A high-levelling aqueous varnish and its preparation process

Abstract

The present invention relates to the technical field of varnishes, and specifically to a high-leveling waterborne varnish and its preparation process. The high-leveling waterborne varnish comprises the following weight components: 10-25 parts of deionized water, 20-45 parts of modified acrylate emulsion, 0.1-0.5 part of defoamer, 0.1-3 parts of leveling agent, 0.1-2 parts of wetting agent, and 1-3 parts of film-forming auxiliary agent. In the present invention, deionized water and emulsifier are mixed evenly, then styrene, methyl methacrylate, butyl acrylate, acrylic acid, methacryloxymethylphenyl dimethylsilane and double-bond-containing nano calcium carbonate are added and mixed evenly. Then, under the action of an initiator, a polymerization reaction occurs to obtain a modified acrylate emulsion; the modified acrylate emulsion, deionized water, defoamer, leveling agent, wetting agent and film-forming auxiliary agent are mixed evenly and filtered to obtain a high-leveling waterborne varnish with high gloss and strong abrasion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of varnishes, and particularly to a high-leveling water-based varnish and a preparation process thereof. Background Art

[0002] With the improvement of people's living standards and the enhancement of environmental protection awareness, consumers have higher and higher requirements for product quality and environmental protection performance. Especially in the printing industry, environmental protection requirements have become the key factors restricting the development of traditional products. Most traditional varnishes are solvent-based, usually using polyurethane, SBS, EVA, etc. as the main resins, ethyl acetate, toluene, etc. as solvents, and supplemented with tackifying resins, plasticizers, etc. as additives. They have the disadvantages of flammability, volatility, and environmental pollution of organic solvents. Therefore, non-toxic and pollution-free water-based varnish products are favored by people and can replace the existing solvent-based varnish products that pollute the air.

[0003] Water-based varnish refers to a liquid that uses water as a carrier, is coated by an in-line printing press or an off-line varnishing machine, and is used to increase the gloss, water resistance, and abrasion resistance of paper printed products. Depending on the system, water-based varnishes can be divided into aqueous solution type and emulsion type. Among them, acrylate emulsion water-based varnishes have the characteristics of good film-forming performance, strong adhesion to the substrate, and not easy to turn yellow and change color under long-term strong sunlight irradiation, and have been widely studied and applied. However, acrylate water-based varnishes generally have problems such as poor leveling performance, low gloss, and insufficient abrasion resistance, and are greatly restricted in application.

[0004] Therefore, we propose a high-leveling water-based varnish and a preparation process thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-leveling water-based varnish and a preparation process thereof to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A preparation process of a high-leveling water-based varnish includes the following steps:

[0008] Step S1: Mix two-thirds of the mass portion of deionized water and an emulsifier evenly, and add styrene, methyl methacrylate, butyl acrylate, acrylic acid, methacryloxymethylphenyl dimethylsilane, and double-bond-containing nano calcium carbonate and mix evenly to obtain a pre-emulsion.

[0009] Step S2: Mix sodium bicarbonate and the remaining parts by mass of deionized water evenly, heat up to 80 - 85 °C, dropwise add one-third of the parts by mass of the pre-emulsion and one-third of the parts by mass of the ammonium persulfate aqueous solution, finish dropping in 1.5 - 2.0 h, keep warm for 30 - 40 min; heat up to 85 - 90 °C, dropwise add the remaining parts by mass of the pre-emulsion and the remaining parts by mass of the ammonium persulfate aqueous solution, finish dropping in 3 - 4 h, keep warm for 1 - 2 h, cool to room temperature, adjust the pH value to 8 - 9 with ammonia water, filter to obtain the modified acrylate emulsion;

[0010] Step S3: Mix the modified acrylate emulsion, deionized water, defoamer, leveling agent, wetting agent and film-forming aid evenly, filter to obtain the high-leveling water-based varnish.

[0011] Further, the high-leveling water-based varnish comprises the following weight components: 10 - 25 parts of deionized water, 20 - 45 parts of modified acrylate emulsion, 0.1 - 0.5 part of defoamer, 0.1 - 3 parts of leveling agent, 0.1 - 2 parts of wetting agent, 1 - 3 parts of film-forming aid.

[0012] Further, the modified acrylate emulsion comprises the following weight components: 0.5 - 1.0 part of sodium bicarbonate, 90 - 120 parts of deionized water, 1.0 - 3.0 parts of emulsifier, 10 - 15 parts of styrene, 20 - 25 parts of methyl methacrylate, 30 - 40 parts of butyl acrylate, 2 - 4 parts of acrylic acid, 3 - 5 parts of methacryloxymethylphenyl dimethylsilane, 5 - 15 parts of double-bond-containing nano calcium carbonate, 15 - 36 parts of ammonium persulfate aqueous solution.

[0013] Further, the concentration of the ammonium persulfate aqueous solution is 5 - 10 wt%.

[0014] Further, the preparation method of the double-bond-containing nano calcium carbonate is as follows:

[0015] Step (1): Add 2,3-epoxypropyltrimethylammonium chloride into deionized water and mix evenly, add nano calcium carbonate, disperse evenly by ultrasonic treatment, and perform ball milling treatment to obtain modified nano calcium carbonate;

[0016] Step (2): Under the protection of nitrogen, mix 1,3,5,7-tetramethylcyclotetrasiloxane, allyloxy polyoxyethylene ether and cashew phenol evenly, heat up to 90 - 100 °C, add chloroplatinic acid-isopropanol solution, react for 8 - 10 h, and perform vacuum distillation to obtain modified silicone;

[0017] Step (3): Mix the modified silicone, maleic anhydride and p-toluenesulfonic acid evenly, react at 60 - 80 °C for 3 - 5 h, and cool to room temperature to obtain an intermediate;

[0018] Step (4): Under nitrogen protection, uniformly mix the modified nano-calcium carbonate, the intermediate, and N,N-dimethylformamide, add tetraethylammonium bromide and hydroquinone and mix them evenly, heat up to 110 - 120 °C, react for 5 - 7 h, cool to room temperature, and after washing and drying, obtain nano-calcium carbonate containing double bonds.

[0019] Further, in the step (1), the mass ratio of nano-calcium carbonate, 2,3-epoxypropyltrimethylammonium chloride, and deionized water is 1:(1 - 3):(40 - 50).

[0020] Further, in the step (2), the mass ratio of 1,3,5,7-tetramethylcyclotetrasiloxane, allyloxypolyoxyethylene ether, and cardanol is 1:(2.0 - 2.5):(2 - 4).

[0021] Further, in the step (2), calculated by platinum atoms, the dosage of chloroplatinic acid-isopropanol solution is 0.0001 mol / L, and the mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid-isopropanol solution is 1:(50 - 100).

[0022] Further, in the step (3), the mass ratio of the modified silicone, maleic anhydride, and p-toluenesulfonic acid is 1:(1 - 2):(0.03 - 0.05).

[0023] Further, in the step (4), the mass ratio of the modified nano-calcium carbonate, the intermediate, and N,N-dimethylformamide is 1:(2 - 4):(20 - 30).

[0024] Further, the mass ratio of the modified nano-calcium carbonate, tetraethylammonium bromide, and hydroquinone is 1:(0.03 - 0.05):(0.01 - 0.03).

[0025] Further, the emulsifier is compounded from an anionic emulsifier and a non-ionic emulsifier with a mass ratio of 1:(1 - 4).

[0026] Further, the anionic emulsifier is one or more of sodium alkylbenzene sulfonate, ammonium alkyl alcohol polyether sulfate, sodium alkyl alcohol ether sulfate, alkyl (aryl) phosphate, and fatty alcohol (alkylphenol) polyoxyethylene ether phosphate.

[0027] Further, the non-ionic emulsifier is one or more of alkyl polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and alkylphenol ethoxylate.

[0028] Further, the film-forming aid is dipropylene glycol butyl ether.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. A high - leveling water - based varnish and its preparation process of the present invention modify nano - calcium carbonate with 2,3 - epoxypropyltrimethylammonium chloride. Through the adsorption of the positive charge of the quaternary ammonium salt on the surface of nano - calcium carbonate, the epoxy group at the other end is introduced onto the surface of nano - calcium carbonate to obtain modified nano - calcium carbonate, reducing the agglomeration phenomenon between calcium carbonate particles and improving its dispersibility in the organic matrix.

[0031] Through the hydrosilylation reaction of 1,3,5,7 - tetramethylcyclotetrasiloxane, allyloxy polyoxyethylene ether and cashew phenol, rigid cyclic siloxane, polyether segments and rigid benzene rings are introduced, which can effectively improve the leveling property and temperature resistance of the varnish and enhance its thermal stability. Through the carboxylation of the hydroxyl group in the modified silicone with maleic anhydride, an intermediate containing double bonds is produced. Finally, under the catalysis of tetraethylammonium bromide, the epoxy group on the surface of the modified nano - calcium carbonate reacts with the carboxyl group on the intermediate to undergo epoxy ring - opening reaction, obtaining nano - calcium carbonate containing double bonds. Using the nano - calcium carbonate containing double bonds as a polymerization monomer, a free - radical addition polymerization reaction is carried out with acrylate monomers, realizing the uniform dispersion of nano - calcium carbonate in the modified acrylate emulsion and significantly improving its wear resistance and leveling property.

[0032] 2. A high - leveling water - based varnish and its preparation process of the present invention are prepared by uniformly mixing a modified acrylate emulsion, deionized water, a defoaming agent, a leveling agent, a wetting agent and a film - forming auxiliary, and then filtering to obtain a high - leveling water - based varnish, which has high leveling property, glossiness and wear resistance. Specific Embodiments

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] In this embodiment, the defoaming agent: model is BYK - 022 from BYK of Germany; the leveling agent: model is BYK - 361N from BYK of Germany; the wetting agent: model is TEGO - 245 from Degussa of Germany; nano - calcium carbonate: particle size is 20nm, sourced from Shanghai Naiou Nano Technology Co., Ltd.; allyloxy polyoxyethylene ether: model is APEG - 300, sourced from Jiangsu Haian Petrochemical Factory.

[0035] In the following examples and comparative examples, 1 part is equal to 10g.

[0036] Example 1: A preparation process of a high - leveling water - based varnish, including the following steps:

[0037] Step S1: Mix 60 parts of deionized water and 1.0 part of emulsifier evenly, add 10 parts of styrene, 20 parts of methyl methacrylate, 30 parts of butyl acrylate, 2 parts of acrylic acid, 3 parts of methacryloxymethylphenyldimethylsilane and 5 parts of double bond-containing nano calcium carbonate and mix evenly to obtain a pre-emulsion; the emulsifier is composed of sodium alkyl benzene sulfonate and fatty alcohol polyoxyethylene ether compounded in a mass ratio of 1:1;

[0038] Step S2: Mix 0.5 part of sodium bicarbonate and 30 parts of deionized water evenly, heat up to 80 °C, dropwise add one-third of the mass of the pre-emulsion and 5 parts of 5wt% ammonium persulfate aqueous solution, finish dropping in 1.5 h, keep warm for 30 min; heat up to 85 °C, dropwise add the remaining mass of the pre-emulsion and 10 parts of 5wt% ammonium persulfate aqueous solution, finish dropping in 3 h, keep warm for 1 h, cool to room temperature, adjust the pH value to 8 with ammonia water, filter with a 300-mesh filter screen to obtain a modified acrylate emulsion;

[0039] Step S3: Mix 20 parts of the modified acrylate emulsion, 10 parts of deionized water, 0.1 part of defoamer, 0.1 part of leveling agent, 0.1 part of wetting agent and 1 part of film-forming aid evenly, filter with a 300-mesh filter screen to obtain a high-leveling water-based varnish;

[0040] The preparation method of the double bond-containing nano calcium carbonate is as follows:

[0041] Step (1): Add 5 parts of 2,3-epoxypropyltrimethylammonium chloride to 200 parts of deionized water and mix evenly, add 5 parts of nano calcium carbonate, disperse evenly by ultrasonic wave, and perform ball milling treatment to obtain modified nano calcium carbonate;

[0042] Step (2): Under nitrogen protection, mix 10 parts of 1,3,5,7-tetramethylcyclotetrasiloxane, 20 parts of allyloxy polyoxyethylene ether and 20 parts of cashew phenol evenly, heat up to 90 °C, add chloroplatinic acid-isopropanol solution, react for 8 h, and perform vacuum distillation to obtain modified silicone; based on platinum atoms, the dosage of the chloroplatinic acid-isopropanol solution is 0.0001 mol / L, and the mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid-isopropanol solution is 1:50;

[0043] Step (3): Mix 10 parts of the modified silicone, 10 parts of maleic anhydride and 0.3 part of p-toluenesulfonic acid evenly, react at 60 °C for 3 h, and cool to room temperature to obtain an intermediate;

[0044] Step (4): Under nitrogen protection, mix 5 parts of the modified nano calcium carbonate, 10 parts of the intermediate and 100 parts of N,N-dimethylformamide evenly, add 0.15 part of tetraethylammonium bromide and 0.05 part of hydroquinone and mix evenly, heat up to 110 °C, react for 5 h, cool to room temperature, and after washing and drying, obtain double bond-containing nano calcium carbonate.

[0045] Example 2: A preparation process of a high-levelling aqueous varnish, including the following processes:

[0046] Step S1: Mix 70 parts of deionized water and 2.0 parts of emulsifier evenly, add 12 parts of styrene, 22 parts of methyl methacrylate, 35 parts of butyl acrylate, 3 parts of acrylic acid, 4 parts of methacryloxymethylphenyl dimethylsilane and 10 parts of double-bond-containing nano calcium carbonate and mix evenly to obtain a pre-emulsion; The emulsifier is compounded from sodium alkylbenzene sulfonate and fatty alcohol polyoxyethylene ether with a mass ratio of 1:3.

[0047] Step S2: Mix 0.8 part of sodium bicarbonate and 35 parts of deionized water evenly, heat up to 80 °C, dropwise add one-third of the mass of the pre-emulsion and 9 parts of 8wt% ammonium persulfate aqueous solution, finish dropping in 1.5 h, keep warm for 30 min; Heat up to 85 °C, dropwise add the remaining mass of the pre-emulsion and 18 parts of 8wt% ammonium persulfate aqueous solution, finish dropping in 3 h, keep warm for 1 h, cool to room temperature, adjust the pH value to 8.5 with ammonia water, filter with a 300-mesh filter screen to obtain a modified acrylate emulsion.

[0048] Step S3: Mix 30 parts of modified acrylate emulsion, 18 parts of deionized water, 0.3 part of defoamer, 1 part of levelling agent, 1 part of wetting agent and 2 parts of film-forming aid evenly, filter with a 300-mesh filter screen to obtain a high-levelling aqueous varnish.

[0049] The preparation method of the double-bond-containing nano calcium carbonate is as follows:

[0050] Step (1): Add 20 parts of 2,3-epoxypropyltrimethylammonium chloride to 900 parts of deionized water and mix evenly, add 10 parts of nano calcium carbonate, disperse evenly by ultrasonic wave, and perform ball milling treatment to obtain modified nano calcium carbonate.

[0051] Step (2): Under nitrogen protection, mix 10 parts of 1,3,5,7-tetramethylcyclotetrasiloxane, 22 parts of allyloxy polyoxyethylene ether and 30 parts of cashew phenol evenly, heat up to 95 °C, add chloroplatinic acid-isopropanol solution, react for 9 h, and perform vacuum distillation to obtain modified organosilicon; Calculated by platinum atoms, the dosage of chloroplatinic acid-isopropanol solution is 0.0001 mol / L, and the mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid-isopropanol solution is 1:80.

[0052] Step (3): Mix 30 parts of modified organosilicon, 45 parts of maleic anhydride and 1.2 parts of p-toluenesulfonic acid evenly, react at 70 °C for 4 h, and cool to room temperature to obtain an intermediate.

[0053] Step (4): Under nitrogen protection, 10 parts of modified nano calcium carbonate, 30 parts of intermediate, and 250 parts of N,N-dimethylformamide were mixed evenly, 0.4 part of tetraethylammonium bromide and 0.2 part of hydroquinone were added and mixed evenly, the temperature was raised to 115 °C, and the reaction was carried out for 6 h. After cooling to room temperature, washing and drying were carried out to obtain nano calcium carbonate containing double bonds.

[0054] Example 3: A preparation process of a high leveling aqueous varnish, including the following processes:

[0055] Step S1: 80 parts of deionized water and 3.0 parts of emulsifier were mixed evenly, 15 parts of styrene, 25 parts of methyl methacrylate, 40 parts of butyl acrylate, 4 parts of acrylic acid, 5 parts of methacryloxymethylphenyl dimethylsilane, and 15 parts of nano calcium carbonate containing double bonds were added and mixed evenly to prepare a pre-emulsion; the emulsifier was composed of sodium alkylbenzene sulfonate and fatty alcohol polyoxyethylene ether compounded in a mass ratio of 1:4;

[0056] Step S2: 1.0 part of sodium bicarbonate and 40 parts of deionized water were mixed evenly, the temperature was raised to 80 °C, one-third of the mass of the pre-emulsion and 12 parts of 10 wt% ammonium persulfate aqueous solution were added dropwise, and the addition was completed in 1.5 h, and the temperature was kept for 30 min; the temperature was raised to 85 °C, the remaining mass of the pre-emulsion and 24 parts of 10 wt% ammonium persulfate aqueous solution were added dropwise, and the addition was completed in 3 h, and the temperature was kept for 1 h. After cooling to room temperature, the pH value was adjusted to 9 with ammonia water, and filtered through a 300-mesh sieve to obtain a modified acrylate emulsion;

[0057] Step S3: 45 parts of modified acrylate emulsion, 25 parts of deionized water, 0.5 part of defoamer, 3 parts of leveling agent, 2 parts of wetting agent, and 3 parts of film-forming aid were mixed evenly and filtered through a 300-mesh sieve to obtain a high leveling aqueous varnish;

[0058] The preparation method of nano calcium carbonate containing double bonds is as follows:

[0059] Step (1): 45 parts of 2,3-epoxypropyltrimethylammonium chloride were added to 2250 parts of deionized water and mixed evenly, 15 parts of nano calcium carbonate were added, and ultrasonic dispersion was carried out evenly, and after ball milling treatment, modified nano calcium carbonate was obtained;

[0060] Step (2): Under nitrogen protection, 10 parts of 1,3,5,7-tetramethylcyclotetrasiloxane, 25 parts of allyloxy polyoxyethylene ether, and 40 parts of cashew phenol were mixed evenly, the temperature was raised to 100 °C, a chloroplatinic acid-isopropanol solution was added, and the reaction was carried out for 10 h, and then vacuum distillation was carried out to obtain a modified silicone; based on platinum atoms, the dosage of the chloroplatinic acid-isopropanol solution was 0.0001 mol / L, and the mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid-isopropanol solution was 1:100;

[0061] Step (3): Mix 60 parts of modified silicone, 120 parts of maleic anhydride and 3 parts of p-toluenesulfonic acid evenly, react at 80 °C for 5 h, and cool to room temperature to obtain an intermediate;

[0062] Step (4): Under nitrogen protection, mix 15 parts of modified nano calcium carbonate, 60 parts of the intermediate and 450 parts of N,N-dimethylformamide evenly, add 0.75 parts of tetraethylammonium bromide and 0.45 parts of hydroquinone and mix evenly, heat up to 120 °C, react for 7 h, cool to room temperature, and after washing and drying, obtain double bond-containing nano calcium carbonate.

[0063] Comparative Example 1: The modified acrylate emulsion comprises the following weight components: 0.8 part of sodium bicarbonate, 105 parts of deionized water, 2 parts of emulsifier, 12 parts of styrene, 22 parts of methyl methacrylate, 35 parts of butyl acrylate, 3 parts of acrylic acid, 4 parts of methacryloxymethylphenyl dimethylsilane, 27 parts of ammonium persulfate aqueous solution; compared with Example 2, the modified acrylate emulsion in Comparative Example 2 does not add double bond-containing nano calcium carbonate, and other steps and processes are the same as those in Example 2.

[0064] Comparative Example 2: The modified acrylate latex comprises the following weight components: 0.8 part of sodium bicarbonate, 105 parts of deionized water, 2 parts of emulsifier, 12 parts of styrene, 22 parts of methyl methacrylate, 35 parts of butyl acrylate, 3 parts of acrylic acid, 4 parts of methacryloxymethylphenyl dimethylsilane, 10 parts of nano calcium carbonate, 27 parts of ammonium persulfate aqueous solution; compared with Example 2, Comparative Example 2 replaces the double bond-containing nano calcium carbonate with ordinary nano calcium carbonate of the same mass, and other steps and processes are the same as those in Example 2.

[0065] Comparative Example 3: A preparation process of a high leveling aqueous varnish comprises the following processes:

[0066] The preparation method of the double bond-containing nano calcium carbonate is as follows:

[0067] Step (1): Add 20 parts of 2,3-epoxypropyltrimethylammonium chloride to 900 parts of deionized water and mix evenly, add 10 parts of nano calcium carbonate, disperse evenly by ultrasonic treatment, and perform ball milling treatment to obtain modified nano calcium carbonate;

[0068] Step (2): Under nitrogen protection, mix 10 parts of 1,3,5,7-tetramethylcyclotetrasiloxane and 30 parts of cashew phenol evenly, heat up to 95 °C, add a chloroplatinic acid-isopropanol solution, react for 9 h, and perform vacuum distillation to obtain modified silicone; calculated by platinum atoms, the dosage of the chloroplatinic acid-isopropanol solution is 0.0001 mol / L, and the mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid-isopropanol solution is 1:80;

[0069] Step (3): Mix 30 parts of modified silicone, 45 parts of maleic anhydride, and 1.2 parts of p-toluenesulfonic acid evenly, react at 70 °C for 4 h, and cool to room temperature to obtain an intermediate;

[0070] Step (4): Under nitrogen protection, mix 10 parts of modified nano calcium carbonate, 5 parts of the intermediate, and 250 parts of N,N-dimethylformamide evenly, add 0.4 part of tetraethylammonium bromide and 0.2 part of hydroquinone and mix evenly, heat up to 115 °C, react for 6 h, cool to room temperature, and after washing and drying, obtain double bond-containing nano calcium carbonate;

[0071] Compared with Example 2, in Step (2) of Comparative Example 3, the mass ratio of 1,3,5,7-tetramethylcyclotetrasiloxane, allyloxy polyoxyethylene ether, and cashew phenol is 1:1:1, and other steps are the same as those in Example 2.

[0072] Experiment: Take the high leveling water-based varnishes obtained in Examples 1-3 and Comparative Examples 1-3, prepare specimens, and detect their properties respectively and record the detection results:

[0073] Glossiness test: Coat the water-based varnish on white cardboard, and after it is completely dried, measure the glossiness with a WGG60 glossiness meter; Abrasion resistance test: Coat the water-based varnish evenly on the surface of black cardboard, and after it is completely dried, according to the standard of GB / T 7706-2008, use a BGD630 ink rubbing resistance tester to measure and record the number of abrasion resistance times; Levelling property test: According to JB / T 3998-1999, test the levelling property of the varnish.

[0074] The test results are as follows:

[0075]

[0076] According to the data in the above table, the following conclusions can be clearly obtained:

[0077] 1. Compared with Examples 1-3, the glossiness of the product obtained in Comparative Example 1 has increased, but the number of abrasion resistance times and levelling property have decreased, indicating that adding double bond-containing nano calcium carbonate in the present invention can maintain the relative stability of glossiness while improving the abrasion resistance performance, thus taking into account the gloss and abrasion resistance of the coating film.

[0078] 2. Compared with Examples 1-3, the glossiness, number of abrasion resistance times, and levelling property of the product obtained in Comparative Example 2 have all decreased. It can be seen that compared with ordinary nano calcium carbonate, by introducing structures such as quaternary ammonium salts, polyether chain segments, and rigid benzene rings on the surface of nano calcium carbonate in the present invention, the dispersibility and compatibility of the modified nano calcium carbonate are significantly improved, making the coating film have better levelling property, abrasion resistance performance, and glossiness.

[0079] 3. Compared with Examples 1-3, the abrasion resistance times and leveling property of the product obtained in Comparative Example 3 both decreased. This indicates that when the addition amounts of allyloxy polyoxyethylene ether and cardanol are reduced in the present invention, the dispersibility and stability of the material will decline. It can be seen that the performance of the double-bond-containing nano calcium carbonate prepared by the present invention is affected by the ratio of each reagent in its preparation process. By selecting the mass ratio within the said range, the prepared double-bond-containing nano calcium carbonate has excellent dispersion performance, thereby improving the leveling property of the varnish.

[0080] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A preparation process of a high-leveling water-based varnish, characterized in that: The steps include: Step S1: Mix two-thirds of deionized water and an emulsifier in parts by weight, add styrene, methyl methacrylate, butyl acrylate, acrylic acid, methacryloyloxymethylphenyldimethylsilane and double-bond nano-calcium carbonate, and mix them evenly to prepare a pre-emulsion; Step S2: uniformly mix the sodium bicarbonate and the remaining mass parts of deionized water, raise the temperature to 80-85° C., drop one-third mass parts of the pre-emulsion and one-third mass parts of the ammonium persulfate aqueous solution, drip for 1.5-2.0 hours, and keep warm for 30-40 minutes; raise the temperature to 85-90° C., drop the remaining mass parts of the pre-emulsion and the remaining mass parts of the ammonium persulfate aqueous solution, drip for 3-4 hours, keep warm for 1-2 hours, cool to room temperature, adjust the pH value to 8-9 with ammonia water, filter, and obtain a modified acrylic emulsion; Step S3: uniformly mixing the modified acrylic emulsion, deionized water, defoamer, leveling agent, wetting agent and film-forming aid, and filtering to obtain a high-leveling water-based varnish; The preparation method of the double-bond nano calcium carbonate is as follows: Step (1): adding 2,3-epoxypropyltrimethylammonium chloride to deionized water and mixing evenly, adding nano calcium carbonate, ultrasonically dispersing evenly, and ball milling to obtain modified nano calcium carbonate; Step (2): Under nitrogen protection, 1,3,5,7-tetramethylcyclotetrasiloxane, allyloxy polyoxyethylene ether and cardanol are uniformly mixed, the temperature is raised to 90-100° C., chloroplatinic acid-isopropanol solution is added, the reaction is carried out for 8-10 hours, and vacuum distillation is performed to obtain modified silicone; Step (3): uniformly mix the modified organosilicon, maleic anhydride and p-toluenesulfonic acid, react at 60-80° C. for 3-5 hours, and cool to room temperature to obtain an intermediate; Step (4): Under nitrogen protection, the modified nano-calcium carbonate, the intermediate and N,N-dimethylformamide are mixed evenly, tetraethylammonium bromide and hydroquinone are added and mixed evenly, the temperature is raised to 110-120°C, the reaction is performed for 5-7 hours, the mixture is cooled to room temperature, and after washing and drying, nano-calcium carbonate containing double bonds is obtained.

2. The preparation process of a high-leveling water-based varnish according to claim 1, characterized in that: The high-leveling water-based varnish comprises the following components by weight: 10-25 parts of deionized water, 20-45 parts of modified acrylic ester emulsion, 0.1-0.5 parts of defoaming agent, 0.1-3 parts of leveling agent, 0.1-2 parts of wetting agent and 1-3 parts of film-forming aid.

3. The preparation process of a high-leveling water-based varnish according to claim 2, characterized in that: The modified acrylic emulsion comprises the following components by weight: 0.5-1.0 parts of sodium bicarbonate, 90-120 parts of deionized water, 1.0-3.0 parts of emulsifier, 10-15 parts of styrene, 20-25 parts of methyl methacrylate, 30-40 parts of butyl acrylate, 2-4 parts of acrylic acid, 3-5 parts of methacryloyloxymethylphenyldimethylsilane, 5-15 parts of double-bond nano calcium carbonate, and 15-36 parts of ammonium persulfate aqueous solution.

4. The preparation process of a high-leveling water-based varnish according to claim 1, characterized in that: In the step (1), the mass ratio of nano calcium carbonate, 2,3-epoxypropyltrimethylammonium chloride and deionized water is 1:(1-3):(40-50).

5. The process for preparing a high-leveling water-based varnish according to claim 1, characterized in that: In the step (2), the mass ratio of 1,3,5,7-tetramethylcyclotetrasiloxane, allyloxy polyoxyethylene ether and cardanol is 1:(2.0-2.5):(2-4).

6. The process for preparing a high-leveling water-based varnish according to claim 1, characterized in that: In the step (4), the mass ratio of modified nano-calcium carbonate, intermediate, tetraethylammonium bromide and hydroquinone is 1:(2-4):(0.03-0.05):(0.01-0.03).

7. The process for preparing a high-leveling water-based varnish according to claim 3, characterized in that: The concentration of the ammonium persulfate aqueous solution is 5-10 wt %.

8. The process for preparing a high-leveling water-based varnish according to claim 3, characterized in that: The emulsifier is prepared by compounding an anionic emulsifier and a nonionic emulsifier in a mass ratio of 1:(1-4).

9. A high-leveling water-based varnish prepared according to the preparation process according to any one of claims 1 to 8.

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