Preparation Method of Acrylate Copolymer for Dispersing Water-based Organic and Inorganic Pigments

Abstract

The present invention discloses a preparation method of an acrylate copolymer for dispersing water-based organic and inorganic pigments, which relates to the technical field of preparing acrylate dispersants. The preparation process provided by the present invention is simple, and the product is easy to obtain. By changing the addition form of the initiator and performing real-time grading on the generated copolymerization reactants, the monomer conversion rate can be increased, further improving the preparation efficiency of the acrylate copolymer. At the same time, the acrylate copolymer obtained by the preparation method of the present invention has the characteristics of a more uniform molecular structure and more stable performance, excellent dispersion stability for water-based organic and inorganic pigments, and has a good dispersion effect when applied to water-based architectural coatings, with good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of acrylate dispersants, and particularly relates to a preparation method of an acrylate copolymer for aqueous organic and inorganic pigment dispersion. Background Art

[0002] With the new development needs of architectural coating technology, the refined requirements for various functional additives used in coatings are getting higher and higher. In architectural coating production technology, pigment dispersion is an important link in coating manufacturing technology. Pigment dispersion refers to the process in which the secondary agglomerates of pigments are wetted 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 surface replacement of pigments, and its main purpose is to reduce the interfacial tension of substances. Dispersion is the process in which the aggregates of pigments are separated under the action of external forces; stabilization is the process in which pigments no longer flocculate after dispersion. The addition of a dispersant can promote better wetting of water on the pigment surface, produce different affinity anchoring binding methods with the pigment surface, and form a stability among the pigment-dispersant-system. The main action modes of pigment dispersion stability are through steric hindrance and charge effects, and these action modes are the determining factors for the stability of pigments in aqueous architectural coating systems.

[0003] Dispersants applied in aqueous coatings are usually divided into three categories: inorganic salts, surfactants, and high molecular compounds. In modern architectural coating formulations, inorganic salts and surfactant dispersants are not used as the main dispersants in aqueous architectural coatings, and high molecular acrylic compounds are currently the commonly used dispersants in architectural coatings. Among them, acrylate copolymers are a type of widely used polymer dispersant. Therefore, optimizing and improving the molecular structure and dispersion performance of acrylate copolymers has positive significance for promoting their use effects in aqueous architectural coatings. Summary of the Invention

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

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

[0006] As a first aspect of the present invention, the present invention provides a preparation method of an acrylate copolymer for aqueous organic and inorganic pigment dispersion. The acrylate copolymer is prepared from the following components in parts by weight: 60-90 parts of polymerization monomers, 0.5-2 parts of initiator, 0.5-1.5 parts of catalyst, and 20-40 parts of organic solvent, wherein the polymerization monomers include methacrylic acid, cyclohexylbenzyl acrylate, and tert-butylaminoethyl acrylate;

[0007] The preparation method of the acrylate copolymer comprises the following steps:

[0008] Step 1: Dissolve the polymerization monomers and 40-50 wt% of the total initiator in 40-50 wt% of the total organic solvent to obtain a first solution;

[0009] Step 2: Dissolve 30-40 wt% of the total initiator in 30-40 wt% of the total organic solvent to obtain a second solution;

[0010] Step 3: First, heat the first solution obtained in Step 1 to 60-80 °C in the presence of a catalyst, and then uniformly add the second solution obtained in Step 2 to the first solution in an atomized form within 2-3 h. After the addition, keep warm for 4-6 h. During the warming, perform real-time fractionation on the obtained product to obtain a primary product and a secondary product. Add the remaining initiator and organic solvent to the secondary product, heat to 80-100 °C, and continue to keep warm. After the warming ends, mix the primary product and the secondary product to obtain a polymerization reaction product;

[0011] Step 4: Centrifuge the polymerization reaction product obtained in Step 3 to obtain the acrylate copolymer.

[0012] As a further optimized scheme of the present invention, the organic solvent is one or two of ester solvents 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 optimized scheme of the present invention, among the weight parts of the polymerization monomers, 40-50 parts of methacrylic acid, 10-25 parts of cyclohexyl benzyl acrylate and 10-15 parts of tert-butylaminoethyl acrylate are included.

[0014] As a second aspect of the present invention, the present invention also provides an acrylate copolymer for water-based organic-inorganic pigment dispersion prepared by the preparation method described in any one of the above.

[0015] As a third aspect of the present invention, the present invention also provides a preparation device for an acrylate copolymer for water-based organic-inorganic pigment dispersion described in any one of the above, including a first dissolution tank for preparing the first solution, a second dissolution tank for preparing the second solution, and a storage tank for storing the acrylate copolymer, and further including:

[0016] A polymerization reactor connected to a first dissolving kettle outlet via a pipeline connected in series with a second metering pumping unit, wherein the polymerization reactor is provided with a fixed bed having a catalyst fixed therein and a classification unit for real-time classification of the copolymerization reaction product to obtain a primary product and a secondary product, wherein the classification unit has a primary reaction chamber and a secondary reaction chamber, and the secondary reaction chamber is connected to a replenishing pipeline;

[0017] An atomizing unit is connected to the second liquid outlet of the dissolving kettle through a pipeline, and 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 is connected to the dissolving tank 1, the dissolving tank 2 and the supplementary pipeline respectively through pipelines, and is used to quantitatively transport the initiator and the organic solvent to the dissolving tank 1, the dissolving tank 2 and the supplementary pipeline;

[0019] and centrifugal separation units respectively connected to the discharge ports of the polymerization reactors through pipelines, for centrifugally separating the polymerization reaction products; the discharge ports of the centrifugal separation units are connected to the storage tanks through pipelines.

[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 solution of the present invention, the classifying unit includes a housing, a liquid outlet member provided in the middle of the housing, a swirl rod provided in the upper half of the housing, and a tubular separator provided in the lower half of the housing, wherein the lower end of the liquid outlet member is connected to the lower half of the housing, and a separation membrane is provided on the outside of 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 side wall of the connecting pipe is provided with a built-in swirl blade connected to the swirl rod, and the outer side 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 thermal oil circulation heating unit, and the two compartments are respectively provided with a circulation coil 1 and a circulation coil 2, and the two ends of the circulation coil 1 and the circulation coil 2 are respectively connected to the inlet and outlet liquid ends of the thermal 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 arranged relatively, 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 atomizing unit through a pipeline.

[0025] As a second aspect of the present invention, the present invention also provides an application of an acrylate copolymer prepared by the preparation method described in any one of the above in water-based architectural coatings for dispersing water-based organic and inorganic pigments.

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

[0027] The preparation process provided by the present invention is simple, and the product is easy to obtain. By changing the addition form of the initiator and performing real-time grading on the generated copolymerization reactants, the monomer conversion rate can be increased, further improving the preparation efficiency of the acrylate copolymer. At the same time, the acrylate copolymer obtained by the preparation method of the present invention has the characteristics of a more uniform molecular structure and more stable performance, excellent dispersion stability for water-based organic and inorganic pigments, and has a good dispersion effect when applied to water-based architectural coatings, with good application prospects. Description of the Drawings

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

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

[0030] Figure 3 provided by the present invention Figure 2 is an enlarged view of a partial structure in;

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

[0032] In the figure: 1, the first dissolving kettle; 2, the polymerization reactor; 21, the reactor main body; 22, the partition member; 23, the fixed bed; 24, the driving rotation unit; 25, the grading unit; 251, the outer shell; 252, the liquid outlet member; 253, the tubular separation member; 254, the swirl rod member; 255, the connecting pipe; 256, the external swirl blade; 257, the internal swirl blade; 258, the partition membrane; 3, the second dissolving kettle; 4, the centrifugal separation unit; 5, the storage tank; 6, the atomization unit; 7, the first metering pumping unit; 8, the second metering pumping unit; 9, the heat transfer oil circulation heating unit; 10, the first circulation coil; 11, the second circulation coil; 12, the dispersion structure; 121, the swirl plate member; 122, the flow guide cover; 13, the supplementary pipeline. Detailed Embodiments

[0033] The present invention will be further described in detail below with reference to the drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0034] Example 1

[0035] This example provides a preparation method of an acrylate copolymer for aqueous organic-inorganic pigment dispersion.

[0036] The acrylate copolymer can be prepared from the following components in parts by weight: 60 - 90 parts by weight of polymerization monomers, 0.5 - 2 parts by weight of initiator, 0.3 - 1.2 parts of pH regulator, 0.5 - 1.5 parts of catalyst, and 20 - 40 parts of organic solvent. Among them, the polymerization monomers include methacrylic acid, cyclohexylbenzyl acrylate, and tert-butylaminoethyl acrylate.

[0037] In this example, the polymerization monomers are 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 parts by weight of the polymerization monomers, the methacrylic acid is preferably 50 parts, the cyclohexylbenzyl acrylate is preferably 25 parts, and the tert-butylaminoethyl acrylate is preferably 15 parts.

[0038] The organic solvent can be one or a mixture of two of ester solvents and ketone solvents in any ratio. In this example, the organic solvent is preferably a mixture of ethyl formate and butyl acetate in any ratio.

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

[0040] The preparation method of the acrylate copolymer includes the following steps:

[0041] Step 1: Dissolve the polymerization monomers and 40 - 50 wt% of the initiator, preferably 50 wt% in this example, in 40 - 50 wt% of the organic solvent, preferably 50 wt% in this example, to obtain a first solution.

[0042] Step 2: Dissolve 30 - 40 wt% of the initiator, preferably 30 wt% in this example, in 30 wt% of the organic solvent, preferably 30 wt% in this example, to obtain a second solution.

[0043] Step 3: First, heat the first solution obtained in Step 1 to 60 - 80°C in the presence of a catalyst. In this example, it is preferably 80°C. Then, within 2 - 3 h, preferably 2 h in this example, add the second solution obtained in Step 2 to the first solution in a uniform atomized form. After adding, keep it warm for 4 - 6 h, preferably 4 h in this example. While keeping it warm, perform real-time classification on the obtained product to obtain a primary product and a secondary product. Add the remaining initiator and organic solvent to the secondary product, heat it to 80 - 100°C, preferably 100°C in this example, and continue to keep it warm. After the heat preservation ends, mix the primary product and the secondary product to obtain a polymerization reaction product;

[0044] Step 4: Centrifuge the polymerization reaction product obtained in Step 3 to obtain the acrylate copolymer.

[0045] Example 2

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

[0047] As Figure 1 shown, the preparation device includes a first dissolving kettle 1 for preparing the first solution, a second dissolving kettle 3 for preparing the second solution, and a storage tank 5 for storing the acrylate copolymer. The first dissolving kettle 1 and the second dissolving kettle 3 have their own stirring structures. The reaction raw materials are accurately weighed and transported through the conveying pipeline to the first dissolving kettle 1 and the second dissolving kettle 3, and the uniform dispersion of the reaction raw materials is achieved by means of their own stirring structures.

[0048] The preparation device further includes a metering pump unit 7 connected to the first dissolving kettle 1, the second dissolving kettle 3, and the supplementary pipeline 13 through pipelines, which is used to quantitatively transport the initiator and the organic solvent to the first dissolving kettle 1, the second dissolving kettle 3, and the supplementary pipeline 13.

[0049] Further, as Figure 1 shown, the preparation device further includes a heat-conducting oil circulation heating unit 9. In the two partition chambers, a first circulation coil 10 and a second circulation coil 11 are respectively arranged. The two ends of the first circulation coil 10 and the second circulation coil 11 are respectively connected to the inlet and outlet ends of the heat-conducting oil circulation heating unit 9. The heat-conducting oil flowing out of the heat-conducting oil circulation heating unit 9 will heat the reaction chamber through the first circulation coil 10 and the second circulation coil 11 to provide the required temperature conditions in the two partition chambers.

[0050] The structure of the preparation device further includes a polymerization reactor 2 connected to the discharge port of the first dissolution kettle 1 through a pipeline in series with a metering pump unit 8. Inside the polymerization reactor 2, there is a fixed bed 23 with a catalyst fixed thereon and a grading unit 25 for real-time grading of the copolymerization reaction product to obtain a primary product and a secondary product. The grading unit 25 has a primary reaction chamber and a secondary reaction chamber, and the secondary reaction chamber is connected with a supplementary pipeline 13;

[0051] Further, as Figure 2 shown, the polymerization reactor 2 includes a reactor main body 21 and a driving rotation unit 24 for driving the grading unit 25 to rotate. Inside the reactor main body 21, two separated chambers with interconnected tops are formed by arranging a separating member 22. The fixed bed 23 and the grading unit 25 are respectively arranged in the two separated chambers. The first solution enters the reaction chamber of the reactor main 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 another separated chamber through the upper end of the separated chamber.

[0052] The structure of the preparation device further includes an atomization unit 6 connected to the liquid outlet of the second dissolution kettle 3 through a pipeline. One end of the atomization unit 6 extending into the polymerization reactor 2 is connected with a dispersion structure 12 arranged outside the grading unit 25. The second solution enters the atomization unit 6, is atomized, and then is dispersed into the separated chamber through the dispersion structure 12 to be mixed with the first solution. In the presence of heating and an initiator, the polymerization monomers in the first solution generate copolymerization to form a copolymerization reactant;

[0053] Further, as Figure 4 shown, the dispersion structure 12 includes a swirl plate member 121 and a flow guide cover 122 arranged oppositely. The swirl plate member 121 is arranged opposite to the lower end opening of the flow guide cover 122. The feed port of the flow guide cover 122 is connected to the discharge port of the atomization unit 6 through a pipeline. The atomized second solution flows to the swirl plate member 121 under the guiding action of the flow guide cover 122 to achieve full contact with the first solution on the swirl plate member 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 copolymerization reactant.

[0054] Subsequently, the copolymerization reactant is subjected to real-time grading treatment under the operation of the grading unit 25. Specifically, as Figure 2-3 shown, the grading unit 25 includes a housing 251, a liquid outlet member 252 arranged in the middle of the housing 251, a swirl rod member 254 arranged in the upper half of the housing 251, and a tubular separation member 253 arranged in the lower half of the housing 251. The lower end of the liquid outlet member 252 is communicated with the lower half of the housing 251. A separation membrane 258 is arranged outside the tubular separation member 253;

[0055] The top end of the tubular separator 253 is provided with a connecting pipe 255 that communicates with the upper half of the outer shell 251. The inner side wall of the connecting pipe 255 is provided with an internal swirl vane 257 connected to the swirl rod member 254. The outer side wall of the connecting pipe 255 at the position inside the liquid outlet member 252 is provided with an external swirl vane 256.

[0056] The specific implementation method is as follows: The driving unit 24 drives the swirl rod member 254 and the tubular separator 253 to rotate synchronously, so that the copolymerization reactant flowing into the partition chamber is sucked from the lower end of the partition chamber into the tubular separator 253 located in the lower half of the outer shell 251. When the tubular separator 253 rotates, a centrifugal force is generated, so that the copolymer (primary product) that has been copolymerized and has a larger specific gravity passes through the partition membrane 258 and flows into the outer shell 251. The polymerization monomer (secondary product) that has not been polymerized in time will be sucked into the upper half of the outer shell 251 along the outer periphery of the swirl rod member 254 and swirl through the internal swirl vane 257 due to its smaller specific gravity. After the primary product is kept warm, it will enter the liquid outlet member 252. When the connecting pipe 255 rotates, the external swirl vane 256 on its outer side will rotate accordingly and will spin out the primary product in the liquid outlet member 252 together, and then discharge it from the reactor main body 21. The secondary product entering the upper half of the outer shell 251 is lifted under the swirling action of the swirl rod member 254. At the same time, the remaining organic solvent and initiator will enter the upper half of the outer shell 251 through the supply pipe 13, so that the secondary product is further copolymerized. Then, after the heat preservation is completed, it is discharged from the reactor main body 21 through the secondary product outlet of the outer shell 251.

[0057] Furthermore, the preparation device further includes a centrifugal separation unit 4 connected to the discharge port of the polymerization reactor 2 through pipelines, which is used for centrifugally separating the polymerization reaction product composed 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 acrylate copolymer is stored in the storage tank 5.

[0058] To further explore the influence of the preparation method on the performance of the obtained acrylate copolymer, the present invention further sets the following comparative examples:

[0059] Comparative Example 1

[0060] The difference from Example 1 is that the preparation method of the acrylate copolymer includes the following steps:

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

[0062] Step 2: Dissolve 30 wt% of the initiator, preferably 30 wt% in this example, in 30 wt% of the organic solvent, preferably 30 wt% in this example, based on the total amount of the organic solvent, to obtain a second solution;

[0063] Step 3: First, heat the first solution obtained in Step 1 to 80 °C in the presence of a catalyst, and then uniformly add the second solution obtained in Step 2 to the first solution in the form of atomization within 2 h. After addition, keep the temperature for 4 h, and add the remaining initiator and organic solvent during the heat preservation process, then heat up to 100 °C. After the heat preservation ends, a polymerization reaction product is obtained;

[0064] Step 4: Centrifuge the polymerization reaction product obtained in Step 3 to obtain the acrylate copolymer.

[0065] Comparative Example 2

[0066] The preparation method of the acrylate copolymer disclosed in this comparative example includes the following steps:

[0067] Step 1: Dissolve the polymerization monomer and 50 wt% of the initiator based on the total amount of the initiator in 50 wt% of the organic solvent based on the total amount of the organic solvent to obtain a first solution;

[0068] Step 2: Dissolve 30 wt% of the initiator based on the total amount of the initiator in 30 wt% of the organic solvent based on the total amount of the organic solvent to obtain a second solution;

[0069] Step 3: First, heat the first solution obtained in Step 1 to 80 °C in the presence of a catalyst, and then uniformly add the second solution obtained in Step 2 to the first solution within 2 h. After addition, keep the temperature for 4 h, and perform real-time fractionation on the obtained product during the heat preservation to obtain a primary product and a secondary product. Add the remaining initiator and organic solvent to the secondary product, heat up to 100 °C, and continue to keep the temperature. After the heat preservation ends, mix the primary product and the secondary product to obtain a polymerization reaction product;

[0070] Step 4: Centrifuge the polymerization reaction product obtained in Step 3 to obtain the acrylate copolymer.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that the preparation method of the acrylate copolymer disclosed in this comparative example includes the following steps:

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

[0074] Step 2: Heat the first solution obtained in Step 1 to 100 °C in the presence of a catalyst, keep the temperature for 6 h, and obtain a polymerization reaction product after the heat preservation is completed;

[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 rate and molecular weight distribution PDI

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

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

[0080] The results are shown in Table 1.

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

[0082]

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

[0084] (2) Application test of dispersion stability

[0085] The acrylic ester copolymers obtained in Example 1 and Comparative Examples 1-3 were subjected to an application test of the dispersion stability 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 into each test tube, then successively weigh dispersants a - e accounting for 0.8% of the pigment mass into a small beaker, add 10 mL of n-butanol to dissolve, pour the obtained solution into the above 10 mL test tubes, disperse in an ultrasonic machine for 30 min, shake well to obtain the pigment dispersion system. Each group is repeated 3 times. At the same time, use the group without adding any dispersant as the blank control group.

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

[0088] (b) Place the prepared pigment dispersion system on a test tube rack, let it stand for 20 h, observe the sedimentation situation, record the position where the suspension sediments, calculate the dispersing power according to the following formula, and take the average value of the results, retaining 2 decimal places:

[0089]

[0090] In the formula: h is the sedimentation height, in mm; H is the total height, in mm; F is the dispersing power, in %; the greater the dispersing power, the better the dispersibility.

[0091] The results are shown in Table 2.

[0092] Table 2. Application test results of the dispersion stability of waterborne organic / inorganic pigments

[0093]

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

[0095] (3) Application test of waterborne architectural coatings

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

[0097] The preparation method of the waterborne interior wall architectural primer is as follows: Add water to the dispersion tank, start stirring, successively add cellulose, pigment wetting and dispersing agent, defoamer, neutralizer, etc., stir evenly, then add titanium dioxide, calcium carbonate, talc powder, kaolin, 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 mixed evenly to a suitable viscosity, and finally filter with a 100-mesh sieve and package for standby.

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

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

[0100]

[0101] (a) Contrast ratio test: In accordance with the provisions of GB / T23981-2009, the interior wall architectural primers containing the acrylate copolymer of Example 1 and Comparative Examples 1-3 and the control group were film-formed on black and white cardboard. After standard curing, the contrast ratio was tested.

[0102] (b) Dispersion effect analysis: The dispersants of Example 1, Comparative Examples 1-3 and the control group were applied to the pigment dispersion part (Table 3) of the interior wall architectural primer formula for evaluating 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 application test results of waterborne architectural coatings

[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 in terms of the dispersion effect compared with Comparative Examples 1-3 and the control group, the preparation method disclosed in Example 1 gives the dispersant 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 waterborne architectural coatings.

[0106] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. Preparation method of acrylate copolymer for aqueous organic-inorganic pigment dispersion, characterized in that, The acrylate copolymer is prepared from the following components in parts by weight: 90 parts of polymerization monomers, 0.5 - 2 parts of initiator, 0.5 - 1.5 parts of catalyst, and 20 - 40 parts of organic solvent. Among them, in the parts by weight of the polymerization monomers, the polymerization monomers include 50 parts of methacrylic acid, 25 parts of cyclohexyl benzyl acrylate, and 15 parts of tert-butylaminoethyl acrylate; The preparation method of the acrylate copolymer includes the following steps: Step 1: Dissolve the polymerization monomers and 40 - 50 wt% of the initiator in 40 - 50 wt% of the organic solvent to obtain a first solution; Step 2: Dissolve 30 - 40 wt% of the initiator in 30 - 40 wt% of the organic solvent to obtain a second solution; Step 3: First, heat the first solution obtained in Step 1 to 60 - 80 °C in the presence of a catalyst, then uniformly add the second solution obtained in Step 2 to the first solution in the form of atomization within 2 - 3 h. After adding, keep warm for 4 - 6 h. During the warming, perform real-time grading on the obtained product to obtain a primary product and a secondary product. Add the remaining initiator and organic solvent to the secondary product, heat to 80 - 100 °C, and continue to keep warm. After the warming ends, mix the primary product and the secondary product to obtain a polymerization reaction product; Step 4: Centrifuge the polymerization reaction product obtained in Step 3 to obtain the acrylate copolymer.

2. The preparation method of the acrylate copolymer for aqueous organic-inorganic pigment dispersion according to claim 1, characterized in that, The organic solvent is one or a mixture of two of ester solvents and ketone solvents in any ratio. The catalyst is a supported solid acid catalyst, and the initiator is ammonium persulfate, potassium persulfate, or sodium persulfate.

3. An acrylate copolymer for water-based organic-inorganic pigment dispersion prepared by the preparation method according to any one of claims 1 - 2.

4. An apparatus for preparing an acrylate copolymer for aqueous organic-inorganic pigment dispersion as described in claim 3, comprising a first dissolving kettle (1) for preparing a first solution, a second dissolving kettle (3) for preparing a second solution, and a storage tank (5) for storing the acrylate copolymer, characterized in that, It further includes: A polymerization reactor (2) connected to the discharge port of a dissolution kettle (1) through a pipeline in series with a metering pump unit two (8). Inside the polymerization reactor (2), there is a fixed bed (23) fixed with a catalyst and a grading unit (25) for real-time grading of the copolymerization reaction product to obtain a primary product and a secondary product. The grading unit (25) has a primary reaction chamber and a secondary reaction chamber, and the secondary reaction chamber is connected with a supplementary pipeline (13); The grading unit (25) includes a housing (251), a liquid outlet member (252) provided in the middle of the housing (251), a swirling rod member (254) provided in the upper half of the housing (251), and a tubular separation member (253) provided inside the lower half of the housing (251). The lower end of the liquid outlet member (252) is communicated with the lower half of the housing (251). A partition membrane (258) is provided outside the tubular separation member (253). A communication pipe (255) connecting the upper half of the housing (251) is provided at the top of the tubular separation member (253). An internal swirling blade (257) connected to the swirling rod member (254) is provided on the inner side wall of the communication pipe (255). An external swirling blade (256) is provided at a position of the outer side wall of the communication pipe (255) inside the liquid outlet member (252); The polymerization reactor (2) includes a reactor main body (21) and a driving rotation unit (24) for driving the classification unit (25) to rotate. Inside the reactor main body (21), two partition chambers with interconnected tops are formed by arranging partition members (22). The fixed bed (23) and the classification unit (25) are respectively arranged in the two partition chambers; The atomization unit (6) connected to the liquid outlet of the second dissolution kettle (3) through a pipeline. One end of the atomization unit (6) extending into the polymerization reactor (2) is connected to a dispersion structure (12) arranged outside the classification unit (25); The metering pump unit one (7) connected to the first dissolution kettle (1), the second dissolution kettle (3) and the supplementary pipeline (13) through pipelines, which is used to quantitatively transport initiators and organic solvents into the first dissolution kettle (1), the second dissolution kettle (3) and the supplementary pipeline (13); And a centrifugal separation unit (4) connected to the discharge port of the polymerization reactor (2) through a pipeline, which is used to perform centrifugal separation on the polymerization reaction product. The discharge port of the centrifugal separation unit (4) is connected to the storage tank (5) through a pipeline.

5. The preparation apparatus of the acrylate copolymer for aqueous organic-inorganic pigment dispersion according to claim 4, characterized in that, The preparation device further includes a heat transfer oil circulation heating unit (9). A first circulation coil (10) and a second circulation coil (11) are respectively arranged inside the two partition chambers. The two ends of the first circulation coil (10) and the second circulation coil (11) are respectively connected to the liquid inlet and outlet ends of the heat transfer oil circulation heating unit (9).

6. The preparation device of the acrylate copolymer for aqueous organic-inorganic pigment dispersion according to claim 4, characterized in that, The dispersion structure (12) includes a swirl plate member (121) and a flow guide cover (122) arranged oppositely. The swirl plate member (121) is arranged opposite to the lower end opening of the flow guide cover (122). The feed port of the flow guide cover (122) is connected to the discharge port of the atomization unit (6) through a pipeline.

7. Application of an acrylate copolymer for dispersing water-based organic-inorganic pigments prepared by the preparation method according to any one of claims 1-2 in water-based architectural coatings.

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