Carboxylated acrylate-styrene copolymer microspheres, methods of making, systems, and applications thereof

Abstract

The present application relates to the field of polymer synthesis, and relates to a carboxylated acrylate-styrene copolymer microsphere and a preparation method, system and application thereof.The method comprises the following steps: S1, uniformly mixing a first mixed solution and a second mixed solution to obtain a raw material solution; S2, uniformly mixing the raw material solution and an initiator to obtain a reaction solution, and performing a polymerization reaction on the reaction solution in a tubular reactor to obtain a carboxylated acrylate-styrene copolymer microsphere; wherein the first mixed solution contains styrene, acrylate and a first dispersion medium; the second mixed solution contains a carboxyl functional monomer and a second dispersion medium; and the first dispersion medium and the second dispersion medium are both water.The preparation method is simple and continuous, the addition proportion of materials can be conveniently adjusted, and no stabilizer or surfactant is added in the preparation process, so that the obtained polymer microsphere has a suitable particle size, a clean surface, a narrow particle size distribution and can be used as a redispersible rubber powder.

Description

Technical Field

[0001] This invention relates to the field of polymer synthesis, specifically to a carboxylated acrylate-styrene copolymer microsphere, its preparation method, system, and application. Background Technology

[0002] Functional polymer microspheres with carboxyl groups on their surface can be used to prepare functional materials with different structures and properties, and these materials have many applications in adsorption, catalysis and biomedicine. Typically, carboxyl-containing polymer microspheres are prepared by copolymerizing monomers with carboxyl-containing monomers such as acrylic acid, methacrylic acid, or maleic anhydride. Common polymerization methods include suspension polymerization, emulsion polymerization, dispersion polymerization and precipitation polymerization. The preparation process usually involves stirring in a batch reactor to prepare carboxyl-containing polymer microspheres. For example, Yan Gongqin, Guan Jianguo, Gan Zhiping, Preparation and Characterization of Monodisperse P(St-co-AA) Microspheres, Polymer Materials Science and Engineering, 2007, 23(1):222-225. Functional microspheres can also be prepared by surface graft polymerization, using acrylic acid as a modifier, and grafting it onto polystyrene using soap-free emulsion polymerization to obtain functional microspheres with carboxyl groups on their surface. For example, Song Kaijie and Wan Hongjing, Preparation of polystyrene microspheres modified by carboxylation on microparticle surface and shear thickening properties of their polyethylene glycol suspension, Polymer Materials Science and Engineering, 2018, 34(05):170-176.

[0003] Emulsion polymerization can also be used to prepare carboxylated polymer microspheres, such as the one-step preparation of uniformly sized styrene-methacrylic acid microspheres using a combination of emulsion polymerization and microwave-assisted polymerization. For example, Zhou Tianyu et al., Microwave-assisted preparation of styrene-methacrylic acid microspheres for the separation and enrichment of triazine herbicides in rice, Journal of Jilin Normal University (Natural Science Edition), 2021, 42(03):87-94. This process requires the use of surfactants, and the pre-mixed reaction solution needs to be transferred to a high-pressure microwave jar for polymer preparation. The preparation of carboxyl-containing polymer microspheres using traditional emulsion polymerization methods requires control of the amount and method of adding emulsifiers and functional monomers, and involves multiple steps. Zhao Ruijian, Preparation of Nanoscale Carboxyl Polymer Microspheres by Emulsion Polymerization, New Chemical Materials, 2010, 38(01): 95-98. Surface carboxylated polymer microspheres can be prepared by dispersion polymerization and soap-free emulsion polymerization combined with subsequent chemical reactions. For example, by using dispersion polymerization and soap-free emulsion polymerization, followed by saponification and hydrolysis, monodisperse functionalized polymethyl methacrylate microspheres with different carboxyl contents can be prepared. Chen Biyun et al., Preparation and Characterization of Carboxyl Functionalized Polymethyl Methacrylate Microspheres, New Chemical Materials, 2013, 41(08): 92-94. This process can control the carboxyl content on the surface of the microspheres, requires two steps, and the process takes a long time. Dispersion polymerization combined with seed modification method can further synthesize carboxyl polystyrene microspheres. Qin Xue, Monodisperse Preparation and Characterization of Carboxyl Polystyrene Microspheres, Guangdong Chemical Industry, 2011, 38(11): 12-13. This is a two-step process that requires an electrodispersant. Precipitation polymerization can also be used to prepare carboxyl-functionalized microspheres. For example, a two-step precipitation polymerization method is used to graft a shell with low crosslinking degree and carboxyl functional groups onto the surface of the core, resulting in monodisperse or narrowly dispersed micron-sized core-shell microspheres. (Jiang Xuhong, Preparation of core-shell microspheres with carboxyl groups on the surface by two-step precipitation polymerization, Polymer Materials Science and Engineering, 2012, 28(07): 132-135.) This method requires acetonitrile organic solvent and a two-step preparation process.

[0004] Traditional process preparation methods involve stirred tank reactions, which are batch reactions with relatively long reaction cycles, and some processes are quite cumbersome. Stirred tank reactions are not conducive to heat and mass transfer, making process scale-up difficult and product quality control challenging. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of long reaction cycles, cumbersome processes, and poor heat and mass transfer in batch reactions, which are common in existing technologies. Furthermore, the process is difficult to scale up, and product quality is often difficult to control, leading to uneven particle size. This invention provides a method and system for preparing carboxylated acrylate-styrene copolymer microspheres, as well as the carboxylated acrylate-styrene copolymer microspheres obtained by this method and their applications. This preparation method is simple and continuous, allows for easy adjustment of material addition ratios, and does not require the addition of any stabilizers or surfactants. The resulting polymer microspheres have clean surfaces and narrow particle size distribution.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing carboxylated acrylate-styrene copolymer microspheres, characterized in that the method comprises:

[0007] S1. Mix the first mixture and the second mixture evenly to obtain the raw material liquid;

[0008] S2. The raw material liquid and the initiator are mixed evenly to obtain a reaction liquid. The reaction liquid is subjected to a polymerization reaction in a tubular reactor to obtain carboxylated acrylate-styrene copolymer microspheres.

[0009] The first mixture contains styrene, acrylate, and a first dispersion medium; the second mixture contains a carboxyl functional monomer and a second dispersion medium.

[0010] Both the first dispersion medium and the second dispersion medium are water.

[0011] The second aspect of the present invention provides carboxylated acrylate-styrene copolymer microspheres prepared by the preparation method described in the first aspect of the present invention.

[0012] The third aspect of the present invention provides an application of the carboxylated acrylate-styrene copolymer microspheres described in the second aspect of the present invention as a redispersible adhesive powder.

[0013] The fourth aspect of the present invention provides a system for preparing carboxylated acrylate-styrene copolymer microspheres as described in the second aspect of the present invention, characterized in that the system comprises: a first raw material tank (1-1), a second raw material tank (1-2), a third raw material tank (1-3), a first mixer (2-1), a second mixer (2-2), a tubular reactor (3), and a heater (4);

[0014] The first raw material tank (1-1) contains a first mixture, and the second raw material tank (1-2) contains a second mixture;

[0015] The first raw material tank (1-1) and the second raw material tank (1-2) are respectively connected to the inlet of the first mixer (2-1) to feed the first mixture and the second mixture into the first mixer (2-1) to obtain the raw material liquid;

[0016] The third raw material tank (1-3) contains an initiator;

[0017] The third raw material tank (1-3) is connected to the inlet of the second mixer (2-2) and is used to feed the initiator into the first mixer (2-1);

[0018] The outlet of the first mixer (2-1) is connected to the inlet of the second mixer (2-2) for feeding the raw material liquid into the second mixer (2-2) and mixing it with the initiator to obtain a reaction solution;

[0019] The inlet of the tubular reactor (3) is connected to the outlet of the second mixer (2-2), and a heater (4) is provided on the outside of the tubular reactor (3) for polymerizing the reaction liquid to obtain the carboxylated acrylate-styrene copolymer microspheres.

[0020] Through the above technical solutions, the carboxylated acrylate-styrene copolymer microspheres and their preparation method, system and application provided by the present invention have the following beneficial effects: the method is simple to operate, the process is continuous, it is convenient to adjust the addition ratio of materials, and no stabilizers or surfactants are added during the preparation process, resulting in polymer microspheres with clean surfaces and narrow particle size distribution. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the carboxylated acrylate-styrene copolymer microspheres prepared in Example 1 of this invention;

[0022] Figure 2 This is a schematic diagram of the system for preparing carboxylated acrylate-styrene copolymer microspheres in Example 1 of the present invention.

[0023] Explanation of reference numerals in the attached figures

[0024] 1-1 First raw material tank; 1-2 Second raw material tank; 1-3 Third raw material tank; 2-1 First mixer; 2-2 Second mixer; 3 Tubular reactor; 4 Heater; 5-1 First chromatography pump; 5-2 Second chromatography pump; 5-3 Third chromatography pump; 6-1 First check valve; 6-2 Second check valve; 6-3 Third check valve; 6-4 Fourth check valve; 6-5 Fifth check valve; 7 Collection tank. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] The first aspect of this invention provides a method for preparing carboxylated acrylate-styrene copolymer microspheres, characterized in that the method comprises:

[0027] S1. Mix the first mixture and the second mixture evenly to obtain the raw material liquid;

[0028] S2. The raw material liquid and the initiator are mixed evenly to obtain a reaction liquid. The reaction liquid is subjected to a polymerization reaction in a tubular reactor to obtain carboxylated acrylate-styrene copolymer microspheres.

[0029] The first mixture contains styrene, acrylate, and a first dispersion medium; the second mixture contains a carboxyl functional monomer and a second dispersion medium.

[0030] Both the first dispersion medium and the second dispersion medium are water.

[0031] In this invention, the dispersion medium is water, which is immiscible with the reactant monomer raw materials. This reduces the viscosity of the reactant raw materials, provides a reaction site, removes the heat of reaction, and allows the resulting polymer to form a colloidal dispersion system. Furthermore, mixing styrene and acrylate before mixing with the carboxyl functional monomer allows for more uniform mixing of the reactant raw materials and facilitates adjustment of the proportion of structural units in the synthesized polymer.

[0032] According to the present invention, the mass concentration of styrene in the first mixture is 5-25%, preferably 5-22.5%.

[0033] According to the present invention, the mass concentration of the acrylate in the first mixture is 5-15%, preferably 6-14%.

[0034] According to the present invention, the acrylate has the structure shown in formula (1).

[0035]

[0036] Wherein, R1 is H or a C1-C6 alkyl group, and R2 is a C1-C6 alkyl group.

[0037] Preferably, R1 is H or methyl, and R2 is a C1-C3 alkyl group.

[0038] According to the present invention, the carboxyl functional monomer has the structure shown in formula (2).

[0039]

[0040] R3 is H or a C1-C6 alkyl group.

[0041] According to a particularly preferred embodiment of the present invention, the carboxyl functional monomer is selected from methacrylic acid and acrylic acid.

[0042] In this invention, the carboxyl functional monomer is selected from methacrylic acid and acrylic acid, which enables the prepared copolymer microspheres to have good uniformity and a narrower particle size distribution coefficient.

[0043] According to the present invention, the carboxyl functional monomer is selected from methacrylic acid and acrylic acid, wherein the methacrylic acid in the second mixture accounts for 70%-95% of the total mass of the carboxyl functional monomer.

[0044] Furthermore, the methacrylic acid in the second mixture constitutes 70-90% of the total mass of the carboxyl functional monomers.

[0045] According to the present invention, the mass concentration of the carboxyl functional monomer in the second mixture is 10-40%, preferably 11-30%.

[0046] According to the present invention, the initiator is an aqueous solution of persulfate, preferably an aqueous solution of ammonium persulfate and / or an aqueous solution of potassium persulfate.

[0047] According to the present invention, the mass concentration of persulfate in the persulfate aqueous solution is 1-20%.

[0048] In this invention, the mass concentration of the persulfate meets the above-mentioned range, which can provide a suitable reaction rate.

[0049] Furthermore, in the persulfate aqueous solution, the mass concentration of the persulfate is 1-15%.

[0050] According to the present invention, the inner diameter of the tubular reactor is 0.1-2 mm.

[0051] In this invention, the inner diameter of the tubular reactor is within the range described above, which facilitates the removal of reaction heat during the reaction process and improves the uniformity of the polymer microspheres.

[0052] Furthermore, the inner diameter of the tubular reactor is 0.1-1.5 mm.

[0053] According to the present invention, the length of the tubular reactor is 200-10000 mm.

[0054] In this invention, the length of the tubular reactor meets the above-mentioned range, which can ensure the smooth progress of the reaction and guarantee a suitable conversion rate.

[0055] Furthermore, the length of the tubular reactor is 500-10000 mm.

[0056] According to the present invention, in step S1, the first mixture and the second mixture are mixed in a first mixer to obtain a raw material liquid.

[0057] In this invention, the first mixer is a T-type mixer, which ensures thorough and uniform mixing of the reaction raw materials, further improving the particle size distribution coefficient of the prepared polymer microspheres.

[0058] According to the present invention, the delivery rate of the first mixture is 1-15 ml / min.

[0059] According to the present invention, the delivery rate of the second mixture is 0.1-3 ml / min.

[0060] According to the present invention, the delivery rates of the first mixture and the second mixture respectively meet the above-mentioned ranges, which can better control the structure of the polymer obtained from the reaction and ensure the formation of a dispersion system.

[0061] According to the present invention, in step S2, the raw material liquid and the initiator are mixed in a second mixer to obtain a reaction solution.

[0062] In this invention, the second mixer is a T-type mixer, which can ensure that the reactants are mixed evenly.

[0063] According to the present invention, the delivery rate of the raw material liquid is 1.1-18 ml / min, preferably 1.1-15 ml / min.

[0064] According to the present invention, the delivery rate of the initiator is 1-15 ml / min, preferably 1-10 ml / min.

[0065] According to the present invention, the conditions for the polymerization reaction include: a reaction temperature of 65-95°C, preferably 65-90°C; and a reaction time of 2-24 h, preferably 6-18 h.

[0066] The second aspect of the present invention provides carboxylated acrylate-styrene copolymer microspheres prepared by the preparation method described in the first aspect of the present invention.

[0067] According to the present invention, the molar content of the structural units provided by styrene in the copolymer microspheres is 30-60%.

[0068] According to the present invention, the molar content of the structural units provided by acrylate in the copolymer microspheres is 20-55%.

[0069] According to the present invention, the molar content of structural units provided by carboxyl functional monomers in the copolymer microspheres is 10-30%.

[0070] In this invention, when the molar content of the structural units provided by styrene, the molar content of the structural units provided by acrylate, and the molar content of the structural units provided by carboxyl functional monomers in the copolymer microspheres each meet the above-mentioned ranges, the prepared copolymer microspheres have uniform particle size, excellent morphology, clean surface, and can be used as redispersible adhesive powder.

[0071] Furthermore, according to the present invention, the molar content of the structural units provided by styrene in the copolymer microspheres is 35-54%.

[0072] According to the present invention, the molar content of the structural units provided by acrylate in the copolymer microspheres is 26-45%.

[0073] According to the present invention, the molar content of structural units provided by carboxyl functional monomers in the copolymer microspheres is 17-23%.

[0074] In this invention, the sum of the molar content of structural units provided by styrene, the molar content of structural units provided by acrylate, and the molar content of structural units provided by carboxyl functional monomers in the copolymer microspheres is 100%.

[0075] According to a particularly preferred embodiment of the present invention, the carboxyl functional monomer is selected from methacrylic acid and acrylic acid. In the copolymer microspheres, the molar content of the structural units provided by methacrylic acid is 1-20%, the molar content of the structural units provided by acrylic acid is 1-20%, and the total content of the structural units provided by the carboxyl functional monomer is 10-30%.

[0076] According to the present invention, the average particle size of the copolymer microspheres is 200-1200 nm, preferably 200-900 nm.

[0077] According to the present invention, the weight-average particle size of the copolymer microspheres is 200-1400 nm, preferably 200-1200 nm.

[0078] According to the present invention, the particle size distribution coefficient of the copolymer microspheres is 1.002-1.02, preferably 1.005-1.02.

[0079] The third aspect of the present invention provides an application of the carboxylated acrylate-styrene copolymer microspheres described in the second aspect of the present invention as a redispersible adhesive powder.

[0080] In this invention, when the carboxylated acrylate-styrene copolymer microspheres are used as redispersible adhesive powder, their residual amount is not higher than 0.23 wt%, preferably not higher than 0.17 wt%.

[0081] The fourth aspect of the present invention provides a system for preparing carboxylated acrylate-styrene copolymer microspheres as described in the second aspect of the present invention, characterized in that the system comprises: a first raw material tank (1-1), a second raw material tank (1-2), a third raw material tank (1-3), a first mixer (2-1), a second mixer (2-2), a tubular reactor (3), and a heater (4);

[0082] The first raw material tank (1-1) contains a first mixture, and the second raw material tank (1-2) contains a second mixture;

[0083] The first raw material tank (1-1) and the second raw material tank (1-2) are respectively connected to the inlet of the first mixer (2-1) to feed the first mixture and the second mixture into the first mixer (2-1) to obtain the raw material liquid;

[0084] The third raw material tank (1-3) contains an initiator;

[0085] The third raw material tank (1-3) is connected to the inlet of the second mixer (2-2) and is used to feed the initiator into the first mixer (2-2);

[0086] The outlet of the first mixer (2-1) is connected to the inlet of the second mixer (2-2) for feeding the raw material liquid into the second mixer (2-2) and mixing it with the initiator to obtain a reaction solution;

[0087] The inlet of the tubular reactor (3) is connected to the outlet of the second mixer (2-2), and a heater (4) is provided on the outside of the tubular reactor (3) for polymerizing the reaction liquid to obtain the carboxylated acrylate-styrene copolymer microspheres.

[0088] In this invention, a stirring device is provided in the first raw material tank (1-1) for stirring and mixing the raw materials therein evenly.

[0089] In this invention, there are no particular limitations on the stirring conditions, as long as the raw materials can be mixed evenly, for example, the stirring speed can be 50-300 rpm.

[0090] In this invention, there are no particular limitations on the type of heater or the heating method, as long as it can provide the temperature required for the polymerization reaction. For example, it can be an oil bath or a water bath, with a temperature control range of 10-220℃ and a temperature control accuracy of ±1℃.

[0091] According to the present invention, the system further includes a pump (5), a one-way valve (6), and a collection tank (7);

[0092] The inlet of the collection tank (7) is connected to the outlet of the tubular reactor (3) for collecting the carboxylated acrylate-styrene copolymer microspheres.

[0093] In this invention, there are no special requirements for the type of pump; for example, it can be a chromatography pump.

[0094] In this invention, there are no special requirements for the operating conditions of the pump, as long as the liquid delivery rate specified in this invention can be met. For example, the maximum operating pressure of the pump is 2.5 MPa, and the flow rate range of the chromatography pump is 0.05-50 ml / min.

[0095] Combination Figure 2 The method and system described in this invention will be further explained below:

[0096] S1. Styrene, methacrylate and water are placed in the first raw material tank (1-1) and mixed evenly at a speed of 50-300 rpm to obtain a first mixture, wherein the mass concentration of styrene in the first mixture is 5-25% and the mass concentration of methyl methacrylate is 5-15%.

[0097] The carboxyl functional monomer and water are mixed evenly in the second raw material tank (1-2) to obtain the second mixture;

[0098] The first raw material tank (1-1) is connected to the inlet of the first mixer (2-1) via the first chromatography pump (5-1) and the first one-way valve (6-1), and the second raw material tank (1-2) is connected to the inlet of the first mixer (2-1) via the second chromatography pump (5-2) and the second one-way valve (6-2), respectively, to transport the first mixture and the second mixture to the first mixer (2-1) to obtain the raw material liquid;

[0099] S2. The third raw material tank (1-3) contains an initiator. The third raw material tank (1-3) is connected to the inlet of the second mixer (2-2) via the third chromatographic pump (5-3) and the third one-way valve (6-3) to deliver the initiator to the first mixer (2-2). The initiator is an aqueous solution of persulfate, and the mass concentration of the persulfate is 1-20%.

[0100] The outlet of the first mixer (2-1) is connected to the inlet of the second mixer (2-2) via a fourth one-way valve (6-4) to transport the raw material liquid to the second mixer (2-2) and mix it with the initiator in the first mixer (2-2) to obtain a reaction solution;

[0101] S3. The inlet of the tubular reactor (3) is connected to the outlet of the second mixer (2-2) through a fifth one-way valve (6-5), and a heater (4) is provided outside the tubular reactor (3). The reaction liquid undergoes a polymerization reaction in the tubular reactor to obtain carboxylated acrylate-styrene copolymer microspheres. The conditions of the polymerization reaction include: a reaction temperature of 65-95℃ and a reaction time of 2-24h.

[0102] S4. The inlet of the collection tank (7) is connected to the outlet of the tubular reactor (3) for collecting the carboxylated acrylate-styrene copolymer microspheres.

[0103] The tubular reactor has an inner diameter of 0.1-2 mm and a length of 200-10000 mm.

[0104] The delivery rate of the first mixture is 1-15 ml / min, and the delivery rate of the second mixture is 0.1-3 ml / min;

[0105] The delivery rate of the raw material liquid is 1.1-18 ml / min, and the delivery rate of the initiator is 1-15 ml / min.

[0106] The present invention will be described in detail below through embodiments. In the following embodiments,

[0107] The morphology of the polymer was observed using a Hitachi S-4800 scanning electron microscope.

[0108] The particle size of the polymer was measured using scanning electron microscopy graphics software;

[0109] The content of each structural unit in the polymer was tested using 1H NMR. The test method was to calculate the content of each structural unit by measuring the proportion of the peak area corresponding to the characteristic hydrogen in the corresponding structural unit in 1H NMR.

[0110] Number average particle size is Where n is the number of particles, and di is the particle size of the i-th particle;

[0111] Weight average particle size is Where n is the number of particles, and di is the particle size of the i-th particle;

[0112] The particle size distribution coefficient is P = Dw / Dn.

[0113] The raw materials used in the examples and comparative examples are all commercially available products commonly used in the art.

[0114] Example 1

[0115] S1. Styrene, methyl methacrylate and water are placed in the first raw material tank (1-1) and mixed evenly at a speed of 250 rpm to obtain a first mixture, wherein the mass concentration of styrene in the first mixture is 10% and the mass concentration of methyl methacrylate is 10%.

[0116] Methacrylic acid, acrylic acid, and water are mixed evenly in a second raw material tank (1-2) to obtain a second mixture. In the second mixture, methacrylic acid accounts for 85% of the total mass of carboxyl functional monomers, acrylic acid accounts for 15% of the carboxyl functional monomers, and the mass concentration of carboxyl functional monomers is 20%.

[0117] The first raw material tank (1-1) is connected to the inlet of the first mixer (2-1) via the first chromatography pump (5-1) and the first one-way valve (6-1), and the second raw material tank (1-2) is connected to the inlet of the first mixer (2-1) via the second chromatography pump (5-2) and the second one-way valve (6-2), respectively, to transport the first mixture and the second mixture to the first mixer (2-1) to obtain the raw material liquid;

[0118] S2. The third raw material tank (1-3) contains an initiator. The third raw material tank (1-3) is connected to the inlet of the second mixer (2-2) via the third chromatographic pump (5-3) and the third one-way valve (6-3) to deliver the initiator to the first mixer (2-2). The initiator is an aqueous solution of potassium persulfate with a mass concentration of 15%.

[0119] The outlet of the first mixer (2-1) is connected to the inlet of the second mixer (2-2) via a fourth one-way valve (6-4) to transport the raw material liquid to the second mixer (2-2) and mix it with the initiator in the first mixer (2-2) to obtain a reaction solution;

[0120] S3. The inlet of the tubular reactor (3) is connected to the outlet of the second mixer (2-2) through a fifth one-way valve (6-5), and a heater (4) is provided outside the tubular reactor (3). The reaction liquid undergoes a polymerization reaction in the tubular reactor to obtain carboxylated acrylate-styrene copolymer microspheres A1. The conditions of the polymerization reaction include: a reaction temperature of 90°C and a reaction time of 3.3 h.

[0121] S4. The inlet of the collection tank (7) is connected to the outlet of the tubular reactor (3) for collecting the carboxylated acrylate-styrene copolymer microspheres A1.

[0122] The tubular reactor has an inner diameter of 0.5 mm and a length of 10,000 mm.

[0123] The delivery rate of the first mixture is 8 ml / min, and the delivery rate of the second mixture is 2 ml / min;

[0124] The feed liquid is delivered at a rate of 10 ml / min, and the initiator is delivered at a rate of 5 ml / min.

[0125] The morphology of polymer microsphere A1 product is as follows: Figure 1 As shown. From Figure 1 It is evident that the obtained polymer microspheres A1 are monodisperse microspheres with smooth surfaces and uniform particle size. Analysis revealed that the carboxylated acrylate-styrene copolymer microspheres A1 are copolymer microspheres of styrene-methyl methacrylate-methacrylic acid, with the following molar content: 39% of the structural units provided by styrene, 41% by methyl methacrylate, 16% by methacrylic acid, and 4% by acrylic acid.

[0126] The obtained polymer microspheres A1 have a particle size of 530 nm, a particle size dispersion coefficient of 1.006, a number-average particle size of 530 nm, and a weight-average particle size of 533 nm.

[0127] Example 2

[0128] The method is carried out according to Example 1, with the following difference:

[0129] In the first mixture, the mass concentration of styrene is 15%, and the mass concentration of methyl methacrylate is 12%.

[0130] In the second mixture, methacrylic acid accounts for 80% of the total mass of carboxyl functional monomers, and acrylic acid accounts for 20% of the total mass of carboxyl functional monomers; the mass concentration of carboxyl functional monomers is 27%.

[0131] In the aqueous solution of potassium persulfate as the initiator, the mass concentration of potassium persulfate is 12.5%.

[0132] The polymerization reaction temperature is 85℃;

[0133] The tubular reactor has an inner diameter of 0.1 mm and a length of 8000 mm.

[0134] The delivery rate of the first mixture is 1 ml / min, and the delivery rate of the second mixture is 0.2 ml / min;

[0135] The feed liquid is delivered at a rate of 1.2 ml / min, and the initiator is delivered at a rate of 1 ml / min.

[0136] The obtained polymer microspheres A2 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of copolymer microspheres A2 are shown in Table 1 and Table 1 (continued).

[0137] Example 3

[0138] The method is carried out according to Example 1, with the following difference:

[0139] In the first mixture, the mass concentration of styrene is 8%, and the mass concentration of methyl methacrylate is 9%.

[0140] In the second mixture, methacrylic acid accounts for 75% of the total mass of carboxyl functional monomers, and acrylic acid accounts for 25% of the total mass of carboxyl functional monomers; the mass concentration of carboxyl functional monomers is 17%.

[0141] In the aqueous solution of potassium persulfate as the initiator, the mass concentration of potassium persulfate is 17.5%.

[0142] The tubular reactor has an inner diameter of 1 mm and a length of 3000 mm.

[0143] The delivery rate of the first mixture is 7 ml / min, and the delivery rate of the second mixture is 2 ml / min;

[0144] The delivery rate of the raw material liquid is 9 ml / min, and the delivery rate of the initiator is 7 ml / min;

[0145] The obtained polymer microspheres A3 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of copolymer microspheres A3 are shown in Table 1 and Table 1 (continued).

[0146] Example 4

[0147] The method is carried out according to Example 1, with the following difference:

[0148] In the first mixture, the mass concentration of styrene is 5%, and the mass concentration of methyl methacrylate is 6%.

[0149] In the second mixture, methacrylic acid accounts for 70% of the total mass of carboxyl functional monomers, and acrylic acid accounts for 30% of the total mass of carboxyl functional monomers; the mass concentration of carboxyl functional monomers is 11%.

[0150] In the aqueous solution of the initiator ammonium persulfate, the mass concentration of ammonium persulfate is 20%;

[0151] The tubular reactor has an inner diameter of 1.5 mm and a length of 2000 mm.

[0152] The delivery rate of the first mixture is 8.2 ml / min, and the delivery rate of the second mixture is 1.8 ml / min;

[0153] The delivery rate of the raw material liquid is 10 ml / min, and the delivery rate of the initiator is 10 ml / min;

[0154] The obtained polymer microspheres A4 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of copolymer microspheres A4 are shown in Table 1 and Table 1 (continued).

[0155] Example 5

[0156] The method is carried out according to Example 1, with the following difference:

[0157] In the first mixture, the mass concentration of styrene is 20%, and the mass concentration of methyl methacrylate is 10%.

[0158] In the second mixture, methacrylic acid accounts for 70% of the total mass of carboxyl functional monomers, and acrylic acid accounts for 30% of the total mass of carboxyl functional monomers; the mass concentration of carboxyl functional monomers is 30%.

[0159] In the aqueous solution of the initiator ammonium persulfate, the mass concentration of ammonium persulfate is 5%;

[0160] The polymerization reaction was carried out at a temperature of 75°C.

[0161] The tubular reactor has an inner diameter of 1.5 mm and a length of 3000 mm.

[0162] The delivery rate of the first mixture is 10 ml / min, and the delivery rate of the second mixture is 2.5 ml / min;

[0163] The feed liquid is delivered at a rate of 12.5 ml / min, and the initiator is delivered at a rate of 10 ml / min.

[0164] The obtained polymer microspheres A5 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of copolymer microspheres A5 are shown in Table 1 and Table 1 (continued).

[0165] Example 6

[0166] The method is carried out according to Example 1, with the following difference:

[0167] In the first mixture, the mass concentration of styrene is 20%, and the mass concentration of methyl methacrylate is 15%.

[0168] In the second mixture, methacrylic acid accounts for 90% of the total mass of carboxyl functional monomers, and acrylic acid accounts for 10% of the total mass of carboxyl functional monomers; the mass concentration of carboxyl functional monomers is 35%.

[0169] In the aqueous solution of the initiator ammonium persulfate, the mass concentration of ammonium persulfate is 2%;

[0170] The polymerization reaction was carried out at a temperature of 75°C.

[0171] The tubular reactor has an inner diameter of 2 mm and a length of 500 mm.

[0172] The delivery rate of the first mixture is 8 ml / min; the delivery rate of the second mixture is 1.5 ml / min.

[0173] The obtained polymer microspheres A6 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of copolymer microspheres A6 are shown in Table 1 and Table 1 (continued).

[0174] Example 7

[0175] The method is the same as in Example 1, except that the mass concentration of the methacrylate in the first mixture is 15%.

[0176] The obtained polymer microspheres A7 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of copolymer microspheres A7 are shown in Table 1 and Table 1 (continued).

[0177] Example 8

[0178] The method is the same as in Example 1, except that the delivery rate of the first mixture is 13 ml / min.

[0179] The obtained polymer microspheres A8 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of copolymer microspheres A8 are shown in Table 1 and Table 1 (continued).

[0180] Example 9

[0181] The method is the same as in Example 1, except that the inner diameter of the tubular reactor is 3 mm.

[0182] The obtained polymer microspheres A9 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of the copolymer microspheres A9 are shown in Table 1 and Table 1 (continued).

[0183] Example 10

[0184] The method is the same as in Example 1, except that the carboxyl functional monomer is only acrylic acid.

[0185] The obtained polymer microspheres A10 were tested, and the content of each structural unit, particle size, particle size dispersion coefficient, number-average particle size and weight-average particle size of the copolymer microspheres A10 are shown in Table 1 and Table 1 (continued).

[0186] Comparative Example 1

[0187] The method of Example 1 is different in that it does not contain carboxyl functional monomers. The first mixture and the initiator are directly mixed for polymerization. The reaction channel becomes blocked and polymer microspheres cannot be obtained.

[0188] Comparative Example 2

[0189] The method is the same as in Example 1, except that the first mixture, the second mixture, and the initiator are polymerized in a batch reactor to obtain copolymer microspheres D2.

[0190] The obtained polymer microspheres D2 were tested, and the content of each structural unit, particle size, particle size distribution coefficient, number-average particle size, and weight-average particle size of the copolymer microspheres D2 are shown in Table 1 and Table 1 (continued).

[0191] Comparative Example 3

[0192] The method of Example 1 was followed, except that both the first and second dispersion media were ethyl acetate. A polymer dispersion colloidal system was not obtained.

[0193] Table 1

[0194]

[0195]

[0196] As can be seen from the results in Table 1, the polymer microspheres prepared in Examples 1-10 of this invention have a narrow particle size distribution, and the particle size dispersion coefficient is not higher than 1.02. The polymer microspheres have uniform particle size.

[0197] Furthermore, embodiments 1-6 that satisfy the preferred embodiment of the present invention achieve significantly better technical effects, with microspheres A1-A6 having a narrower particle size distribution and a particle size dispersion coefficient not higher than 1.01.

[0198] To further illustrate that the polymer microspheres prepared in this invention can be used as redispersible polymer powder, 2g of the polymer microsphere dry powder prepared in the examples and comparative examples were dispersed in 100g of deionized water, stirred at 200 rpm for 10 minutes, filtered through a 38-micron pore size filter, and the residual polymer that did not pass through the filter was dried. The content R of the residual substance was tested, and its effect was also tested. The results are shown in Table 2.

[0199] The residual amount R is calculated as follows:

[0200]

[0201] Where w1 is the amount of residual polymer that did not pass through the filter paper, and w0 is the amount of the initially added polymer dry powder.

[0202] Table 2

[0203]

[0204]

[0205] As can be seen from the above description, the polymer microspheres prepared by this technology can be used as dispersible adhesive powder, with lower residual amount and better redispersibility than adhesive powder obtained by traditional methods.

[0206] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing carboxylated acrylate-styrene copolymer microspheres, characterized in that, The method includes: S1. Mix the first mixture and the second mixture evenly to obtain the raw material liquid; S2. The raw material liquid and the initiator are mixed evenly to obtain a reaction liquid. The reaction liquid is subjected to a polymerization reaction in a tubular reactor to obtain carboxylated acrylate-styrene copolymer microspheres. The first mixture contains styrene, acrylate, and a first dispersion medium; the second mixture contains a carboxyl functional monomer and a second dispersion medium. Both the first dispersion medium and the second dispersion medium are water; The carboxyl functional monomer is selected from methacrylic acid and acrylic acid; The initiator is an aqueous solution of persulfate.

2. The preparation method according to claim 1, wherein, In the first mixture, the mass concentration of styrene is 5-25%; And / or, in the first mixture, the mass concentration of the acrylate is 5-15%; And / or, the acrylate has the structure shown in formula (1). Equation (1); Wherein, R1 is H or a C1-C6 alkyl group, and R2 is a C1-C6 alkyl group; And / or, the methacrylic acid in the second mixture is 70%-95% of the total mass of the carboxyl functional monomers; And / or, the mass concentration of the carboxyl functional monomer in the second mixture is 10-40%.

3. The preparation method according to claim 2, wherein, In the first mixture, the mass concentration of styrene is 5-22.5%; And / or, in the first mixture, the mass concentration of the acrylate is 6-14%; And / or, R1 is H or methyl, and R2 is a C1-C3 alkyl group; And / or, the methacrylic acid in the second mixture is 70-90% of the total mass of the carboxyl functional monomers; And / or, the mass concentration of the carboxyl functional monomer in the second mixture is 11-30%.

4. The preparation method according to any one of claims 1-3, wherein, The initiator is an aqueous solution of ammonium persulfate and / or an aqueous solution of potassium persulfate; And / or, in the aqueous solution of the persulfate, the mass concentration of the persulfate is 1-20%.

5. The preparation method according to any one of claims 1-3, wherein, The inner diameter of the tubular reactor is 0.1-2 mm; And / or, the length of the tubular reactor is 200-10000 mm.

6. The preparation method according to claim 5, wherein, The inner diameter of the tubular reactor is 0.1-1.5 mm; And / or, the length of the tubular reactor is 500-10000 mm.

7. The preparation method according to any one of claims 1-3, wherein, In step S1, the first mixture and the second mixture are mixed in a first mixer to obtain a raw material liquid.

8. The preparation method according to claim 7, wherein, The delivery rate of the first mixture is 1-15 ml / min; And / or, the delivery rate of the second mixture is 0.1-3 ml / min.

9. The preparation method according to claim 8, wherein, The delivery rate of the first mixture is 1-12.5 ml / min; And / or, the delivery rate of the second mixture is 0.1-2.5 ml / min.

10. The preparation method according to any one of claims 1-3, wherein, In step S2, the raw material liquid and the initiator are mixed in a second mixer to obtain a reaction solution.

11. The preparation method according to claim 10, wherein, The delivery rate of the raw material liquid is 1.1-18 ml / min; And / or, the initiator is delivered at a rate of 1-15 ml / min.

12. The preparation method according to claim 11, wherein, The delivery rate of the raw material liquid is 1.1-15 ml / min; And / or, the initiator is delivered at a rate of 1-10 ml / min.

13. The preparation method according to any one of claims 1-3, wherein, The conditions for the polymerization reaction include: a reaction temperature of 65-95℃ and a reaction time of 2-24h.

14. The preparation method according to claim 13, wherein, The conditions for the polymerization reaction include: a reaction temperature of 65-90℃ and a reaction time of 3-18h.

15. A carboxylated acrylate-styrene copolymer microsphere prepared by the preparation method according to any one of claims 1-14.

16. The carboxylated acrylate-styrene copolymer microspheres according to claim 15, wherein, In the copolymer microspheres, the molar content of structural units provided by styrene is 30-60%; And / or, in the copolymer microspheres, the molar content of structural units provided by acrylate is 20-55%; And / or, in the copolymer microspheres, the molar content of structural units provided by carboxyl functional monomers is 10-30%.

17. The carboxylated acrylate-styrene copolymer microspheres according to claim 16, wherein, In the copolymer microspheres, the molar content of structural units provided by styrene is 35-54%; And / or, in the copolymer microspheres, the molar content of structural units provided by acrylate is 26-45%; And / or, in the copolymer microspheres, the molar content of structural units provided by carboxyl functional monomers is 17-23%.

18. The carboxylated acrylate-styrene copolymer microspheres according to any one of claims 15-17, wherein, The number-average particle size of the copolymer microspheres is 200-1200 nm; And / or, the weight-average particle size of the copolymer microspheres is 200-1400 nm; And / or, the particle size distribution coefficient of the copolymer microspheres is 1.002-1.

02.

19. The carboxylated acrylate-styrene copolymer microspheres according to claim 18, wherein, The number-average particle size of the copolymer microspheres is 200-900 nm; And / or, the weight-average particle size of the copolymer microspheres is 200-1200 nm; And / or, the particle size distribution coefficient of the copolymer microspheres is 1.005-1.

02.

20. The use of the carboxylated acrylate-styrene copolymer microspheres according to any one of claims 15-19 as a redispersible adhesive powder.

21. A system for preparing carboxylated acrylate-styrene copolymer microspheres according to any one of claims 15-19, characterized in that, The system includes: a first raw material tank 1-1, a second raw material tank 1-2, a third raw material tank 1-3, a first mixer 2-1, a second mixer 2-2, a tubular reactor 3, and a heater 4; The first raw material tank 1-1 contains a first mixture, and the second raw material tank 1-2 contains a second mixture; The first raw material tank 1-1 and the second raw material tank 1-2 are respectively connected to the inlet of the first mixer 2-1, and are used to send the first mixture and the second mixture into the first mixer 2-1 to obtain the raw material liquid; The third raw material tank 1-3 contains an initiator; The third raw material tank 1-3 is connected to the inlet of the second mixer 2-2 and is used to feed the initiator into the first mixer 2-1; The outlet of the first mixer 2-1 is connected to the inlet of the second mixer 2-2, which is used to feed the raw material liquid into the second mixer 2-2 and mix it with the initiator to obtain a reaction solution; The inlet of the tubular reactor 3 is connected to the outlet of the second mixer 2-2, and a heater 4 is provided on the outside of the tubular reactor 3 for polymerizing the reaction liquid to obtain the carboxylated acrylate-styrene copolymer microspheres.

22. The system according to claim 21, wherein, The system also includes a pump 5, a one-way valve 6, and a collection tank 7; The inlet of the collection tank 7 is connected to the outlet of the tubular reactor 3, and is used to collect the carboxylated acrylate-styrene copolymer microspheres.

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