Preparation process and application of modified polymer-based oil polish

Abstract

The invention discloses a preparation process and application of modified polymer-based oil polish, and the preparation process comprises the following steps: adding deionized water into a reactor, adding an emulsifier and modified silicon dioxide, adding part of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid, and uniformly stirring; adding an ammonium persulfate aqueous solution for reaction, dropwise adding the residual parts by mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid, heating for reaction after the dropwise addition of the monomer is completed, cooling to room temperature after the reaction is completed, and filtering to obtain a modified acrylate emulsion; uniformly mixing the modified acrylate emulsion, a flatting agent, a wetting agent, a coalescing agent, a defoaming agent and deionized water, and filtering to obtain the modified polymer-based oil polish. The oil polish disclosed by the invention has excellent leveling property, high glossiness and good wear resistance.

Description

Technical Field

[0001] This invention relates to the field of varnish technology, specifically to a preparation process and application of a modified polymer-based varnish. Background Technology

[0002] Varnish (also known as topcoat or polishing varnish) is a commonly used coating in the finishing process of printed materials, which combines decorative and protective functions. It is mainly used in post-printing finishing and packaging material treatment. Through a series of processes such as coating, leveling, drying, calendering and curing, the coating can form a uniform and transparent glossy film on the paper surface, which significantly improves the appearance of printed materials, making their colors more vibrant and their gloss more enhanced. At the same time, it gives them practical properties such as moisture resistance, stain resistance and fold resistance, thereby improving the overall decorative grade and practical value of printed materials.

[0003] Water-based varnishes are liquid coatings applied online on printing presses or offline on varnishing machines, using water as a carrier to increase the gloss, water resistance, and abrasion resistance of printed paper. There are many types of water-based film-forming resins, including rosin-modified maleic acid resins, water-soluble acrylic resins, styrene-modified maleic acid waxes, water-based amino resins, and polyvinyl alcohol. Acrylic resins dominate the water-based varnish market due to their superior performance. Their characteristics include: light color, long-lasting preservation of the original gloss and color of printed materials, resistance to decomposition or yellowing due to outdoor exposure or ultraviolet light, exhibiting excellent durability; outstanding heat resistance, not decomposing or discoloring at 170℃, and maintaining stability even at temperatures of 230℃ or higher; and excellent chemical resistance, effectively resisting contamination and erosion from acids, alkalis, salts, oils, and detergents. These characteristics collectively enhance the decorative effect and practical value of water-based varnishes.

[0004] Currently, while water-based acrylic varnishes have advantages in terms of environmental protection and safety, they still face significant challenges in practical applications: their leveling properties are poor, making it difficult to form a uniform and smooth surface after coating; their gloss is relatively low, making it difficult to meet the visual brightness requirements of high-end printed materials; and their abrasion resistance is insufficient, making them prone to scratches or wear during friction or daily use. These defects together limit the widespread application of this material in fine printing and high-requirement packaging fields. Summary of the Invention

[0005] This invention provides a preparation process and application of a modified polymer-based varnish, which solves the problems of insufficient abrasion resistance, poor leveling properties, and relatively low gloss of existing water-based varnishes.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows: This invention provides a process for preparing a modified polymer-based varnish, comprising the following steps: (1) Add deionized water to the reactor, along with emulsifier and modified silica, stir until homogeneous, and add one-third by weight of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid, and stir until homogeneous. (2) Heat to 45-55℃ and add ammonium persulfate aqueous solution. Heat to 80-85℃ and react for 0.5h. Add the remaining mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid dropwise over 1.5-2.5h. After the monomers are added, heat to 95℃ and react for 30-40min to complete the reaction. Cool to room temperature and adjust the pH to 7-8 with ammonia. Filter to obtain modified acrylate emulsion. (3) Mix the modified acrylic emulsion, leveling agent, wetting agent, film-forming aid, defoamer and deionized water evenly, filter, and obtain the modified polymer-based varnish.

[0007] The modified polymer-based varnish is made from the following components in parts by weight: 65-80 parts modified acrylic emulsion, 0.5-1.5 parts leveling agent, 0.1-2 parts wetting agent, 1-3 parts film-forming aid, 0.2-0.4 parts defoamer, and 15-30 parts deionized water.

[0008] The modified acrylate emulsion comprises the following raw materials in parts by weight: 20-25 parts methyl methacrylate, 30-40 parts ethyl acrylate, 10-15 parts butyl acrylate, 2-4 parts acrylic acid, 1-3 parts emulsifier, 5-15 parts modified silica, 15-36 parts ammonium persulfate aqueous solution, and 90-120 parts deionized water; the mass percentage concentration of the ammonium persulfate aqueous solution is 45-55%.

[0009] The modified silica is prepared by the following method: (1) Add KH-550 silane coupling agent to anhydrous ethanol, stir evenly, add nano silica powder, ultrasonically disperse for 45-60 min, then stir and react at 70-75℃ for 2-4 h, filter, wash and dry to obtain KH-550 modified nano silica. (2) Mix the KH-550 modified nano silica, glycidyl methacrylate and N,N-dimethylformamide prepared in step (1) evenly, add triethylamine catalyst under nitrogen protection, heat to 80-100℃ and react for 4-6 h. (3) After the reaction is completed, cool to room temperature, wash with ethanol to remove unreacted substances, and vacuum dry at 60-80℃ for 6-12h to obtain modified nano-silica.

[0010] In step (1), the mass ratio of KH-550 silane coupling agent to nano silica powder is 3:(8-12); the mass fraction of KH-550 silane coupling agent added to anhydrous ethanol is 0.2-0.4%.

[0011] In step (2), the mass ratio of KH-550 modified nano silica, glycidyl methacrylate and N,N-dimethylformamide is 1:(1-2):(5-10), and the mass ratio of triethylamine to KH-550 modified nano silica is (0.1-0.5):1.

[0012] This invention also provides the application of the modified polymer-based varnish prepared by the above-described process in paper-printed materials.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention prepares modified nano-silica through a two-step method: modification with KH-550 silane coupling agent + grafting with glycidyl methacrylate. This significantly improves the dispersibility and interfacial bonding of nano-silica in acrylate emulsions, effectively solving the problems of easy agglomeration and poor compatibility with polymers of nano-silica.

[0014] 2. In the preparation process of the modified nano-silica of the present invention, active groups are generated on the surface of silica through the grafting reaction of KH-550 and glycidyl methacrylate, which can form covalent bonds with polymers, greatly improving the interfacial bonding force. The grafted silica is more uniformly dispersed in the organic phase, reducing agglomeration.

[0015] 3. In the prior art, nano-silica is mostly introduced through physical blending or simple surface treatment, while the present invention achieves covalent bonding between nanoparticles and polymer chains through chemical grafting, thereby enhancing the stability and mechanical properties of the system.

[0016] 4. This invention achieves a balance of hardness, flexibility, and adhesion by compounding hard monomer methyl methacrylate, soft monomer ethyl acrylate / butyl acrylate, and functional monomer acrylic acid. The addition of modified silica further enhances the leveling performance and wear resistance of the coating, and improves the gloss of the coating compared with ordinary nano silica. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the following embodiments, the leveling agent comprises polyether-modified polydimethylsiloxane, the defoamer comprises polydimethylsilicone oil, the wetting agent is polyether-modified alkylsiloxane, and the film-forming aid is propylene glycol ethyl ether. Alkyl diphenyl ether sulfonate disodium salt (DSB), wherein the emulsifier is a mixture of alkyl diphenyl ether sulfonate disodium salt (DSB) and octylphenol polyoxyethylene ether (OP-10) in a mass ratio of 1:2. Example 1

[0019] This embodiment provides a modified silica, which is prepared by the following method: (1) Add 3 parts of KH-550 silane coupling agent to 1000 parts of anhydrous ethanol, stir evenly, add 10 parts of nano silica powder, ultrasonically disperse for 50 min, then stir and react at 70℃ for 3 h, filter, wash and dry to obtain KH-550 modified nano silica. (2) Mix 10 parts of KH-550 modified nano silica, 15 parts of glycidyl methacrylate and 80 parts of N,N-dimethylformamide prepared in step (1) evenly, add 3 parts of triethylamine catalyst under nitrogen protection, heat to 90℃ and react for 5h. (3) After the reaction is completed, cool to room temperature, wash with ethanol to remove unreacted substances, and dry under vacuum at 70°C for 8 hours to obtain nano-silica with double bond modification. Example 2

[0020] This embodiment provides a modified silica, which is prepared by the following method: (1) Add 4 parts of KH-550 silane coupling agent to 2000 parts of anhydrous ethanol, stir evenly, add 10.6 parts of nano silica powder, ultrasonically disperse for 60 min, then stir and react at 70℃ for 4 h, filter, wash and dry to obtain KH-550 modified nano silica. (2) Mix 10 parts of KH-550 modified nano silica, 10 parts of glycidyl methacrylate and 50 parts of N,N-dimethylformamide prepared in step (1) evenly, add 1 part of triethylamine catalyst under nitrogen protection, heat to 80℃ and react for 6h.

[0021] (3) After the reaction is completed, cool to room temperature, wash with ethanol to remove unreacted substances, and dry under vacuum at 60°C for 12 h to obtain nano-silica with double bond modification. Example 3

[0022] This embodiment provides a modified silica, which is prepared by the following method: (1) Add 4 parts of KH-550 silane coupling agent to 1000 parts of anhydrous ethanol, stir evenly, add 16 parts of nano silica powder, ultrasonically disperse for 45 min, then stir and react at 75℃ for 2 h, filter, wash and dry to obtain KH-550 modified nano silica. (3) Mix 10 parts of KH-550 modified nano silica, 20 parts of glycidyl methacrylate and 100 parts of N,N-dimethylformamide prepared in step (1) evenly, add triethylamine catalyst under nitrogen protection, heat to 100℃ and react for 4h. (4) After the reaction is completed, cool to room temperature, wash with ethanol to remove unreacted substances, and dry under vacuum at 80°C for 6 hours to obtain nano-silica with double bond modification. Example 4

[0023] This embodiment provides a preparation process for a modified polymer-based varnish, comprising the following steps: (1) Weigh out 22 parts of methyl methacrylate, 35 parts of ethyl acrylate, 12 parts of butyl acrylate and 3 parts of acrylic acid, and set aside; (2) Add 100 parts of deionized water to the reactor, along with 2 parts of emulsifier and 10 parts of modified silica prepared in Example 1. Stir until homogeneous, then add one-third by weight of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid, and stir until homogeneous. (3) Heat to 50°C and add 25 parts of ammonium persulfate aqueous solution (the mass percentage concentration of ammonium persulfate aqueous solution is 50%). Heat to 80°C and react for 0.5 h. Within 2 h, add the remaining mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid dropwise. After the monomers are added, heat to 95°C and react for 35 min to complete the reaction. Cool to room temperature, adjust the pH value to 7.5 with ammonia water, filter, and obtain modified acrylate emulsion. (4) Mix 70 parts of modified acrylic emulsion, 1 part of leveling agent, 1 part of wetting agent, 2 parts of film-forming aid, 0.3 parts of defoamer and 25 parts of deionized water evenly, filter, and obtain modified polymer-based varnish. Example 5

[0024] This embodiment provides a preparation process for a modified polymer-based varnish, comprising the following steps: (1) Weigh out 20 parts of methyl methacrylate, 40 parts of ethyl acrylate, 10 parts of butyl acrylate and 4 parts of acrylic acid, and set aside; (2) Add 90 parts of deionized water to the reactor, and add 1 part of emulsifier and 15 parts of modified silica prepared in Example 1. Stir evenly, and add one-third of the mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid. Stir evenly. (3) Heat to 45°C and add 36 parts of ammonium persulfate aqueous solution (the mass percentage concentration of ammonium persulfate aqueous solution is 45%). Heat to 85°C and react for 0.5 h. Within 1.5 h, add the remaining mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid dropwise. After the monomers are added, heat to 95°C and react for 40 min to complete the reaction. Cool to room temperature, adjust the pH value to 7 with ammonia water, filter, and obtain modified acrylate emulsion. (4) Mix 65 parts of modified acrylic emulsion, 1.5 parts of leveling agent, 0.1 parts of wetting agent, 3 parts of film-forming aid, 0.24 parts of defoamer and 30 parts of deionized water evenly, filter, and obtain modified polymer-based varnish. Example 6

[0025] This embodiment provides a preparation process for a modified polymer-based varnish, comprising the following steps: (1) Weigh out 25 parts of methyl methacrylate, 30 parts of ethyl acrylate, 15 parts of butyl acrylate and 2 parts of acrylic acid, and set aside; (2) Add 120 parts of deionized water to the reactor, and add 3 parts of emulsifier and 5 parts of modified silica prepared in Example 1. Stir evenly, and add one-third of the mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid. Stir evenly. (3) Heat to 55°C and add 15 parts of ammonium persulfate aqueous solution (the mass percentage concentration of ammonium persulfate aqueous solution is 52%). Heat to 80°C and react for 0.5 h. Add the remaining mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid dropwise over 2.5 h. After the monomers are added, heat to 95°C and react for 30 min to complete the reaction. Cool to room temperature, adjust the pH value to 8 with ammonia water, filter, and obtain modified acrylate emulsion. (4) Mix 80 parts of modified acrylic emulsion, 1.2 parts of leveling agent, 0.3 parts of wetting agent, 2.5 parts of film-forming aid, 0.25 parts of defoamer and 25 parts of deionized water evenly, filter, and obtain modified polymer-based varnish. Example 7

[0026] This embodiment provides a preparation process for a modified polymer-based varnish, comprising the following steps: (1) Weigh out 21 parts of methyl methacrylate, 38 parts of ethyl acrylate, 12 parts of butyl acrylate and 3 parts of acrylic acid for later use; (2) Add 105 parts of deionized water to the reactor, along with 3 parts of emulsifier and 8 parts of modified silica prepared in Example 1. Stir until homogeneous, then add one-third of the mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid, and stir until homogeneous. (3) Heat to 52℃ and add 20 parts of ammonium persulfate aqueous solution (the mass percentage concentration of ammonium persulfate aqueous solution is 55%). Heat to 80-85℃ and react for 0.5h. Add the remaining mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid dropwise within 2h. After the monomers are added, heat to 95℃ and react for 35min to complete the reaction. Cool to room temperature, adjust the pH value to 8 with ammonia water, filter, and obtain modified acrylate emulsion. (4) Mix 75 parts of modified acrylic emulsion, 0.5 parts of leveling agent, 2 parts of wetting agent, 1 part of film-forming aid, 0.4 parts of defoamer and 15 parts of deionized water evenly, filter, and obtain modified polymer-based varnish. Example 8

[0027] This embodiment provides a preparation process for a modified polymer-based varnish, comprising the following steps: (1) Weigh out 24 parts of methyl methacrylate, 32 parts of ethyl acrylate, 14 parts of butyl acrylate and 3 parts of acrylic acid, and set aside; (2) Add 95 parts of deionized water to the reactor, along with 3 parts of emulsifier and 12 parts of modified silica prepared in Example 1. Stir until homogeneous, then add one-third of the mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid, and stir until homogeneous. (3) Heat to 45℃ and add 32 parts of ammonium persulfate aqueous solution (the mass percentage concentration of ammonium persulfate aqueous solution is 48%). Heat to 80-85℃ and react for 0.5h. Add the remaining mass parts of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid dropwise within 2h. After the monomers are added, heat to 95℃ and react for 38min to complete the reaction. Cool to room temperature, adjust the pH value to 7 with ammonia water, filter, and obtain modified acrylate emulsion. (4) Mix 72 parts of modified acrylic emulsion, 0.8 parts of leveling agent, 0.4 parts of wetting agent, 2.5 parts of film-forming aid, 0.25 parts of defoamer and 25 parts of deionized water evenly, filter, and obtain modified polymer-based varnish. Comparative Example 1

[0028] This embodiment provides a preparation process for a modified polymer-based varnish. Compared with Example 4, no modified silica is added in this embodiment, but everything else is the same as in Example 4. Comparative Example 2

[0029] This embodiment provides a preparation process for a modified polymer-based varnish. Compared with Example 4, this embodiment only adds nano-silica, and everything else is the same as Example 4.

[0030] Samples were prepared using the varnishes obtained in Examples 4-8 and Comparative Examples 1-2. Their properties were tested and the results were recorded. Abrasion resistance test: The rubbing paper is used to rub the test sample under a load of 1.8 kg, at a speed of 43±2 reciprocating / min and a stroke of 25±5 mm. The number of rubbing times until the base color of the substrate is exposed is recorded. Gloss test: Apply varnish to white cardstock and after it is completely dry, measure the gloss using a WGG60 gloss meter. Leveling performance test: Refer to JB / T3998-1999 to test the leveling performance of the varnish.

[0031] The test results are shown in Table 1.

[0032]

[0033] As can be seen from the above data, compared with Examples 4-8, although the gloss of the product obtained in Comparative Example 1 was improved, the number of abrasion resistance cycles was significantly reduced, and the leveling performance decreased. This comparison shows that the introduction of modified nano-silica in this invention can effectively improve the abrasion resistance of the coating while maintaining a relatively stable coating gloss, thereby achieving synergistic optimization of leveling and abrasion resistance.

[0034] Compared with Examples 4-8, the gloss, abrasion resistance, and leveling properties of the product obtained in Comparative Example 2 were all reduced. It can be seen that, compared with ordinary nano silica, the present invention improves the dispersibility and compatibility of the modified silica by first modifying the nano silica with KH-550 silane coupling agent. The KH-550 modified silica forms covalent bonds with the epoxy resin intermediate, which significantly improves the dispersibility and compatibility of the modified silica, so that the coating film has better leveling properties, abrasion resistance, and gloss.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the preferred embodiments have been described in detail, those skilled in the art can still make appropriate modifications or equivalent substitutions to the solutions of the present invention, and such modifications or substitutions should be considered to still fall within the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation process for a modified polymer-based varnish, characterized in that... Includes the following steps: (1) Add deionized water to the reactor, along with emulsifier and modified silica, stir until homogeneous, and add one-third by weight of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid, and stir until homogeneous. (2) Heat to 45-55℃ and add ammonium persulfate aqueous solution. Heat to 80-85℃ and react for 0.5h. Add the remaining mass of methyl methacrylate, ethyl acrylate, butyl acrylate and acrylic acid dropwise over 1.5-2.5h. After the monomers are added, heat to 95℃ and react for 30-40min to complete the reaction. Cool to room temperature and adjust the pH to 7-8 with ammonia. Filter to obtain modified acrylate emulsion. (3) Mix the modified acrylic emulsion, leveling agent, wetting agent, film-forming aid, defoamer and deionized water evenly, filter, and obtain the modified polymer-based varnish.

2. The preparation process of a modified polymer-based varnish according to claim 1, characterized in that: The modified polymer-based varnish is made from the following components in parts by weight: 65-80 parts modified acrylic emulsion, 0.5-1.5 parts leveling agent, 0.1-2 parts wetting agent, 1-3 parts film-forming aid, 0.2-0.4 parts defoamer, and 15-30 parts deionized water.

3. The preparation process of a modified polymer-based varnish according to claim 1, characterized in that: The modified acrylate emulsion comprises the following raw materials in parts by weight: 20-25 parts methyl methacrylate, 30-40 parts ethyl acrylate, 10-15 parts butyl acrylate, 2-4 parts acrylic acid, 1-3 parts emulsifier, 5-15 parts modified silica, 15-36 parts ammonium persulfate aqueous solution, and 90-120 parts deionized water; the mass percentage concentration of the ammonium persulfate aqueous solution is 45-55%.

4. The preparation process of a modified polymer-based varnish according to claim 1, characterized in that: The modified silica is prepared by the following method: (1) Add KH-550 silane coupling agent to anhydrous ethanol, stir evenly, add nano silica powder, ultrasonically disperse for 45-60 min, then stir and react at 70-75℃ for 2-4 h, filter, wash and dry to obtain KH-550 modified nano silica. (2) Mix the KH-550 modified nano silica, glycidyl methacrylate and N,N-dimethylformamide prepared in step (1) evenly, add triethylamine catalyst under nitrogen protection, heat to 80-100℃ and react for 4-6 h. (3) After the reaction is completed, cool to room temperature, wash with ethanol to remove unreacted substances, and vacuum dry at 60-80℃ for 6-12h to obtain modified nano-silica.

5. The preparation process of a modified polymer-based varnish according to claim 4, characterized in that: In step (1), the mass ratio of KH-550 silane coupling agent to nano silica powder is 3:(8-12); the mass fraction of KH-550 silane coupling agent added to anhydrous ethanol is 0.2-0.4%.

6. The preparation process of a modified polymer-based varnish according to claim 4, characterized in that: In step (2), the mass ratio of KH-550 modified nano silica, glycidyl methacrylate and N,N-dimethylformamide is 1:(1-2):(5-10), and the mass ratio of triethylamine to KH-550 modified nano silica is (0.1-0.5):

1.

7. The use of the modified polymer-based varnish prepared by any one of the preparation processes of claims 1-6 in paper printed matter.

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