodextrin compound is cyclodextrin (including α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin), hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, amino cyclodextrin; the anhydrous solvent is DMF, DMAC.

[0025] Further, in step 1), the molar ratio of isocyanatoethyl (meth)acrylate to the cyclodextrin compound added is 2 - 6:1.

[0026] Further, in step 2), the (meth)acrylate monomers are methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; the mass ratio of the (meth)acrylate monomers, (meth)acrylic acid monomers, and the acrylate-modified cyclodextrin compound crosslinking agent added is 1:(0.2 - 0.8):(0.1 - 0.3).

[0027] Further, the emulsifier described in step 2) is sodium alkyl sulfonate, sodium alkyl benzene sulfonate, alkylphenol polyoxyethylene ether, or fatty alcohol polyoxyethylene ether; the addition amount of the emulsifier is 1% - 4% of the total mass of the (meth)acrylate monomer, (meth)acrylic acid monomer, and acrylate-modified cyclodextrin compound crosslinking agent.

[0028] Further, the initiator described in step 2) is ammonium persulfate, sodium persulfate, or potassium persulfate.

[0029] Further, the viscosity regulator is ethanol or isopropanol; the dispersant is polyvinyl alcohol; the defoaming agent is Degussa TEGO Foamex-825 defoaming agent.

[0030] The preparation method of the ink-absorbing coating on the surface of the above-mentioned PE film or PET aluminized film includes the following preparation steps:

[0031] Stir and mix the acrylic resin emulsion binder evenly with the viscosity regulator, dispersant, and water, then add the ink-absorbing filler and stir until evenly dispersed, and finally add the defoaming agent and mix well. After standing, the ink-absorbing coating on the surface of the PE film or PET aluminized film is obtained.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] (1) The present invention uses cyclodextrin compound-modified porous silica as the ink-absorbing filler. By utilizing the dual adsorption effects of the chemical adsorption of the cyclodextrin compound and the physical adsorption of the porous silica, the ink-absorbing performance of the ink-absorbing coating can be significantly improved. At the same time, modifying the porous silica with the cyclodextrin compound can improve its binding effect with the acrylic resin emulsion binder and enhance the dispersion effect of the ink-absorbing filler.

[0034] (2) The present invention further uses an acrylic resin emulsion crosslinked with a cyclodextrin compound as the binder, which can further improve the coating strength and water resistance. At the same time, the introduced cyclodextrin compound crosslinking unit can provide a large number of polar groups, which can significantly improve the adhesion to plastic films such as PE films or PET aluminized films. Finally, the acrylic resin emulsion binder crosslinked with the cyclodextrin compound can further improve the binding effect with the cyclodextrin compound-modified porous silica ink-absorbing filler, thereby improving the comprehensive performance of the coating. Specific Embodiments

[0035] The following further describes the present invention in detail with reference to examples, but the embodiments of the present invention are not limited thereto.

[0036] Example 1

[0037] A preparation method of an ink-absorbing coating on the surface of a PE film or PET aluminized film includes the following preparation steps:

[0038] (1) Preparation of Ink Absorbing Filler

[0039] Hydroxyethyl-β-cyclodextrin (with an average molecular substitution degree of 7) is heated and dissolved in anhydrous DMF solvent at 70 °C, and then isopropyltriethoxysilane coupling agent is added dropwise for heat preservation and stirring reaction for 3 h. After the reaction is completed, porous silica micropowder (mesoporous silica with a particle size range of 2 - 5 μm) is added and stirred and mixed evenly. The dosage of hydroxyethyl-β-cyclodextrin is 6% of the mass of the porous silica micropowder, and the dosage of isopropyltriethoxysilane is 3% of the mass of the porous silica micropowder. Then, deionized water with a molar amount 4 times that of isopropyltriethoxysilane is added dropwise and the heat preservation and stirring reaction continues for 2 h. The product is filtered, washed successively with deionized water and ethanol, and vacuum dried to obtain hydroxyethyl-β-cyclodextrin modified porous silica ink absorbing filler.

[0040] (2) Preparation of Acrylic Resin Emulsion Binder

[0041] Butyl acrylate, methyl methacrylate, acrylic acid and emulsifier sodium dodecylbenzenesulfonate are added to deionized water according to a mass ratio of 70:30:50:4, stirred and emulsified to obtain an emulsion; then the temperature is raised to 70 °C, and an ammonium persulfate initiator solution with a dosage of 0.2% of the total weight of the monomers is added dropwise for polymerization reaction for 4 h to obtain an acrylic resin emulsion binder with a solid content of 46%.

[0042] (3) Preparation of Ink Absorbing Coating

[0043] By weight percentage, 70% acrylic resin emulsion binder is stirred and mixed evenly with 2% isopropanol, 2% polyvinyl alcohol dispersant and 10.8% deionized water, then 15% ink absorbing filler is added and stirred and dispersed evenly, and finally 0.2% TEGO Foamex-825 defoamer is added and mixed evenly. After standing, an ink absorbing coating on the surface of PE film or PET aluminized film is obtained.

[0044] For the obtained ink absorbing coating in this example, the adhesion fastness (according to GB / T13217.7-2023), water resistance (soaked in warm water at 48 °C for 48 h, and the adhesion fastness is tested after drying at 80 °C), and ink absorbency (coated on the surface of PE film or PET aluminized film at 5 g / m 2(Dry pulp) After the ink-absorbing coating, the ink absorption value is tested according to GB 12911-91, and the stability is tested (centrifuged at 3000 r / min for 10 min to observe whether precipitation or stratification occurs). The test results show that the adhesion fastness on the printing substrates of PE film or PET aluminized film is 95%; the test results of water resistance show that the adhesion fastness on the printing substrate of PE film is 88%, and the adhesion fastness on the printing substrate of PET aluminized film is 85%; the test results of ink absorption show that the ink absorption value on the printing substrate of PE film is 39%, and the ink absorption value on the printing substrate of PET aluminized film is 40%; the test results of stability show that there is no precipitation or stratification.

[0045] Example 2

[0046] A preparation method of an ink-absorbing coating on the surface of a PE film or a PET aluminized film, comprising the following preparation steps:

[0047] (1) Preparation of ink-absorbing filler

[0048] β-cyclodextrin is heated and dissolved in an anhydrous DMF solvent at 70°C, and then isopropyltriethoxysilane coupling agent is added dropwise for heat-preserving stirring reaction for 3 h. After the reaction is completed, porous silica micropowder (mesoporous silica with a particle size range of 2-5 μm) is added and stirred and mixed evenly. The dosage of β-cyclodextrin is 2% of the mass of the porous silica micropowder, and the dosage of isopropyltriethoxysilane is 1% of the mass of the porous silica micropowder. Then, deionized water 6 times the molar amount of isopropyltriethoxysilane is added dropwise and the heat-preserving stirring reaction is continued for 2 h. The product is filtered, washed successively with deionized water and ethanol, and vacuum dried to obtain β-cyclodextrin-modified porous silica ink-absorbing filler.

[0049] (2) Preparation of acrylic resin emulsion binder

[0050] Butyl acrylate, ethyl methacrylate, methacrylic acid and emulsifier alkylphenol polyoxyethylene ether are added to deionized water according to a mass ratio of 60:40:80:5, stirred and emulsified to obtain an emulsion; then the temperature is raised to 70°C, and an ammonium persulfate initiator solution of 0.2% of the total weight of the monomers is added dropwise for polymerization reaction for 4 h to obtain an acrylic resin emulsion binder with a solid content of 45%.

[0051] (3) Preparation of ink-absorbing coating

[0052] By weight percentage, 80% acrylic resin emulsion binder is stirred and mixed evenly with 2% isopropanol, 2% polyvinyl alcohol dispersant and 7.8% deionized water, then 8% ink-absorbing filler is added and stirred and dispersed evenly, and finally 0.2% TEGO Foamex-825 defoaming agent is added and mixed evenly. After standing, an ink-absorbing coating on the surface of a PE film or a PET aluminized film is obtained.

[0053] The ink-absorbing coating obtained in this example was tested to have an adhesion fastness of 95% on the PE film printing substrate and 96% on the PET aluminized film printing substrate; the water resistance test results showed that the adhesion fastness was 84% on the PE film printing substrate and 83% on the PET aluminized film printing substrate; the ink absorption test results showed that the ink absorption values on both the PE film and the PET aluminized film printing substrates were 28%; the stability test results showed no precipitation or delamination.

[0054] Example 3

[0055] A preparation method of an ink-absorbing coating on the surface of a PE film or a PET aluminized film, comprising the following preparation steps:

[0056] (1) Preparation of ink-absorbing filler

[0057] Hydroxypropyl-β-cyclodextrin (average molecular substitution degree of 5.2) was heated and dissolved in anhydrous DMF solvent at 70°C, and then isocyanatopropyltrimethoxysilane coupling agent was added dropwise for heat-preserving stirring reaction for 3 h. After the reaction was completed, porous silica micropowder (mesoporous silica with a particle size range of 2 - 5 μm) was added and stirred and mixed evenly. The dosage of hydroxypropyl-β-cyclodextrin was 10% of the mass of the porous silica micropowder, and the dosage of isocyanatopropyltrimethoxysilane was 5% of the mass of the porous silica micropowder. Then, deionized water with a molar amount 3 times that of isocyanatopropyltrimethoxysilane was added dropwise and the heat-preserving stirring reaction was continued for 2 h. The product was filtered, washed successively with deionized water and ethanol, and vacuum dried to obtain hydroxypropyl-β-cyclodextrin modified porous silica ink-absorbing filler.

[0058] (2) Preparation of acrylic resin emulsion binder

[0059] Butyl acrylate, methyl methacrylate, acrylic acid and emulsifier sodium dodecylbenzenesulfonate were added to deionized water according to a mass ratio of 70:30:20:5, stirred and emulsified to obtain an emulsion; then the temperature was raised to 70°C, and an ammonium persulfate initiator solution accounting for 0.2% of the total weight of the monomers was added dropwise for polymerization reaction for 4 h to obtain an acrylic resin emulsion binder with a solid content of 48%.

[0060] (3) Preparation of ink-absorbing coating

[0061] By weight percentage, 60% acrylic resin emulsion binder was stirred and mixed evenly with 2% isopropyl alcohol, 2% polyvinyl alcohol dispersant and 15.8% deionized water, then 20% ink-absorbing filler was added and stirred and dispersed evenly, and finally 0.2% TEGO Foamex-825 defoamer was added and mixed evenly. After standing, an ink-absorbing coating on the surface of a PE film or a PET aluminized film was obtained.

[0062] The ink-absorbing coating obtained in this example was tested to have an adhesion fastness of 93% on the printing substrate of PE film and 94% on the printing substrate of PET aluminized film; the water resistance test results showed that the adhesion fastness on the printing substrate of PE film was 87% and that on the printing substrate of PET aluminized film was 88%; the ink absorption test results showed that the ink absorption value on the printing substrate of PE film was 46% and that on the printing substrate of PET aluminized film was 49%; the stability test results showed no precipitation or delamination.

[0063] Example 4

[0064] A preparation method of an ink-absorbing coating on the surface of a PE film or a PET aluminized film, comprising the following preparation steps:

[0065] (1) The preparation of the ink-absorbing filler is the same as that in Example 1.

[0066] (2) Preparation of the acrylic resin emulsion binder

[0067] 1) Dissolve isocyanatoethyl methacrylate in DMF solvent, then add hydroxyethyl-β-cyclodextrin (average molecular substitution degree is 7) and dissolve evenly. The molar ratio of isocyanatoethyl methacrylate to hydroxyethyl-β-cyclodextrin added is 2:1. Heat up to 70 °C and stir for 3 h. After the reaction is completed, spray dry to obtain an acrylate-modified cyclodextrin compound crosslinking agent.

[0068] 2) Add butyl acrylate, methyl methacrylate, acrylic acid, acrylate-modified cyclodextrin compound crosslinking agent and emulsifier sodium dodecylbenzenesulfonate to deionized water according to a mass ratio of 70:30:50:30:4, stir and emulsify to obtain an emulsion; then heat up to 70 °C and dropwise add an ammonium persulfate initiator solution of 0.2% of the total weight of the monomers for polymerization reaction for 4 h to obtain an acrylic resin emulsion binder with a solid content of 46%.

[0069] (3) The preparation of the ink-absorbing coating is the same as that in Example 1.

[0070] The ink-absorbing coating obtained in this example was tested to have an adhesion fastness of 100% on both the printing substrates of PE film and PET aluminized film; the water resistance test results showed that the adhesion fastness on the printing substrate of PE film was 95% and that on the printing substrate of PET aluminized film was 92%; the ink absorption test results showed that the ink absorption value on the printing substrate of PE film was 51% and that on the printing substrate of PET aluminized film was 52%; the stability test results showed no precipitation or delamination.

[0071] Example 5

[0072] A preparation method of an ink-absorbing coating on the surface of a PE film or a PET aluminized film, comprising the following preparation steps:

[0073] (1) The preparation of the ink-absorbing filler is the same as that in Example 1.

[0074] (2) Preparation of the acrylic resin emulsion binder

[0075] 1) Dissolve isocyanatoethyl acrylate in DMF solvent, then add β-cyclodextrin and dissolve and disperse evenly. The molar ratio of isocyanatoethyl methacrylate to β-cyclodextrin added is 4:1. Heat up to 70 °C and stir for 3 h. After the reaction is completed, spray dry to obtain an acrylate-modified cyclodextrin compound crosslinking agent.

[0076] 2) Add butyl acrylate, methyl methacrylate, acrylic acid, acrylate-modified cyclodextrin compound crosslinking agent and emulsifier sodium dodecylbenzenesulfonate to deionized water according to a mass ratio of 70:30:50:20:4, stir and emulsify to obtain an emulsion; then heat up to 70 °C and dropwise add an ammonium persulfate initiator solution of 0.2% of the total weight of the monomers for polymerization reaction for 4 h to obtain an acrylic resin emulsion binder with a solid content of 46%.

[0077] (3) The preparation of the ink-absorbing coating is the same as that in Example 1.

[0078] The ink-absorbing coating obtained in this example was tested and the adhesion fastness on both the PE film and the PET aluminized film printing substrates was 100%; the water resistance test results showed that the adhesion fastness on the PE film printing substrate was 96%, and the adhesion fastness on the PET aluminized film printing substrate was 94%; the ink absorption test results showed that the ink absorption values on both the PE film and the PET aluminized film printing substrates were 48%; the stability test results showed no precipitation or delamination.

[0079] Example 6

[0080] A preparation method of an ink-absorbing coating on the surface of a PE film or a PET aluminized film, comprising the following preparation steps:

[0081] (1) The preparation of the ink-absorbing filler is the same as that in Example 1.

[0082] (2) Preparation of the acrylic resin emulsion binder

[0083] 1) Dissolve isocyanatoethyl methacrylate in DMF solvent, then add hydroxypropyl-β-cyclodextrin (average molecular substitution degree is 5.2) and dissolve evenly. The molar ratio of isocyanatoethyl methacrylate to hydroxyethyl-β-cyclodextrin added is 6:1. Heat up to 70 °C and stir for 3 h. After the reaction is completed, spray dry to obtain an acrylate-modified cyclodextrin compound crosslinking agent.

[0084] (2) Butyl acrylate, methyl methacrylate, acrylic acid, acrylate-modified cyclodextrin compound crosslinking agent and emulsifier sodium dodecylbenzenesulfonate were added to deionized water according to a mass ratio of 70:30:50:10:4, stirred and emulsified to obtain an emulsion; then the temperature was raised to 70 °C, and an ammonium persulfate initiator solution accounting for 0.2% of the total weight of the monomers was added dropwise for a polymerization reaction for 4 h to obtain an acrylic resin emulsion binder with a solid content of 46%.

[0085] (3) The preparation of the ink-absorbing coating was the same as that in Example 1.

[0086] The ink-absorbing coating obtained in this example was tested and the adhesion fastness on both the PE film and the PET aluminized film printing substrates was 100%; the water resistance test results showed that the adhesion fastness on the PE film printing substrate was 94%, and the adhesion fastness on the PET aluminized film printing substrate was 93%; the ink absorption test results showed that the ink absorption value on the PE film printing substrate was 44%, and the ink absorption value on the PET aluminized film printing substrate was 45%; the stability test results showed no precipitation or stratification.

[0087] From the comparison results of the above Examples 4 to 6 and Example 1, it can be seen that by further introducing an acrylate-modified cyclodextrin compound crosslinking agent into the acrylic resin emulsion binder of the present invention, the adhesion fastness and water resistance of the obtained ink-absorbing coating on the PE film and the PET aluminized film printing substrates can be further significantly improved. And it also has an obvious effect on improving the ink absorption performance.

[0088] Comparative Example 1

[0089] A preparation method of an ink-absorbing coating on the surface of a PE film or a PET aluminized film, compared with Example 1, used an equal amount of unmodified porous silica micropowder (mesoporous silica with a particle size range of 2 - 5 μm) to replace the hydroxyethyl-β-cyclodextrin-modified porous silica ink-absorbing filler, and the rest was the same.

[0090] The ink-absorbing coating obtained in this comparative example was tested and the adhesion fastness on the PE film printing substrate was 91%, and the adhesion fastness on the PET aluminized film printing substrate was 90%; the water resistance test results showed that the adhesion fastness on the PE film printing substrate was 81%, and the adhesion fastness on the PET aluminized film printing substrate was 79%; the ink absorption test results showed that the ink absorption values on both the PE film and the PET aluminized film printing substrates were 33%; the stability test results showed obvious micropowder precipitation.

[0091] From the comparison results of Comparative Example 1 and Example 1, it can be seen that by using cyclodextrin compounds to modify the surface of silica ink-absorbing fillers, the stability of the ink-absorbing coating can be significantly improved. At the same time, due to the chemisorption characteristics of cyclodextrin compounds, the ink-absorbing effect of the coating can be further synergistically improved. Moreover, a large number of polar groups introduced by cyclodextrin compounds and the hydrogen bond effect with acrylic units in the acrylic resin emulsion binder can further improve the adhesion and water resistance of the coating on plastic films such as PE films or PET aluminized films.

[0092] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. An ink-absorbing coating on the surface of a PE film or a PET aluminized film, characterized in that, It comprises the following components by mass percentage: 60 - 80% of acrylic resin emulsion binder, 8 - 20% of ink-absorbing filler, 1 - 5% of viscosity regulator, 1 - 4% of dispersant, 0.1 - 0.3% of defoamer, and the balance is water; The ink-absorbing filler is cyclodextrin compound-modified porous silica, which is prepared by the following method: Dissolve the cyclodextrin compound in an anhydrous solvent by heating, then dropwise add an isocyanate group-containing silane coupling agent and carry out a heat-preserving stirring reaction. After the reaction is completed, add porous silica fine powder and stir to mix evenly. Dropwise add water and continue the heat-preserving stirring reaction. The product is filtered, washed, and dried to obtain cyclodextrin compound-modified porous silica; The cyclodextrin compound is cyclodextrin, hydroxyethyl cyclodextrin, hydroxypropyl cyclodextrin, carboxymethyl cyclodextrin, amino cyclodextrin; the dosage of the cyclodextrin compound is 2 - 10% of the mass of the porous silica fine powder; the anhydrous solvent is DMF, DMAC; The isocyanate group-containing silane coupling agent is isocyanatopropyltrimethoxysilane, isocyanatopropyltriethoxysilane; the dosage of the isocyanate group-containing silane coupling agent is 1 - 5% of the mass of the porous silica fine powder; the porous silica fine powder is mesoporous silica fine powder with a D50 particle size range of 2 - 5 μm; The temperature for dropping the isocyanate group-containing silane coupling agent and carrying out the heat-preserving stirring reaction and dropping water and continuing the heat-preserving stirring reaction is 50 - 80 °C, and the time is 2 - 6 h; the addition amount of water is 3 - 5 times the molar amount of the isocyanate group-containing silane coupling agent; The acrylic resin emulsion binder is prepared by the following method: 1) Dissolve isocyanatoethyl (meth)acrylate in an anhydrous solvent, then add the cyclodextrin compound and dissolve or disperse evenly. Heat to 50 - 80 °C and carry out a stirring reaction. After the reaction is completed, spray dry to obtain an acrylate-modified cyclodextrin compound crosslinking agent; 2) Add (meth)acrylate monomers, (meth)acrylic acid monomers, acrylate-modified cyclodextrin compound crosslinking agent, and emulsifier to deionized water, stir and emulsify to obtain an emulsion; then heat to 60 - 90 °C and dropwise add an initiator solution for polymerization reaction to obtain an acrylic resin emulsion binder; In step 1), the molar ratio of isocyanatoethyl (meth)acrylate to the cyclodextrin compound added is 2 - 6:1; In step 2), the mass ratio of (meth)acrylate monomers, (meth)acrylic acid monomers, and acrylate-modified cyclodextrin compound crosslinking agent added is 1:(0.2 - 0.8):(0.1 - 0.3).

2. The ink-absorbing coating for the surface of a PE film or a PET aluminized film according to claim 1, characterized in that, In step 2), the (meth)acrylate monomers are methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate.

3. A surface ink-absorbing coating for PE film or PET aluminized film according to claim 1, characterized in that In step 2), the emulsifier is sodium alkyl sulfonate, sodium alkyl benzene sulfonate, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether; the addition amount of the emulsifier is 1% - 4% of the total mass of (meth)acrylate monomers, (meth)acrylic acid monomers, and acrylate-modified cyclodextrin compound crosslinking agent; the initiator is ammonium persulfate, sodium persulfate, potassium persulfate.

4. A surface ink-absorbing coating for PE film or PET aluminized film according to claim 1, characterized in that, The viscosity regulator is ethanol or isopropanol; the dispersant is polyvinyl alcohol; the defoamer is Tego Foamex-825 defoamer.

5. A method for preparing an ink-absorbing coating on the surface of a PE film or a PET aluminized film according to any one of claims 1 to 4, characterized in that, It includes the following preparation steps: Stir and mix the acrylic resin emulsion binder, viscosity regulator, dispersant and water evenly, then add the ink-absorbing filler and stir to disperse evenly, and finally add the defoamer and mix evenly. After standing, the ink-absorbing coating on the surface of the PE film or PET aluminized film is obtained.