Preparation method and application of modified nano barium sulfate

Abstract

The invention belongs to the technical field of materials, and discloses a preparation method and application of modified nano barium sulfate. The preparation method comprises the following steps: firstly, preparing nano barium sulfate coated with silicon dioxide on the surface by utilizing nano barium sulfate and a sodium silicate aqueous solution; then utilizing a mixed solution of sulfuric acid and hydrogen peroxide to obtain hydroxylated silicon dioxide coated nano barium sulfate, adding isocyanate and a catalyst, and reacting to obtain silicon dioxide coated nano barium sulfate containing double bonds; the preparation method comprises the following steps: blending 1, 3-propane diamine and methyl acrylate, reacting, adding ethylenediamine and methyl acrylate, reacting, adding acrylic acid, and reacting to obtain a hyperbranched polymer containing double bonds; and blending the double-bond-containing silicon dioxide coated nano barium sulfate, the double-bond-containing hyperbranched polymer and methyl acrylate, adding an initiator, and reacting to obtain the modified nano barium sulfate. The nano barium sulfate is applied to the coating, so that a coating formed by the coating has good mechanical strength, wear resistance and impact resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and particularly relates to a preparation method and application of modified nano barium sulfate. Background Art

[0002] In the field of materials science, the development and application of nano-scale inorganic powders have become the key technical directions for improving material properties. With the surge in demand for high-performance composite materials in various industries, barium sulfate has gradually become a functional filler attracting much attention in fields such as coatings, plastics, and rubbers due to its excellent chemical stability, high refractive index, and low oil absorption. Barium sulfate has a long history of research and application as a bulk industrial product and many achievements. In the international market, the barium sulfate products of Sachtleben in Germany and Sakai Chemical in Japan have excellent performance and almost occupy the market share of high-end industries such as electronic inks, automotive coatings, and pigment additives. In China, there are no more than 15 production enterprises with a barium sulfate production capacity exceeding 10,000 tons, but the products have serious homogenization, low added value, relatively single structure, and strong versatility. China needs to import a large amount of high-quality precipitated barium sulfate, especially nano-precipitated barium sulfate. In addition, the domestic production technology of nano barium sulfate is lacking, and the nano barium sulfate produced mostly has problems such as easy agglomeration, poor dispersibility, and compatibility. Therefore, optimizing the production technology of nano barium sulfate and improving the quality of nano barium sulfate have become important research directions in the domestic nano barium sulfate field.

[0003] At the same time, the special surface properties of nano barium sulfate limit its dispersion and synergistic effect in matrix materials. Therefore, surface modification to enhance the interfacial affinity to break through the application bottleneck has become another important research direction for nano barium sulfate. Currently, physical coating and chemical modification are mostly used for the surface modification of nano barium sulfate. Physical coating usually uses inorganic substances, polymers, surfactants, etc. as coating agents to form an isolation layer on the surface of nano barium sulfate through adsorption or deposition; chemical modification uses silane coupling agents, titanate coupling agents, etc. to chemically react with the surface hydroxyl groups of nano barium sulfate to introduce organic functional groups to improve its surface polarity. These methods can change the surface energy of nano barium sulfate to a certain extent, but it is difficult to fundamentally solve the interfacial affinity problem with organic matrices.

[0004] The limitations of the existing technology are mainly reflected in: for physically coated nano barium sulfate, during high-speed stirring and dispersion or long-term storage, the interfacial layer is easily damaged, leading to particle agglomeration, resulting in sedimentation and stratification of coatings, and pitting and uneven gloss on the coating surface after spraying; although chemical modification improves the surface polarity, the crosslinking degree between the coupling agent and the resin base material is insufficient, and the interface is prone to cracking due to changes in environmental temperature and humidity after the paint film dries, and insufficient dispersion of nano particles will reduce the mechanical strength, wear resistance, impact resistance, etc. of the coating. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a preparation method of modified nano barium sulfate and its application. The nano barium sulfate prepared by the preparation method of the present invention has good dispersibility when applied to coatings, so that the coating formed by the coatings has good mechanical strength, wear resistance and impact resistance.

[0006] The first aspect of the present invention provides a preparation method of modified nano barium sulfate.

[0007] A preparation method of modified nano barium sulfate, comprising the following steps:

[0008] (1) Adding nano barium sulfate into an aqueous sodium silicate solution, adjusting the pH to alkaline, and performing the first heating reaction to obtain nano barium sulfate with a silica coating on the surface;

[0009] (2) Immersing the nano barium sulfate with a silica coating on the surface in a mixed solution of sulfuric acid and hydrogen peroxide, performing the second heating reaction to obtain nano barium sulfate coated with hydroxylated silica, and then adding isocyanate and a catalyst, and performing the third heating reaction to obtain nano barium sulfate coated with silica containing double bonds;

[0010] (3) Blending 1,3-propanediamine and methyl acrylate, heating and stirring for reaction, then adding ethylenediamine and methyl acrylate, continuing the reaction, and then adding acrylic acid, and continuing the reaction to obtain a hyperbranched polymer containing double bonds;

[0011] (4) Blending the nano barium sulfate coated with silica containing double bonds prepared in step (2), the hyperbranched polymer containing double bonds prepared in step (3) and methyl acrylate, adding an initiator, and heating for reaction to obtain the modified nano barium sulfate.

[0012] Preferably, in step (1), the pH is adjusted to 9.0 - 11.0, and more preferably to 9.5 - 10.5. At this pH, it is beneficial to the hydrolysis of the aqueous sodium silicate solution, thus facilitating the coating of silica on the surface of nano barium sulfate.

[0013] Preferably, in step (1), the temperature of the first heating reaction is 80 - 95 °C, and the heating reaction time is 2 - 3 hours.

[0014] Preferably, in step (1), the stirring speed during the first heating reaction is 200 - 500 revolutions per minute.

[0015] Preferably, in step (1), the concentration of the aqueous sodium silicate solution is 0.2 - 0.6 mol / L, and more preferably 0.3 - 0.5 mol / L.

[0016] Preferably, in step (1), the mass-volume ratio of the nano barium sulfate to the sodium silicate aqueous solution is 1 g:(1 - 3) mL, and more preferably 1 g:(1.2 - 2.5) mL.

[0017] Preferably, in step (2), the mass fraction of the sulfuric acid is 95 - 98%.

[0018] Preferably, in step (2), the mass fraction of the hydrogen peroxide is 10 - 30%.

[0019] Preferably, in step (2), the volume ratio of the sulfuric acid to the hydrogen peroxide is 3:(0.5 - 1.5), and more preferably 3:1.

[0020] Preferably, in step (2), the mass ratio of the nano barium sulfate coated with silica to the mixed solution of sulfuric acid and hydrogen peroxide is 1:(5 - 15), and more preferably 1:(10 - 15).

[0021] Preferably, in step (2), the mass ratio of the nano barium sulfate coated with silica, the isocyanate and the catalyst is 1:(0.1 - 0.5):(0.01 - 0.1), and more preferably 1:(0.1 - 0.4):(0.01 - 0.1).

[0022] Preferably, in step (2), the temperature of the second heating reaction is 65 - 80 °C and the time is 1 - 2 hours.

[0023] Preferably, in step (2), the catalyst includes an organotin catalyst, and more preferably dibutyltin dilaurate.

[0024] Preferably, in step (2), the temperature of the third heating reaction is 60 - 80 °C and the time is 2 - 4 hours.

[0025] Preferably, in step (3), the temperature of the heating and stirring reaction is 90 - 110 °C and the time is 1 - 3 hours.

[0026] Preferably, in step (3), ethylenediamine and methyl acrylate are added, and the time for continuous reaction is 1 - 3 hours, and then acrylic acid is added, and the time for continuous reaction is 1 - 3 hours. Step (3) involves multiple Michael addition and copolymerization reactions to construct a double bond-containing hyperbranched polymer.

[0027] Preferably, in step (3), the molar ratio of 1,3 - propanediamine, methyl acrylate, ethylenediamine, and acrylic acid is 1:(3 - 5):(0.5 - 1.5):(0.1 - 0.5), and more preferably 1:(4 - 4.6):(0.8 - 1.0):(0.1 - 0.2).

[0028] Preferably, in step (4), the mass ratio of the double bond-containing silica-coated barium sulfate, double bond-containing hyperbranched polymer, methyl acrylate, and initiator is 1: (1.5 - 2.5): (4 - 7): (0.1 - 0.5), and more preferably 1: (1.8 - 2.0): (6 - 6.5): (0.1 - 0.3).

[0029] Preferably, in step (4), the initiator is selected from azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO).

[0030] Preferably, in step (4), the temperature of the heating reaction is 70 - 90 °C, and the time is 1 - 4 hours.

[0031] The second aspect of the present invention provides an application of the preparation method of the modified barium sulfate nanoparticle.

[0032] The above preparation method is applied to the preparation of coatings.

[0033] A method for preparing a coating, comprising the following steps:

[0034] (1) Mix hydroxyacrylic resin, 2,2-dimethylolpropane-1,3-diol, pentaerythritol, modified barium sulfate nanoparticle, auxiliary agent, and solvent to obtain mixture A;

[0035] (2) Mix isocyanate and catalyst to obtain mixture B;

[0036] (3) Mix mixture A and mixture B to obtain the coating.

[0037] Preferably, the isocyanate is selected from at least one of toluene diisocyanate and diphenylmethane diisocyanate.

[0038] Preferably, the catalyst includes organotin. For example, dibutyltin dilaurate and bis(dodecylthio)dibutyltin.

[0039] Preferably, the auxiliary agent includes at least one of defoamer and sodium lauryl sulfate.

[0040] Preferably, the defoamer includes polydimethylsiloxane.

[0041] Preferably, the solvent includes water and / or ethanol. For example, the water can be deionized water.

[0042] Preferably, the mass ratio of the hydroxyacrylic resin, 2,2-dimethylolpropane-1,3-diol, pentaerythritol, and modified barium sulfate nanoparticle is 50: (3 - 15): (1 - 8): (15 - 35), and more preferably 50: (5 - 12): (3 - 8): (18 - 30).

[0043] Preferably, the mass ratio of the hydroxyl acrylic resin, the auxiliary agent, and the solvent is 50:(1 - 5):(10 - 60), and more preferably 1:(2 - 5):(10 - 50).

[0044] Preferably, the mass ratio of the isocyanate to the catalyst is 1:(0.1 - 0.8).

[0045] Preferably, the mass ratio of the mixture A to the mixture B is 10:(0.5 - 1.2), and more preferably 10:(0.6 - 1.1).

[0046] When the above-mentioned coating is used, the mixture A and the mixture B are mixed and then cured to obtain a coating film.

[0047] Preferably, the curing temperature is 40 - 100 °C, and the curing time is 60 - 140 minutes. More preferably, the curing temperature is 50 - 100 °C, and the curing time is 60 - 110 minutes.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] (1) First, the present invention coats nano-barium sulfate with nano-silica to form a core-shell structure. Through the physical barrier effect of the silica layer, the oxidation, crystal growth, corrosion, and agglomeration tendency of nano-barium sulfate are inhibited. At the same time, the surface properties are optimized and the density of active sites is significantly increased. Subsequently, hydroxylation treatment is used to further enrich the surface hydroxyl concentration and construct a highly active reaction interface. By using the reaction between isocyanate and hydroxyl, high-density unsaturated double bonds are introduced to endow the particles with polymerizable characteristics. Then, through the reaction with double-bond-containing hyperbranched polymers and acrylates, a polymer coating layer is constructed on the surface of the core-shell structure, and the interfacial compatibility between the modified nano-barium sulfate and the hydroxyl acrylic resin matrix is significantly improved through the synergistic effect of chemical bonding and physical entanglement. In addition, when applied to coating products, the three-dimensional cross-linked network formed by the hyperbranched polymer can significantly enhance the mechanical strength, wear resistance, and impact resistance in the coating system. At the same time, by controlling the addition amount of acrylic acid, an appropriate amount of amino groups are retained in the hyperbranched polymer, and the mechanical bearing capacity of the coating is further strengthened by using the dynamic cross-linking mechanism between amino groups and carboxyl / hydroxyl groups.

[0050] (2) During the preparation process of the coating of the present invention, by utilizing the interaction between the hydroxyl acrylic resin, 2,2-dimethylolpropane-1,3-diol, pentaerythritol, and the modified nano-barium sulfate, the coating film formed by the prepared coating has good mechanical strength (measured by tensile strength), wear resistance, and impact resistance. Description of the Drawings

[0051] Figure 1SEM (scanning electron microscope) image of the modified nano-barium sulfate prepared in Example 1. Detailed implementation manners

[0052] In order to make those skilled in the art more clearly understand the technical solutions described in the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection required by the present invention.

[0053] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial channels or can be obtained by existing known methods.

[0054] Example 1

[0055] A preparation method of modified nano-barium sulfate includes the following steps:

[0056] (1) Add nano-barium sulfate into an aqueous sodium silicate solution (concentration is 0.4 mol / L), the mass-volume ratio of nano-barium sulfate to the aqueous sodium silicate solution is 1 g: 2.5 mL, adjust the pH to 10 with sodium hydroxide solution, conduct the first heating reaction, the temperature of the heating reaction is 85 °C, the time of the heating reaction is 2.5 hours, and the stirring speed during the heating reaction is 250 revolutions per minute to obtain nano-barium sulfate with a silica coating on the surface;

[0057] (2) Immerse the nano-barium sulfate with a silica coating on the surface into a mixed solution of sulfuric acid and hydrogen peroxide (mass fraction of sulfuric acid is 98%, mass fraction of hydrogen peroxide is 30%, volume ratio of sulfuric acid to hydrogen peroxide is 3:1), conduct the second heating reaction, the temperature of the second heating reaction is 70 °C, the time is 1.5 hours to obtain nano-barium sulfate coated with hydroxylated silica, then add isocyanate (toluene diisocyanate) and catalyst (dibutyltin dilaurate), conduct the third heating reaction, the temperature of the third heating reaction is 70 °C, the time is 3 hours to obtain nano-barium sulfate coated with silica containing double bonds, wherein, the mass ratio of the nano-barium sulfate with a silica coating on the surface, isocyanate (toluene diisocyanate) and catalyst (dibutyltin dilaurate) is 1: 0.3: 0.01;

[0058] (3) Blend 1,3-propanediamine and methyl acrylate, conduct a heating and stirring reaction, the temperature of the heating and stirring reaction is 100 °C, the time is 1.5 hours, then add ethylenediamine and methyl acrylate, continue the reaction for 2 hours, then add acrylic acid, continue the reaction for 2 hours to obtain a hyperbranched polymer containing double bonds, wherein, the molar ratio of 1,3-propanediamine, methyl acrylate, ethylenediamine, and acrylic acid is 1: 4.6: 1: 0.2, methyl acrylate is added in 2 times, half each time;

[0059] (4) Blend the double bond-containing silica-coated barium sulfate prepared in step (2), the double bond-containing hyperbranched polymer prepared in step (3), and methyl acrylate, add an initiator (azobisisobutyronitrile), and carry out a heating reaction at a temperature of 80 °C for 3 hours to obtain modified barium sulfate nanoparticles. Among them, the mass ratio of the double bond-containing silica-coated barium sulfate, the double bond-containing hyperbranched polymer, methyl acrylate, and the initiator is 1:2:6:0.1.

[0060] Figure 1 It is the SEM (scanning electron microscope) image of the modified barium sulfate nanoparticles prepared in Example 1.

[0061] Example 2

[0062] A preparation method of modified barium sulfate nanoparticles, comprising the following steps:

[0063] (1) Add barium sulfate nanoparticles to an aqueous sodium silicate solution (concentration 0.5 mol / L), and the mass-volume ratio of barium sulfate nanoparticles to the aqueous sodium silicate solution is 1 g:3 mL. Adjust the pH to 10.5 with sodium hydroxide solution, and carry out the first heating reaction at a temperature of 80 °C for 2.5 hours. The stirring speed during the heating reaction is 250 revolutions per minute to obtain barium sulfate nanoparticles with a silica coating on the surface;

[0064] (2) Immerse the barium sulfate nanoparticles with a silica coating on the surface in a mixed solution of sulfuric acid and hydrogen peroxide (mass fraction of sulfuric acid is 98%, mass fraction of hydrogen peroxide is 30%, and the volume ratio of sulfuric acid to hydrogen peroxide is 3:1), and carry out the second heating reaction at a temperature of 75 °C for 1.5 hours to obtain hydroxylated silica-coated barium sulfate nanoparticles. Then add isocyanate (toluene diisocyanate) and a catalyst (dibutyltin dilaurate), and carry out the third heating reaction at a temperature of 75 °C for 3 hours to obtain double bond-containing silica-coated barium sulfate nanoparticles. Among them, the mass ratio of the barium sulfate nanoparticles with a silica coating on the surface, isocyanate (toluene diisocyanate), and catalyst (dibutyltin dilaurate) is 1:0.4:0.01;

[0065] (3) Blend 1,3-propanediamine and methyl acrylate, and carry out a heating and stirring reaction at a temperature of 95 °C for 1.5 hours. Then add ethylenediamine and methyl acrylate, and continue the reaction for 2.5 hours. Then add acrylic acid and continue the reaction for 2.5 hours to obtain a double bond-containing hyperbranched polymer. Among them, the molar ratio of 1,3-propanediamine, methyl acrylate, ethylenediamine, and acrylic acid is 1:4.6:1.1:0.3. Methyl acrylate is added in two portions, with half added each time;

[0066] (4) Blend the double-bond-containing silica-coated barium sulfate prepared in step (2), the double-bond-containing hyperbranched polymer prepared in step (3), and methyl acrylate, add an initiator (azobisisobutyronitrile), and carry out a heating reaction at a temperature of 85 °C for 3 hours to obtain modified barium sulfate nanoparticles. The mass ratio of the double-bond-containing silica-coated barium sulfate, the double-bond-containing hyperbranched polymer, methyl acrylate, and the initiator is 1:1.8:6.5:0.15.

[0067] Example 3

[0068] A method for preparing modified barium sulfate nanoparticles, comprising the following steps:

[0069] (1) Add barium sulfate nanoparticles to an aqueous sodium silicate solution (concentration: 0.3 mol / L) with a mass-to-volume ratio of barium sulfate nanoparticles to the aqueous sodium silicate solution of 1 g:2 mL. Adjust the pH to 10 with sodium hydroxide solution, and carry out the first heating reaction at a temperature of 85 °C for 2.5 hours with a stirring speed of 250 revolutions per minute during the heating reaction to obtain barium sulfate nanoparticles with a silica coating on the surface;

[0070] (2) Immerse the barium sulfate nanoparticles with a silica coating on the surface in a mixed solution of sulfuric acid and hydrogen peroxide (mass fraction of sulfuric acid: 98%, mass fraction of hydrogen peroxide: 30%, volume ratio of sulfuric acid to hydrogen peroxide: 3:1), and carry out the second heating reaction at a temperature of 80 °C for 1.5 hours to obtain hydroxylated silica-coated barium sulfate nanoparticles. Then add an isocyanate (toluene diisocyanate) and a catalyst (dibutyltin dilaurate), and carry out the third heating reaction at a temperature of 80 °C for 2.5 hours to obtain double-bond-containing silica-coated barium sulfate nanoparticles. The mass ratio of the barium sulfate nanoparticles with a silica coating on the surface, the isocyanate (toluene diisocyanate), and the catalyst (dibutyltin dilaurate) is 1:0.3:0.01;

[0071] (3) Blend 1,3-propanediamine and methyl acrylate, and carry out a heating and stirring reaction at a temperature of 100 °C for 2 hours. Then add ethylenediamine and methyl acrylate, and continue the reaction for 2 hours. Then add acrylic acid and continue the reaction for 2 hours to obtain a double-bond-containing hyperbranched polymer. The molar ratio of 1,3-propanediamine, methyl acrylate, ethylenediamine, and acrylic acid is 1:4.0:1:0.3. Methyl acrylate is added in 2 portions, with half added each time;

[0072] (4) Blend the silica-coated nano-barium sulfate containing double bonds prepared in step (2), the hyperbranched polymer containing double bonds prepared in step (3), and methyl acrylate, add an initiator (azobisisobutyronitrile), and carry out a heating reaction at a temperature of 80 °C for 3 hours to obtain modified nano-barium sulfate. Among them, the mass ratio of the silica-coated nano-barium sulfate containing double bonds, the hyperbranched polymer containing double bonds, methyl acrylate, and the initiator is 1:1.9:6.2:0.1.

[0073] Comparative Example 1

[0074] Compared with Example 1, the difference in Comparative Example 1 is only that the nano-barium sulfate with silica-coated surface prepared in step (2) is directly replaced by nano-barium sulfate, and other processes are the same as those in Example 1. That is, in the preparation process of the modified nano-barium sulfate in Comparative Example 1, the treatment in step (1) is not included.

[0075] Comparative Example 2

[0076] Compared with Example 1, the difference in Comparative Example 2 is only that the process in step (3) is different from that in Example 1, and other processes are the same as those in Example 1.

[0077] The content of step (3) in Comparative Example 2 is as follows:

[0078] Blend 1,3-propanediamine and methyl acrylate, carry out a heating and stirring reaction at a temperature of 100 °C for 2 hours, then add acrylic acid, and continue the reaction for 2 hours to obtain a hyperbranched polymer containing double bonds. Among them, the molar ratio of 1,3-propanediamine, methyl acrylate, and acrylic acid is 1:2.3:0.2.

[0079] Application Example 1

[0080] A method for preparing a coating, comprising the following steps:

[0081] (1) Mix hydroxyacrylic resin, 2,2-dimethylolpropane-1,3-diol, pentaerythritol, and then add the modified nano-barium sulfate prepared in Example 1, additives, and solvents, and the stirring speed during mixing is 800 revolutions per minute to obtain mixture A. Among them, the mass ratio of hydroxyacrylic resin, 2,2-dimethylolpropane-1,3-diol, pentaerythritol, the modified nano-barium sulfate prepared in Example 1, additives, and solvents is 50:8:5:25:2:50;

[0082] (2) Mix isocyanate (toluene diisocyanate) and catalyst (dibutyltin dilaurate), and the mass ratio of isocyanate to catalyst is 1:0.3 to obtain mixture B;

[0083] (3)Mixture A and mixture B are mixed with a mass ratio of mixture A to mixture B being 10:0.8 to obtain a coating material.

[0084] Application Example 2

[0085] Compared with Application Example 1, the difference in Application Example 2 is only that the modified nano barium sulfate prepared in Example 2 is used to replace the modified nano barium sulfate prepared in Example 1 in equal amounts, and other processes are the same as those in Application Example 1.

[0086] Application Example 3

[0087] Compared with Application Example 1, the difference in Application Example 3 is only that the modified nano barium sulfate prepared in Example 3 is used to replace the modified nano barium sulfate prepared in Example 1 in equal amounts, and other processes are the same as those in Application Example 1.

[0088] Comparative Application Example 1

[0089] Compared with Application Example 1, the difference in Comparative Application Example 1 is only that the modified nano barium sulfate prepared in Comparative Example 1 is used to replace the modified nano barium sulfate prepared in Example 1 in equal amounts, and other processes are the same as those in Application Example 1.

[0090] Comparative Application Example 2

[0091] Compared with Application Example 1, the difference in Comparative Application Example 2 is only that the modified nano barium sulfate prepared in Comparative Example 2 is used to replace the modified nano barium sulfate prepared in Example 1 in equal amounts, and other processes are the same as those in Application Example 1.

[0092] Comparative Application Example 3

[0093] Compared with Application Example 1, the difference in Comparative Application Example 3 is only that pentaerythritol is used to replace 2,2 - dimethylolpropane - 1,3 - diol in equal amounts, and other processes are the same as those in Application Example 1.

[0094] Product Effect Test

[0095] 1. Mechanical Strength Test

[0096] Take the coating materials prepared in the above Application Examples 1 - 3 and Comparative Application Examples 1 - 3, and refer to the standard GB / T19250 - 2013 to test the tensile strength corresponding to the coatings formed by the coating materials. The results are shown in Table 1.

[0097] Table 1

[0098] It can be seen from Table 1 that the tensile strength of the coatings formed by the coating materials corresponding to the application examples is significantly greater than that of the comparative application examples. Thus, it can be seen that in the preparation process of the modified nano barium sulfate of the present invention, the processes of step (2) and step (3) are very important and have a significant impact on the mechanical properties of the finally obtained coating, such as the tensile strength.

[0099] 2. Abrasion resistance and impact resistance test

[0100] Impact resistance: The test was carried out with reference to the standard "GB / T1732-93 Determination method for impact resistance of paint films".

[0101] Abrasion resistance: The test was carried out with reference to the standard "GB / T1768-89 Determination method for abrasion resistance of paint films", with a load of 500 g and a polishing rotation speed of 500 revolutions.

[0102] The test results of abrasion resistance and impact resistance are shown in Table 2.

[0103] Table 2

[0104] It can be seen from Table 2 that the abrasion resistance and impact resistance of the coating formed by the coating corresponding to the application example of the present invention are significantly greater than those of the application comparative example. It can also be seen from the results of Application Example 3 and Application Example 1 that pentaerythritol and 2,2-dimethylolpropane-1,3-diol need to be in the coating at the same time. After crosslinking and curing, a stable network structure can be formed, which also has a good stable dispersion effect on the modified nano-barium sulfate, thereby significantly improving the abrasion resistance and impact resistance of the coating formed by the coating.

Claims

1. A method for preparing modified nano-barium sulfate, characterized in that: The following steps are involved: (1) Adding nano-barium sulfate to a sodium silicate aqueous solution, adjusting the pH to alkaline, and performing a first heating reaction to obtain nano-barium sulfate with a surface coated with silicon dioxide; (2) immersing the nano-barium sulfate coated with silica in a mixed solution of sulfuric acid and hydrogen peroxide, performing a second heating reaction to obtain hydroxylated silica-coated nano-barium sulfate, and then adding isocyanate and a catalyst, performing a third heating reaction to obtain silica-coated nano-barium sulfate containing double bonds; (3) 1,3-propylenediamine and methyl acrylate are mixed, heated and stirred to react, and then ethylenediamine and methyl acrylate are added, and the reaction is continued, and then acrylic acid is added and the reaction is continued to obtain a hyperbranched polymer containing double bonds; (4) Blending the double-bond-containing silica-coated nano-barium sulfate prepared in step (2), the double-bond-containing hyperbranched polymer prepared in step (3), and methyl acrylate, adding an initiator, and heating the mixture to react, thereby obtaining the modified nano-barium sulfate.

2. The preparation method according to claim 1, wherein In step (1), the pH is adjusted to 9.0-11.0; and / or, in step (1), the temperature of the first heating reaction is 80-95° C., and the heating reaction time is 2-3 hours.

3. The preparation method according to claim 1, characterized in that In step (1), the concentration of the sodium silicate aqueous solution is 0.2-0.6 mol / L; and / or, in step (1), the mass volume ratio of the nano-barium sulfate to the sodium silicate aqueous solution is 1 g: (1-3) mL.

4. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the nano-barium sulfate with the surface coated with silicon dioxide to the mixed solution of sulfuric acid and hydrogen peroxide is 1: (5-15).

5. The preparation method according to claim 1, wherein In step (2), the temperature of the second heating reaction is 65-80°C and the time is 1-2 hours.

6. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the third heating reaction is 60-80°C and the time is 2-4 hours; and / or, in step (3), the temperature of the heating and stirring reaction is 90-110°C and the time is 1-3 hours.

7. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of 1,3-propylenediamine, methyl acrylate, ethylenediamine, and acrylic acid is 1: (3-5): (0.5-1.5): (0.1-0.5); and / or, in step (4), the mass ratio of the double-bond silica-coated nano-barium sulfate, double-bond hyperbranched polymer, methyl acrylate, and initiator is 1: (1.5-2.5): (4-7): (0.1-0.5).

8. Use of the preparation method according to any one of claims 1 to 7 in the preparation of coatings.

9. A method for preparing a coating, characterized in that: The following steps are involved: (1) mixing hydroxy acrylic resin, 2,2-dihydroxymethylpropane-1,3-diol, pentaerythritol, modified nano-barium sulfate prepared by the preparation method according to any one of claims 1 to 7, an additive, and a solvent to obtain a mixture A; (2) mixing isocyanate and catalyst to obtain mixture B; (3) The mixture A is mixed with the mixture B to obtain the coating.

10. The preparation method according to claim 9, characterized in that: The mass ratio of the hydroxy acrylic resin, 2,2-dihydroxymethylpropane-1,3-diol, pentaerythritol, and modified nano-barium sulfate is 50:(3-15):(1-8):(15-35); and / or the mass ratio of the mixture A to the mixture B is 10:(0.5-1.2).

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