Preparation method of acrylate copolymer for dispersing water-based organic and inorganic pigments

Abstract

The invention discloses a preparation method of an acrylate copolymer for dispersing water-based organic and inorganic pigments, and relates to the technical field of preparation of acrylate dispersants.The preparation process is simple, products are easy to obtain, the monomer conversion rate can be increased by changing the adding form of an initiator and grading generated copolymerization reactants in real time, and the product yield is increased. The preparation efficiency of the acrylate copolymer is further improved, and meanwhile, the acrylate copolymer obtained by the preparation method has the characteristics of more uniform molecular structure and more stable performance, and has excellent dispersion stability on water-based organic and inorganic pigments; when being applied to the water-based building coating, the dispersing agent has a relatively good dispersing effect and a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of preparing acrylic ester dispersants, and in particular relates to a method for preparing an acrylic ester copolymer for dispersing water-based organic and inorganic pigments. Background Art

[0002] With the need for new developments in architectural coatings technology, the requirements for the refinement of various functional additives used in coatings are becoming increasingly higher. In architectural coatings production technology, pigment dispersion is an important part of coating manufacturing technology. Pigment dispersion refers to the process in which the secondary aggregates of the pigment are wetting and dispersed under the action of mechanical force to obtain a stable pigment dispersion suspension, which includes three inseparable processes: wetting, dispersion and stabilization. Wetting is a process of pigment surface displacement, the main purpose of which is to reduce the interfacial tension of the substance. Dispersion is the process in which the aggregates of the pigment are separated under the action of external forces; stabilization is the process in which the pigment no longer flocculates after dispersion. The addition of dispersants can promote better wetting of water on the pigment surface, produce different affinity anchoring binding modes with the pigment surface, and form stability among the pigment-dispersant-system. The main mode of action of pigment dispersion stabilization is through steric hindrance and charge effects, which are the determining factors for whether the pigment is stable in the water-based architectural coating system.

[0003] Dispersants used in water-based coatings are generally divided into three categories: inorganic salts, surfactants, and polymer compounds. In modern architectural coating formulations, inorganic salts and surfactant dispersants are not used as the main dispersants in water-based architectural coatings. Polymeric acrylic compounds are currently the most commonly used dispersants in architectural coatings. Among them, acrylate copolymers are a widely used class of polymer dispersants. Therefore, optimizing and improving the molecular structure and dispersibility of acrylate copolymers is of positive significance to promoting their use in water-based architectural coatings. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a method for preparing an acrylic copolymer for aqueous organic and inorganic pigment dispersion.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] As a first aspect of the present invention, the present invention provides a method for preparing an acrylic copolymer for aqueous organic and inorganic pigment dispersion, wherein the acrylic copolymer is prepared from the following components in parts by weight: 60-90 parts of a polymerizable monomer, 0.5-2 parts of an initiator, 0.5-1.5 parts of a catalyst, and 20-40 parts of an organic solvent, wherein the polymerizable monomer comprises methacrylic acid, cyclobenzyl acrylate, and tert-butylaminoethyl acrylate;

[0007] The method for preparing the acrylic acid ester copolymer comprises the following steps:

[0008] Step 1: dissolving the polymerization monomer and the initiator accounting for 40-50 wt % of the total amount of the initiator in an organic solvent accounting for 40-50 wt % of the total amount of the organic solvent to obtain a first solution;

[0009] Step 2: dissolving 30-40 wt % of the initiator in an organic solvent ...

[0010] Step 3: firstly, the first solution obtained in step 1 is heated to 60-80° C. in the presence of a catalyst, and then the second solution obtained in step 2 is uniformly added to the first solution in the form of atomization within 2-3 hours, and the temperature is kept for 4-6 hours after the addition is completed. While the temperature is kept, the obtained products are graded in real time to obtain a primary product and a secondary product, and the remaining initiator and organic solvent are added to the secondary product, and the temperature is raised to 80-100° C., and the temperature is continued to be kept, and after the temperature is kept, the primary product and the secondary product are mixed to obtain a polymerization reaction product;

[0011] Step 4: Centrifuge the polymerization product obtained in step 3 to obtain the acrylic acid ester copolymer.

[0012] As a further optimization scheme of the present invention, the organic solvent is one or two of ester and ketone solvents mixed in any ratio, the catalyst is a supported solid acid catalyst, and the initiator is ammonium persulfate, potassium persulfate or sodium persulfate.

[0013] As a further optimization scheme of the present invention, in the weight parts of the polymerizable monomers, the methacrylic acid is 40-50 parts, the cyclobenzyl acrylate is 10-25 parts and the tert-butylaminoethyl acrylate is 10-15 parts.

[0014] As a second aspect of the present invention, the present invention further provides an acrylic copolymer for aqueous organic and inorganic pigment dispersion prepared by any of the preparation methods described above.

[0015] As a third aspect of the present invention, the present invention also provides a preparation device for an acrylic copolymer for aqueous organic and inorganic pigment dispersion as described above, comprising a dissolving kettle 1 for preparing a first solution, a dissolving kettle 2 for preparing a second solution, and a storage tank for storing the acrylic copolymer, and further comprising:

[0016] A polymerization reactor connected to a dissolving kettle outlet via a pipeline connected in series with a metering pumping unit 2, wherein a fixed bed with a catalyst fixed therein and a classification unit for classifying copolymerization products in real time to obtain a primary product and a secondary product are arranged inside the polymerization reactor, wherein the classification unit has a primary reaction chamber and a secondary reaction chamber, and the secondary reaction chamber is connected to a supplementary pipeline;

[0017] An atomizing unit connected to the second liquid outlet of the dissolving kettle through a pipeline, wherein one end of the atomizing unit extending into the polymerization reactor is connected to a dispersion structure arranged outside the classification unit;

[0018] A metering pumping unit 1 connected to the dissolving kettle 1, the dissolving kettle 2 and the supplementary pipeline respectively through pipelines, for quantitatively conveying the initiator and the organic solvent to the dissolving kettle 1, the dissolving kettle 2 and the supplementary pipeline;

[0019] And a centrifugal separation unit connected to the discharge ports of the polymerization reactor through pipelines, used for centrifugal separation of the polymerization reaction product, wherein the discharge port of the centrifugal separation unit is connected to the storage tank through the pipeline.

[0020] As a further optimization scheme of the present invention, the polymerization reactor includes a reactor body and a driving rotating unit for driving the classifying unit to rotate. The interior of the reactor body is provided with a partition to form two compartments interconnected at the top ends, and the fixed bed and the classifying unit are respectively arranged in the two compartments.

[0021] As a further optimization scheme of the present invention, the classification unit includes a shell, a liquid outlet member arranged in the middle of the shell, a swirl rod member arranged in the upper half of the shell, and a tubular separator arranged in the lower half of the shell, the lower end of the liquid outlet member is connected to the lower half of the shell, and a separation membrane is arranged outside the tubular separator;

[0022] The top of the tubular separator is provided with a connecting pipe connected to the upper half of the shell, the inner wall of the connecting pipe is provided with a built-in swirl blade connected to the swirl rod, and the outer wall of the connecting pipe is provided with an external swirl blade at a position inside the liquid outlet.

[0023] As a further optimization scheme of the present invention, the preparation device also includes a heat transfer oil circulation heating unit, and the two compartments are respectively provided with circulation coil 1 and circulation coil 2, and the two ends of the circulation coil 1 and circulation coil 2 are respectively connected to the inlet and outlet liquid ends of the heat transfer oil circulation heating unit.

[0024] As a further optimization scheme of the present invention, the dispersion structure includes a swirl plate and a guide cover that are relatively arranged, the swirl plate is arranged opposite to the lower end opening of the guide cover, and the feed port of the guide cover is connected to the discharge port of the atomization unit through a pipeline.

[0025] As a second aspect of the present invention, the present invention also provides a use of an acrylic copolymer for water-based organic and inorganic pigment dispersion prepared by any of the preparation methods described above in water-based architectural coatings.

[0026] The beneficial effects of the present invention are:

[0027] The preparation process provided by the invention is simple, and the product is easy to obtain. The monomer conversion rate can be improved by changing the addition form of the initiator and real-time classification of the generated copolymerization reactants, so that the preparation efficiency of the acrylate copolymer is further improved. At the same time, the acrylate copolymer obtained by the preparation method of the invention has the characteristics of more uniform molecular structure and more stable performance, and has excellent dispersion stability for water-based organic and inorganic pigments. When the acrylate copolymer is applied to water-based architectural coatings, it has good dispersion effect and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the overall structure of the preparation device provided by the present invention;

[0029] Figure 2 A schematic diagram of the internal structure of a polymerization reactor provided by the present invention;

[0030] Figure 3 The present invention provides Figure 2 A magnified view of some structures in ;

[0031] Figure 4 This is a schematic structural diagram of the dispersed structure provided by the present invention.

[0032] In the figure: 1. Dissolving kettle 1; 2. Polymerization reactor; 21. Reactor body; 22. Partition; 23. Fixed bed; 24. Driving rotating unit; 25. Classifying unit; 251. Shell; 252. Liquid outlet; 253. Tubular separation element; 254. Swirl rod; 255. Connecting pipe; 256. External swirl blade; 257. Internal swirl blade; 258. Separation membrane; 3. Dissolving kettle 2; 4. Centrifugal separation unit; 5. Storage tank; 6. Atomizing unit; 7. Metering pumping unit 1; 8. Metering pumping unit 2; 9. Heat transfer oil circulation heating unit; 10. Circulating coil 1; 11. Circulating coil 2; 12. Dispersion structure; 121. Swirl plate; 122. Flow guide cover; 13. Supplementary pipeline. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Technicians in this field can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0034] Example 1

[0035] This embodiment provides a method for preparing an acrylic copolymer for aqueous organic and inorganic pigment dispersion.

[0036] The acrylic copolymer can be prepared from the following components in parts by weight: 60-90 parts by weight of a polymerizable monomer, 0.5-2 parts by weight of an initiator, 0.3-1.2 parts of a pH adjuster, 0.5-1.5 parts of a catalyst and 20-40 parts of an organic solvent, wherein the polymerizable monomer includes methacrylic acid, cyclobenzyl acrylate and tert-butylaminoethyl acrylate.

[0037] In this embodiment, the polymerizable monomer is preferably 90 parts, the initiator is preferably 2 parts, the catalyst is preferably 1.5 parts and the organic solvent is preferably 20-40 parts. Among the weight parts of the polymerizable monomer, the methacrylic acid is preferably 50 parts, the cyclobenzyl acrylate is preferably 25 parts and the tert-butylaminoethyl acrylate is preferably 15 parts.

[0038] The organic solvent may be one or two of ester and ketone solvents mixed in any ratio. In the present embodiment, the organic solvent is preferably ethyl formate and butyl acetate mixed in any ratio.

[0039] The catalyst is preferably a supported solid acid catalyst, and the initiator is preferably ammonium persulfate.

[0040] The method for preparing the acrylic acid ester copolymer comprises the following steps:

[0041] Step 1: dissolving the polymerization monomer and the initiator accounting for 40-50wt% of the total amount of the initiator, preferably 50wt% in this embodiment, in an organic solvent accounting for 40-50wt% of the total amount of the organic solvent, preferably 50wt% in this embodiment, to obtain a first solution;

[0042] Step 2: dissolving 30-40 wt% of the initiator, preferably 30 wt% in this embodiment, in an organic solvent, preferably 30 wt% in this embodiment, to obtain a second solution;

[0043] Step 3: first, the first solution obtained in step 1 is heated to 60-80° C. in the presence of a catalyst, preferably 80° C. in this embodiment, and then the second solution obtained in step 2 is uniformly added to the first solution in the form of atomization within 2-3 hours, preferably 2 hours in this embodiment, and then kept warm for 4-6 hours after the addition, preferably 4 hours in this embodiment, and the obtained products are graded in real time while being kept warm to obtain a primary product and a secondary product, and the remaining initiator and organic solvent are added to the secondary product, and the temperature is raised to 80-100° C., preferably 100° C. in this embodiment, and the temperature is continued to be kept warm, and after the end of the heat preservation, the primary product and the secondary product are mixed to obtain a polymerization reaction product;

[0044] Step 4: Centrifuge the polymerization product obtained in step 3 to obtain the acrylic acid ester copolymer.

[0045] Example 2

[0046] In order to better implement the preparation method disclosed in Example 1, this example further discloses a preparation device for water-based organic and inorganic pigment controllable acrylate.

[0047] like Figure 1 As shown, the preparation device includes a dissolving kettle 1 for preparing a first solution, a dissolving kettle 2 3 for preparing a second solution, and a storage tank 5 for storing acrylic copolymers. The dissolving kettle 1 and the dissolving kettle 2 3 have stirring structures themselves. The reaction raw materials are accurately weighed and transported to the dissolving kettle 1 and the dissolving kettle 2 3 through a conveying pipeline, and the reaction raw materials are evenly dispersed with the help of their own stirring structures.

[0048] The preparation device also includes a metering pumping unit 7 connected to the dissolving kettle 1, the dissolving kettle 2, and the supplementary pipeline 13 through pipelines, and is used to quantitatively transport the initiator and the organic solvent to the dissolving kettle 1, the dissolving kettle 2, and the supplementary pipeline 13.

[0049] Furthermore, if Figure 1 As shown, the preparation device also includes a heat transfer oil circulation heating unit 9, and a circulation coil 1 10 and a circulation coil 2 11 are respectively arranged inside the two compartments, and the two ends of the circulation coil 10 and the circulation coil 2 11 are respectively connected to the inlet and outlet liquid ends of the heat transfer oil circulation heating unit 9. The heat transfer oil flowing out of the heat transfer oil circulation heating unit 9 will heat the reaction chamber via the circulation coil 1 10 and the circulation coil 2 11, thereby providing the required temperature conditions in the two compartments.

[0050] The structure of the preparation device also includes a polymerization reactor 2 connected to the dissolving kettle 1 outlet through a pipeline connected in series with a metering pumping unit 2 8, wherein the polymerization reactor 2 is provided with a fixed bed 23 with a catalyst fixed therein and a classification unit 25 for real-time classification of the copolymerization reaction product to obtain a primary product and a secondary product, wherein the classification unit 25 has a primary reaction chamber and a secondary reaction chamber, and the secondary reaction chamber is connected to a supplementary pipeline 13;

[0051] Furthermore, if Figure 2 As shown, the polymerization reactor 2 includes a reactor body 21 and a driving rotating unit 24 for driving a classifying unit 25 to rotate. The interior of the reactor body 21 is provided with a partition 22 to form two compartments interconnected at the top. The fixed bed 23 and the classifying unit 25 are respectively arranged in the two compartments. The first solution enters the reaction chamber of the reactor body 21 from top to bottom, flows through the fixed bed 23 containing the catalyst, and the first solution is heated to 80°C in the presence of the catalyst, and then flows into the other compartment through the upper end of the compartment.

[0052] The structure of the preparation device also includes an atomizing unit 6 connected to the liquid outlet of the dissolving kettle 2 3 through a pipeline, and one end of the atomizing unit 6 extending into the polymerization reactor 2 is connected to a dispersing structure 12 arranged outside the grading unit 25. After the second solution enters the atomizing unit 6 and is atomized, it is dispersed into the compartment through the dispersing structure 12 and mixed with the first solution. Under the conditions of heating and the presence of an initiator, the polymerizable monomers in the first solution are copolymerized to generate copolymer reactants;

[0053] Furthermore, if Figure 4 As shown, the dispersion structure 12 includes a swirl plate 121 and a guide cover 122 that are relatively arranged. The swirl plate 121 is arranged opposite to the lower end opening of the guide cover 122. The feed port of the guide cover 122 is connected to the discharge port of the atomizing unit 6 through a pipeline. The atomized second solution flows to the swirl plate 121 under the guiding action of the guide cover 122 and is fully contacted with the first solution on the swirl plate 121. The first solution and the second solution flow along the outside of the grading unit 25 and copolymerize under heating conditions to obtain a copolymer reactant.

[0054] Subsequently, the copolymerization reactants are subjected to real-time classification processing under the operation of the classification unit 25, specifically, Figure 2-3 As shown, the classifying unit 25 comprises a housing 251, a liquid outlet 252 disposed in the middle of the housing 251, a swirl rod 254 disposed in the upper half of the housing 251, and a tubular separator 253 disposed in the lower half of the housing 251, wherein the lower end of the liquid outlet 252 is connected to the lower half of the housing 251, and a separation membrane 258 is disposed outside the tubular separator 253;

[0055] The top of the tubular separator 253 is provided with a connecting tube 255 connected to the upper half of the outer shell 251. The inner wall of the connecting tube 255 is provided with a built-in swirl blade 257 connected to the swirl rod 254. The outer wall of the connecting tube 255 is provided with an external swirl blade 256 at a position inside the liquid outlet 252.

[0056] The specific implementation method is as follows: the rotating unit 24 is driven to drive the swirl rod 254 and the tubular separator 253 to rotate synchronously, so that the copolymer reactants flowing into the compartment are sucked into the tubular separator 253 located in the lower half of the shell 251 from the lower end of the compartment. The tubular separator 253 generates centrifugal force when rotating, so that the copolymer (primary product) with a larger specific gravity flows through the separation membrane 258 into the shell 251, while the polymerized monomer (secondary product) that has not been polymerized in time will be sucked into the upper part of the shell 251 along the outer periphery of the swirl rod 254 through the built-in swirl blade 257 due to its smaller specific gravity. In the first half section, after the insulation is completed, the primary product will enter the liquid outlet 252, and when the connecting pipe 255 rotates, the external swirl blade 256 on the outside will rotate accordingly and will also swirl out the primary product in the liquid outlet 252, and then discharge the reactor body 21. The secondary product entering the upper half of the outer shell 251 is lifted by the rotation of the swirl rod 254. At the same time, the remaining organic solvent and initiator will enter the upper half of the outer shell 251 through the supplementary pipe 13, so that the secondary product will be further copolymerized. Subsequently, after the insulation is completed, the secondary product outlet of the outer shell 251 will be discharged from the reactor body 21.

[0057] Furthermore, the preparation device also includes a centrifugal separation unit 4 connected to the discharge port of the polymerization reactor 2 through pipelines, for centrifugally separating the polymerization reaction product consisting of the primary product and the secondary product. The discharge port of the centrifugal separation unit 4 is connected to the storage tank 5 through a pipeline, and the finally obtained acrylic ester copolymer is stored in the storage tank 5.

[0058] In order to further explore the effect of the preparation method on the properties of the obtained acrylic copolymer, the present invention further sets the following comparative examples:

[0059] Comparative Example 1

[0060] The difference from Example 1 is that the method for preparing the acrylic acid ester copolymer comprises the following steps:

[0061] Step 1: dissolving the polymerization monomer and 50 wt% of the initiator in 40-50 wt% of the organic solvent to obtain a first solution;

[0062] Step 2: dissolving 30 wt% of the initiator, preferably 30 wt% in this embodiment, in an organic solvent, preferably 30 wt% in this embodiment, to obtain a second solution;

[0063] Step 3: firstly, the first solution obtained in step 1 is heated to 80° C. in the presence of a catalyst, and then the second solution obtained in step 2 is uniformly added to the first solution in the form of atomization within 2 hours, and then the temperature is kept for 4 hours after the addition is completed. During the heat preservation process, the remaining initiator and organic solvent are added, and the temperature is raised to 100° C. After the heat preservation is completed, a polymerization reaction product is obtained;

[0064] Step 4: Centrifuge the polymerization product obtained in step 3 to obtain the acrylic acid ester copolymer.

[0065] Comparative Example 2

[0066] The preparation method of the acrylic acid ester copolymer disclosed in this comparative example comprises the following steps:

[0067] Step 1: dissolving the polymerization monomer and the initiator accounting for 50 wt % of the total amount of the initiator in an organic solvent accounting for 50 wt % of the total amount of the organic solvent to obtain a first solution;

[0068] Step 2: dissolving 30 wt% of the initiator in an organic solvent in an organic solvent in an organic solvent in a proportion of 30 wt% to obtain a second solution;

[0069] Step 3: firstly, the first solution obtained in step 1 is heated to 80° C. in the presence of a catalyst, and then the second solution obtained in step 2 is uniformly added to the first solution within 2 hours, and the temperature is kept for 4 hours after the addition is completed. While the temperature is kept, the obtained products are graded in real time to obtain a primary product and a secondary product, and the remaining initiator and organic solvent are added to the secondary product, and the temperature is raised to 100° C., and the temperature is continued to be kept, and after the temperature is kept, the primary product and the secondary product are mixed to obtain a polymerization reaction product;

[0070] Step 4: Centrifuge the polymerization product obtained in step 3 to obtain the acrylic acid ester copolymer.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that the preparation method of the acrylic acid ester copolymer disclosed in this comparative example comprises the following steps:

[0073] Step 1: dissolving a polymerization monomer and an initiator in an organic solvent to obtain a first solution;

[0074] Step 2: heating the first solution obtained in step 1 to 100° C. in the presence of a catalyst, and keeping the temperature for 6 hours, and obtaining a polymerization product after the temperature is maintained;

[0075] Step 3: Centrifuge the polymerization product obtained in step 3 to obtain the acrylic ester copolymer.

[0076] Verification test

[0077] (1) Calculation of monomer conversion and molecular weight distribution PDI

[0078] The monomer conversion rate of the acrylic ester copolymers prepared in Example 1 and Comparative Examples 1-3 was measured by weighing method, that is, monomer conversion rate = (mass of the acrylic ester copolymer after drying / total mass of the added polymerization monomers) × 100%.

[0079] The molecular weight of the acrylic copolymers prepared in Example 1 and Comparative Examples 1-3 was detected by MALDI-TOF mass spectrometry, and the molecular weight distribution index (PDI) of the acrylic copolymers was calculated based on the signal intensity data of MALDI-TOF.

[0080] The results are shown in Table 1.

[0081] Table 1. Monomer conversion and molecular weight distribution PDI

[0082]

[0083] As can be seen from Table 1, compared with Comparative Examples 1-3, the preparation method disclosed in Example 1 has a higher monomer conversion rate, the prepared acrylic copolymer has a lower molecular weight distribution, the molecular structure of the acrylic copolymer is more uniform, and the performance is more stable. The results in the table show that when preparing acrylic copolymers, changing the addition form of the initiator, that is, adopting a gradually reduced addition method while classifying the generated copolymerization reactants in real time, and timely separating the uncopolymerized polymerization monomers for supplementary polymerization, is conducive to further improving the monomer conversion rate, and the prepared acrylic copolymer has a more uniform molecular structure and more stable performance.

[0084] (2) Dispersion stability application test

[0085] The acrylate copolymers obtained in Example 1 and Comparative Examples 1-3 were subjected to dispersion stability test of water-based organic and inorganic pigments. In addition, a commercially available acrylic dispersant (brand model KMT-3004, amine value 36 mg KOH / g) was used as a control group, and the specific test process was as follows:

[0086] (a) Preparation of pigment dispersion system: prepare several 10 mL test tubes with stoppers, weigh 0.1 g of pigment and place it in each test tube, then weigh 0.8% of the pigment mass of dispersants a to e in a small beaker, add 10 mL of n-butanol to dissolve, pour the resulting solution into the above 10 mL test tubes, disperse in an ultrasonic machine for 30 min, and shake to obtain a pigment dispersion system. Repeat 3 times for each group. At the same time, a blank control group is used without any dispersant.

[0087] Carbon black C311 (organic pigment) and 4920 iron oxide yellow (inorganic pigment) were selected for testing.

[0088] (b) Place the prepared pigment dispersion system on a test tube rack and let it stand for 20 hours. Observe the sedimentation and record the position where the suspension settles. Calculate the dispersion force according to the following formula and take the average value of the result with 2 decimal places reserved:

[0089]

[0090] In the formula: h is the sedimentation height, mm; H is the total height, mm; F ​​is the dispersion force, %; the greater the dispersion force, the better the dispersibility.

[0091] The results are shown in Table 2.

[0092] Table 2. Results of dispersion stability application tests of water-based organic / inorganic pigments

[0093]

[0094] It can be seen from the table that the acrylic copolymer prepared in Example 1 has good dispersion stability for both the inorganic pigment 4920 iron oxide yellow and the organic pigment carbon black C311, which is better than the acrylic copolymers prepared in Comparative Examples 1-3 and the control group.

[0095] (3) Application test of water-based architectural coatings

[0096] The acrylic copolymers prepared in Example 1 and Comparative Examples 1-3 were used as dispersants to prepare the corresponding water-based architectural coatings. In addition, a commercially available acrylic dispersant (brand model KMT-3004, amine value 36 mg KOH / g) was used as a control group.

[0097] The preparation method of water-based interior wall construction primer is as follows: add water to the dispersion tank, start stirring, add cellulose, pigment wetting dispersant, defoamer, neutralizer, etc. in sequence and stir evenly, then add titanium dioxide, calcium carbonate, talcum powder, kaolin, and film-forming aid and stir at high speed until the fineness is qualified. Then slowly add styrene acrylic emulsion and other additives at a low stirring speed, stir until the slurry is evenly mixed to a suitable viscosity, and finally filter with a 100-mesh filter and package for use.

[0098] The experimental formula of interior wall building primer is shown in Table 3.

[0099] Table 3. Experimental formula of interior wall building primer

[0100]

[0101] (a) Contrast ratio test: According to the provisions of GB / T23981-2009, the interior wall building primer to which the acrylic copolymers of Example 1 and Comparative Examples 1-3 and the control group were added was film-formed on black and white cardboard, and after standard curing, the contrast ratio was tested.

[0102] (b) Analysis of dispersion effect: The dispersants of Example 1, Comparative Examples 1-3 and the control group were applied to the pigment dispersion part (Table 3) in the interior wall building primer formula to evaluate the dispersion results. The dispersion effect was judged by the viscosity of the slurry prepared from the pigment dispersion part. The smaller the viscosity, the better the dispersion effect, and vice versa. The results are shown in Table 4.

[0103] Table 4. Statistical table of water-based architectural coating application test results

[0104]

[0105] As can be seen from Table 4, compared with Comparative Examples 1-3 and the control group, Example 1 has a significant improvement in the contrast ratio of the interior wall architectural coating, and the dispersion effect is better than that of Comparative Examples 1-3 and the control group. The preparation method disclosed in Example 1 makes the dispersant have an advantage in molecular weight distribution, and thus has a better performance in improving the white contrast ratio and dispersion effect of the interior wall architectural primer. Therefore, the acrylate copolymer prepared in Example 1 has a good application prospect in the field of water-based architectural coatings.

[0106] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing an acrylic copolymer for aqueous organic and inorganic pigment dispersion, characterized in that: The acrylic copolymer is prepared from the following components in parts by weight: 60-90 parts of polymerizable monomers, 0.5-2 parts of initiators, 0.5-1.5 parts of catalysts, and 20-40 parts of organic solvents, wherein the polymerizable monomers include methacrylic acid, cyclobenzyl acrylate, and tert-butylaminoethyl acrylate; The method for preparing the acrylic acid ester copolymer comprises the following steps: Step 1: dissolving the polymerization monomer and the initiator accounting for 40-50 wt % of the total amount of the initiator in an organic solvent accounting for 40-50 wt % of the total amount of the organic solvent to obtain a first solution; Step 2: dissolving 30-40 wt % of the initiator in an organic solvent ... Step 3: firstly, the first solution obtained in step 1 is heated to 60-80° C. in the presence of a catalyst, and then the second solution obtained in step 2 is uniformly added to the first solution in the form of atomization within 2-3 hours, and then the temperature is kept for 4-6 hours after the addition is completed. While the temperature is kept, the obtained products are graded in real time to obtain a primary product and a secondary product, and the remaining initiator and organic solvent are added to the secondary product, and the temperature is raised to 80-100° C., and the temperature is continued to be kept, and after the temperature is kept, the primary product and the secondary product are mixed to obtain a polymerization reaction product; Step 4: Centrifuge the polymerization product obtained in step 3 to obtain the acrylic acid ester copolymer.

2. The method for preparing an aqueous acrylic copolymer for dispersing organic and inorganic pigments according to claim 1, characterized in that: The organic solvent is one or two of ester and ketone solvents mixed in any ratio, the catalyst is a supported solid acid catalyst, and the initiator is ammonium persulfate, potassium persulfate or sodium persulfate.

3. The method for preparing the aqueous acrylic copolymer for organic and inorganic pigment dispersion according to claim 1, characterized in that: In the weight parts of the polymerizable monomers, the methacrylic acid accounts for 40-50 parts, the cyclobenzyl acrylate accounts for 10-25 parts, and the tert-butylaminoethyl acrylate accounts for 10-15 parts.

4. An acrylic copolymer for aqueous organic and inorganic pigment dispersion prepared by the preparation method according to any one of claims 1 to 3.

5. A preparation device for an acrylic ester copolymer for aqueous organic and inorganic pigment dispersion as claimed in claim 4, comprising a dissolving kettle 1 (1) for preparing a first solution, a dissolving kettle 2 (3) for preparing a second solution and a storage tank (5) for storing the acrylic ester copolymer, characterized in that: Also includes: A polymerization reactor (2) connected to the discharge port of the dissolving kettle (1) through a pipeline connected in series with a metering pumping unit (8), wherein a fixed bed (23) having a catalyst fixed thereon and a classification unit (25) for classifying the copolymerization product in real time to obtain a primary product and a secondary product are arranged inside the polymerization reactor (2), wherein the classification unit (25) has a primary reaction chamber and a secondary reaction chamber, and the secondary reaction chamber is connected to a supplementary pipeline (13); An atomizing unit (6) is connected to the liquid outlet of the second dissolving kettle (3) through a pipeline, and one end of the atomizing unit (6) extending into the polymerization reactor (2) is connected to a dispersion structure (12) arranged outside the classification unit (25); A metering pumping unit (7) connected to the dissolving tank (1), the dissolving tank (3) and the supplementary pipeline (13) through pipelines, and used for quantitatively conveying the initiator and the organic solvent to the dissolving tank (1), the dissolving tank (3) and the supplementary pipeline (13); and a centrifugal separation unit (4) connected to the discharge ports of the polymerization reactor (2) through pipelines, for centrifugally separating the polymerization reaction product; the discharge port of the centrifugal separation unit (4) is connected to the storage tank (5) through a pipeline.

6. The device for preparing the acrylic copolymer for aqueous organic and inorganic pigment dispersion according to claim 5, characterized in that: The polymerization reactor (2) comprises a reactor body (21) and a driving rotating unit (24) for driving a classifying unit (25) to rotate. The interior of the reactor body (21) is provided with a partition (22) to form two compartments interconnected at the top ends. The fixed bed (23) and the classifying unit (25) are respectively arranged in the two compartments.

7. The device for preparing an acrylic copolymer for aqueous organic and inorganic pigment dispersion according to claim 5, characterized in that: The classifying unit (25) comprises a housing (251), a liquid outlet member (252) disposed in the middle of the housing (251), a swirl rod member (254) disposed in the upper half of the housing (251), and a tubular separator (253) disposed in the lower half of the housing (251); the lower end of the liquid outlet member (252) is connected to the lower half of the housing (251); and a separation membrane (258) is disposed on the outside of the tubular separator (253); A connecting tube (255) connected to the upper half of the outer shell (251) is provided at the top end of the tubular separator (253); an inner wall of the connecting tube (255) is provided with a built-in swirl blade (257) connected to the swirl rod (254); and an outer wall of the connecting tube (255) is provided with an external swirl blade (256) at a position inside the liquid outlet (252).

8. The device for preparing an aqueous acrylic copolymer for dispersing organic and inorganic pigments according to claim 6, characterized in that: The preparation device also includes a heat transfer oil circulation heating unit (9), and the two compartments are respectively provided with a circulation coil one (10) and a circulation coil two (11), and the two ends of the circulation coil one (10) and the circulation coil two (11) are respectively connected to the liquid inlet and outlet ends of the heat transfer oil circulation heating unit (9).

9. The device for preparing an aqueous acrylic copolymer for dispersing organic and inorganic pigments according to claim 1, characterized in that: The dispersion structure (12) comprises a swirl plate (121) and a flow guide cover (122) which are arranged opposite to each other, the swirl plate (121) being arranged opposite to the lower opening of the flow guide cover (122), and the feed inlet of the flow guide cover (122) being connected to the discharge outlet of the atomizing unit (6) via a pipeline.

10. Use of an acrylic copolymer for water-based organic and inorganic pigment dispersion prepared by the preparation method according to any one of claims 1 to 3 in water-based architectural coatings.

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