Surfactant for steel slag derived calcium carbonate and preparation method thereof

Abstract

The invention discloses a surfactant for steel slag derived calcium carbonate and a preparation method of the surfactant, and relates to the field of surfactants. The surfactant comprises fatty acid salt and polyether modified polyvinyl phenol in a mass ratio of (3-6): (4-7), the polyether modified polyvinyl phenol is prepared by the following steps: firstly, taking vinyl phenol as a comonomer, and carrying out free radical copolymerization reaction in an inert atmosphere to prepare a vinyl phenol polymer with the molecular weight of 1000-10000; and carrying out ring-opening polymerization on the vinyl phenol polymer and ethylene oxide gas in the presence of a catalyst. The molar ratio of the vinyl phenol to the ethylene oxide is 1: (5-15). The surfactant provided by the invention can effectively solve the problems that high-oil-absorption-value steel slag derived calcium carbonate is poor in stability and easy to agglomerate and precipitate in a water-based system.

Description

Technical Field

[0001] The present application relates to the field of surfactants, and in particular to a surfactant for steel slag-derived calcium carbonate and a preparation method thereof. Background Art

[0002] Precipitated calcium carbonate is an important industrial filler due to its excellent whitening properties,

[0003] Due to its reinforcing and low-cost properties, it is widely used in coatings, plastics, rubber, papermaking and other fields. Traditional calcium carbonate production relies on limestone calcination, which not only consumes a large amount of mineral resources but also is accompanied by significant carbon emissions and environmental damage. In recent years, the technology of using calcium sources from industrial solid waste such as steel slag to produce precipitated calcium carbonate through carbonization reactions has attracted much attention. This technology can not only realize the resource utilization of solid waste, but also reduce greenhouse gas emissions through carbon capture, with significant dual environmental and economic benefits.

[0004] However, the complex composition of steel slag and the poor matching between the calcium source release rate and carbonization conditions make it difficult to precisely control the nucleation and growth process of the generated calcium carbonate crystals. Problems such as wide crystal size distribution and irregular morphology are common. The uneven distribution of surface energy of crystals with large particle size differences, coupled with the influence of impurity ions such as iron and magnesium remaining in the steel slag, makes the oil absorption value of the product significantly higher than that of traditional calcium carbonate (usually 40 to 80 mL / 100 g). When this type of calcium carbonate is used in water-based coatings or adhesives, particles are prone to agglomeration, and conventional dispersants have difficulty forming a stable adsorption layer on the crystal surface. Stratification and sedimentation often occur during storage, seriously restricting its application.

[0005] Although attempts have been made in the prior art to improve dispersibility by adding polycarboxylate or phosphate dispersants, their molecular structures are not sufficiently compatible with the high specific surface area and multiple active site characteristics of steel slag calcium carbonate, and they are unable to effectively inhibit crystal reagglomeration in the long term. Excessive addition can easily lead to an abnormal increase in the viscosity of the system, affecting the coating performance. Summary of the Invention

[0006] In order to solve the problem that steel slag-derived calcium carbonate is difficult to maintain stability and easily agglomerates and precipitates during long-term storage in an aqueous system, the present application provides a surfactant for steel slag-derived calcium carbonate and a preparation method thereof.

[0007] In a first aspect, the present application provides a surfactant for steel slag-derived calcium carbonate, comprising:

[0008] Fatty acid salt and polyether-modified polyvinyl phenol in a mass ratio of 3-6:4-7;

[0009] The polyether-modified polyvinylphenol is first prepared by subjecting vinylphenol as a comonomer to a free radical copolymerization reaction in an inert atmosphere to obtain a vinylphenol polymer with a molecular weight of 1,000 to 10,000; the vinylphenol polymer is then subjected to ring-opening polymerization with ethylene oxide gas in the presence of a catalyst to obtain the polyether-modified polyvinylphenol; the molar ratio of the vinylphenol to the ethylene oxide is 1:5 to 15.

[0010] The structural formula of the polyether-modified polyvinylphenol described in this application is as follows:

[0011]

[0012] Where R is -(CH2CH2O) m H, m = 5 ~ 15.

[0013] In any of the above technical solutions, the catalyst is tin tetrachloride.

[0014] In any of the above technical solutions, the amount of the catalyst is 1.0 to 2.0 wt% of the vinyl phenol.

[0015] In any of the above technical solutions, the temperature of the ring-opening polymerization is 80-100° C., and the pressure is 0.05-0.1 MPa.

[0016] It is worth noting that ethylene oxide is prone to self-polymerization or decomposition at temperatures above 100°C, which is not conducive to chain growth control.

[0017] In any of the above technical solutions, the molecular weight of the vinylphenol polymer is 2000-5000.

[0018] Vinylphenol polymers with a molecular weight of 1,000 to 10,000 are suitable for calcium carbonate dispersion. When the molecular weight is below 1,000, the polymer chain is too short, resulting in insufficient anchoring points and prone to desorption. Above 10,000, the molecular chain becomes too rigid, making it difficult to adapt to the particle surface morphology, resulting in a decrease in adsorption capacity. A molecular weight range of 2,000 to 5,000 provides the polymer with moderate flexibility and excellent adsorption.

[0019] It is worth noting that the molecular weight of the vinylphenol polymer of the present application can be measured by gel permeation chromatography and viscosity method.

[0020] In any of the above technical solutions, the vinylphenol polymer is pretreated before the ring-opening polymerization, specifically, the polymer is vacuum dehydrated to a moisture content of less than 1%.

[0021] The polyether-modified polyvinylphenol in this application has a backbone vinylphenol unit that exhibits excellent affinity for steel slag-derived calcium carbonate, a material with high oil absorption. The sidechain polyether segments, through hydration, form a three-dimensional barrier on the particle surface. This steric hindrance significantly reduces particle agglomeration and effectively disperses the steel slag-derived calcium carbonate particles. The synergistic effect of fatty acid salts and polyether chains further enhances the stability of the adsorption layer. The fatty acid salts preferentially adsorb to high-surface energy sites, while the polyether chains cover low-energy regions. This complementary coating improves the surface energy uniformity of particles of varying sizes.

[0022] In any technical solution, the fatty acid salt is selected from sodium stearate, potassium stearate, sodium oleate, sodium laurate or ammonium stearate.

[0023] In any of the above technical solutions, the raw materials for the free radical copolymerization reaction further include olefin sulfonate, and the amount of the olefin sulfonate is 2 to 5 wt% of the vinyl phenol.

[0024] In any of the above technical solutions, the olefin sulfonate is selected from one or more of sodium vinyl sulfonate, sodium styrene sulfonate, sodium methacrylate sulfonate, and sodium allyl sulfonate.

[0025] In any of the above technical solutions, the method for preparing the vinylphenol polymer is as follows: vinylphenol and an olefin sulfonate are dissolved in a solvent, heated to 65-75°C under a nitrogen atmosphere, an initiator solution is added dropwise, the reaction time is 2-4 hours, and hydroquinone is added to terminate the reaction; the solution is added dropwise into cold methanol for precipitation, filtered, and vacuum dried to obtain the product.

[0026] In any of the above technical solutions, the amount of the initiator used is 2-5% of the mass of the comonomer.

[0027] In any of the above technical solutions, the amount of hydroquinone used is 0.1 to 0.3% of the mass of vinyl phenol.

[0028] The introduction of olefin-containing sulfonates increases the negative charge density on the particle surface due to the strong ionization properties of the sulfonic acid groups, enhancing electrostatic repulsion and significantly improving the stability of the dispersion. Furthermore, the sulfonic acid groups form an amphiphilic structure with the polyether chains. At low temperatures, the hydrophilicity of the sulfonic acid groups dominates, allowing the polymer to fully stretch. As the temperature rises, the dehydration contraction of the polyether chains is offset by the hydration of the sulfonic acid groups. This improved temperature responsiveness allows the dispersant to maintain a stable adsorption conformation over a temperature range of 5 to 80°C.

[0029] In a second aspect, the present application provides a method for preparing a surfactant for steel slag-derived calcium carbonate, which comprises: mixing polyether-modified polyvinyl phenol and fatty acid salt according to the ratio of any of the above-mentioned surfactants, and stirring them evenly.

[0030] In summary, this application has the following beneficial effects:

[0031] This application utilizes the synergistic effect of fatty acid salts and polyether-modified polyvinylphenol to form a multi-layered dispersion system. The fatty acid salts rapidly adsorb and reduce surface energy differences, while the polymer grafted with polyether chains inhibits aggregation through a steric barrier. The introduction of sulfonic acid groups imparts both electrostatic stability and temperature adaptability to the dispersion, raising its cloud point. DETAILED DESCRIPTION

[0032] Example

[0033] Example 1: A surfactant for steel slag-derived calcium carbonate: 40 g of ammonium stearate and 60 g of polyether-modified polyvinyl phenol were mixed and stirred at 50° C. for 2 hours to obtain a uniform paste.

[0034] Polyether-modified polyvinylphenol is prepared according to the following steps:

[0035] Preparation of vinylphenol polymers

[0036] 500 g of vinylphenol and 15 g of sodium styrenesulfonate were dissolved in 600 mL of tetrahydrofuran and replaced with nitrogen three times to remove dissolved oxygen.

[0037] The temperature was raised to 70°C, and a solution of 15g of azobisisobutyronitrile in 50mL of ethanol was added dropwise at a rate of 10mL / min. The reaction was allowed to continue at this temperature for 3 hours. 1.25g of hydroquinone was added to terminate the reaction, and the mixture was cooled to room temperature. The reaction solution was slowly added dropwise to 4L of cold methanol for precipitation. After filtration, the mixture was washed three times with methanol and dried under vacuum at 60°C for 12 hours to obtain a vinylphenol polymer with an average molecular weight of approximately 3600.

[0038] Preparation of polyether-modified polyvinylphenol

[0039] The dried vinylphenol polymer was placed in an autoclave and vacuum-dehydrated at 100°C to a moisture content of 0.8%. 7.5g of tin tetrachloride was added, and ethylene oxide gas was introduced at a molar ratio of 1:10 (vinylphenol:ethylene oxide). The reaction was maintained at 95°C under a pressure of 0.08 MPa for 8 hours. After the reaction was complete, the reaction was cooled to 50°C and the pressure was released to obtain polyether-modified polyvinylphenol (m=10).

[0040] Example 2, a surfactant for steel slag-derived calcium carbonate, 30g of sodium oleate and 70g of polyether-modified polyvinyl phenol were mixed and stirred at 60°C for 1 hour to obtain a uniform paste.

[0041] Polyether-modified polyvinylphenol is prepared according to the following steps:

[0042] Preparation of vinylphenol polymers

[0043] 300 g of vinylphenol and 6 g of sodium vinyl sulfonate were dissolved in 400 mL of toluene and replaced with nitrogen three times to remove dissolved oxygen.

[0044] Raise the temperature to 65°C and add a solution of 6g of benzoyl peroxide in 30mL of acetone dropwise at a rate of 10mL / min. Keep the reaction constant for 4 hours. Add 0.9g of hydroquinone to terminate the reaction, then cool to room temperature. The reaction solution is slowly dripped into 4L of cold methanol for precipitation. Filter, wash three times with methanol, and dry under vacuum at 60°C for 12 hours to obtain a vinylphenol polymer with an average molecular weight of approximately 2000.

[0045] Preparation of polyether-modified polyvinylphenol

[0046] The dried vinylphenol polymer was placed in an autoclave and vacuum-dehydrated at 105°C to a moisture content of 0.5%. 6g of tin tetrachloride was added, and ethylene oxide gas was introduced at a molar ratio of 1:15 (vinylphenol:ethylene oxide). The reaction was maintained at 100°C at a pressure of 0.05 MPa for 6 hours. After the reaction was complete, the mixture was cooled to 50°C and the pressure was released to obtain polyether-modified polyvinylphenol (m=15).

[0047] Example 3, a surfactant for steel slag-derived calcium carbonate, 60g of sodium stearate and 40g of polyether-modified polyvinyl phenol were mixed and stirred at 40°C for 2 hours to obtain a uniform paste.

[0048] Polyether-modified polyvinylphenol is prepared according to the following steps:

[0049] Preparation of vinylphenol polymers

[0050] 700 g of vinylphenol and 35 g of sodium styrenesulfonate were dissolved in 800 mL of tetrahydrofuran and replaced with nitrogen three times to remove dissolved oxygen.

[0051] Raise the temperature to 75°C and add a solution of 30g of azobisisobutyronitrile in 70mL of ethanol dropwise at a rate of 5mL / min. Keep the reaction constant for 2 hours. Add 0.8g of hydroquinone to terminate the reaction, then cool to room temperature. Slowly add the reaction solution dropwise to 5L of cold methanol for precipitation. Filter, wash with methanol three times, and dry under vacuum at 60°C for 12 hours to obtain a vinylphenol polymer with an average molecular weight of approximately 5000.

[0052] Preparation of polyether-modified polyvinylphenol

[0053] The dried vinylphenol polymer was placed in an autoclave and vacuum-dehydrated at 100°C to a moisture content of 0.9%. 7.0g of tin tetrachloride was added, and ethylene oxide gas was introduced at a molar ratio of 1:5 (vinylphenol:ethylene oxide). The reaction was maintained at 82°C under a pressure of 0.1 MPa for 10 hours. After the reaction was complete, the reaction was cooled to 50°C and the pressure was released to obtain polyether-modified polyvinylphenol (m=5).

[0054] Example 4, a surfactant for steel slag-derived calcium carbonate, differs from Example 1 in that sodium styrene sulfonate is replaced by an equal mass of vinyl phenol.

[0055] Example 5, a surfactant for steel slag-derived calcium carbonate, 40g of ammonium stearate and 60g of polyether-modified polyvinyl phenol were mixed and stirred at 50°C for 2 hours to obtain a uniform paste.

[0056] Polyether-modified polyvinylphenol is prepared according to the following steps:

[0057] Preparation of vinylphenol polymers

[0058] 500 g of vinylphenol and 15 g of sodium styrenesulfonate were dissolved in 600 mL of tetrahydrofuran and replaced with nitrogen three times to remove dissolved oxygen.

[0059] Raise the temperature to 75°C and add a solution of 25g of azobisisobutyronitrile in 50mL of ethanol dropwise at a rate of 15mL / min. Keep the reaction constant for 2 hours. Add 1.25g of hydroquinone to terminate the reaction, then cool to room temperature. Slowly add the reaction solution dropwise to 4L of cold methanol for precipitation. Filter, wash with methanol three times, and dry under vacuum at 60°C for 12 hours to obtain a vinylphenol polymer with an average molecular weight of approximately 1200.

[0060] The preparation of polyether-modified polyvinylphenol is the same as in Example 1.

[0061] Example 6, a surfactant for steel slag-derived calcium carbonate, 40g of ammonium stearate and 60g of polyether-modified polyvinyl phenol were mixed and stirred at 50°C for 2 hours to obtain a uniform paste.

[0062] Polyether-modified polyvinylphenol is prepared according to the following steps:

[0063] Preparation of vinylphenol polymers

[0064] 500 g of vinylphenol and 15 g of sodium styrenesulfonate were dissolved in 600 mL of tetrahydrofuran and replaced with nitrogen three times to remove dissolved oxygen.

[0065] The temperature was raised to 65°C, and a solution of 10 g of azobisisobutyronitrile in 50 mL of ethanol was added dropwise at a rate of 5 mL / min. The reaction was allowed to continue at this constant temperature for 4 hours. The reaction was terminated by adding 1.25 g of hydroquinone, and the mixture was cooled to room temperature. The reaction solution was slowly added dropwise to 4 L of cold methanol for precipitation. After filtration, the mixture was washed three times with methanol and dried under vacuum at 60°C for 12 hours to obtain a vinylphenol polymer with an average molecular weight of approximately 9600.

[0066] The preparation of polyether-modified polyvinylphenol is the same as in Example 1.

[0067] Comparative Example

[0068] Comparative Example 1, a surfactant for steel slag-derived calcium carbonate, differs from Example 1 in that ammonium stearate is replaced by an equal mass of polyether-modified polyvinyl phenol.

[0069] Comparative Example 2, a surfactant for steel slag-derived calcium carbonate, differs from Example 1 in that the polyether-modified polyvinyl phenol is replaced by an equal mass of ammonium stearate.

[0070] Comparative Example 3, a surfactant for steel slag-derived calcium carbonate, differs from Example 1 in that the polyether-modified polyvinyl phenol is replaced by an isomeric alcohol polyether surfactant (Pluronic PE6100) of equal mass.

[0071] Comparative Example 4, a surfactant for steel slag-derived calcium carbonate, differs from Example 1 in that polyether-modified polyvinyl phenol and ammonium stearate are replaced by equal amounts of sodium polycarboxylate (DP5040).

[0072] Performance testing

[0073] Test 1: Surfactant stability test

[0074] Sample Preparation: Ten samples of the same specifications (D50 particle size 2 μm, oil absorption 60 mL / 100 g) were prepared. The samples, slag-derived calcium carbonate, and water were mixed thoroughly with a surfactant. Polyvinyl alcohol (PVA1788) was then added and stirred at 500 rpm for 1 hour to prepare the samples. The mass ratio of surfactant, slag-derived calcium carbonate, polyvinyl alcohol, and water was 5:20:10:65.

[0075] Test method: (1) The particle size and particle size distribution of the sample were tested using a Malvern laser particle size analyzer to obtain the initial average particle size and particle size distribution uniformity (PDI). The average particle size was then measured after the sample was placed at room temperature (23 ± 2 °C) for 3 months.

[0076] (2) The sample was placed in a constant temperature environment of 5°C for 1 month and then its average particle size was measured.

[0077] (3) The sample was placed in a constant temperature environment of 80°C for 1 month and then its average particle size was measured.

[0078] Table 1. Stability test results

[0079]

[0080] From Examples 1 to 6 and Comparative Examples 1 to 4 and Table 1, it can be seen that the polyether-modified polyvinyl phenol and fatty acid salt used in the present application can effectively promote the dispersion of steel slag-derived calcium carbonate and inhibit its agglomeration and sedimentation. It can maintain good storage stability for a long time in the temperature range of 5-80°C without obvious agglomeration and sedimentation.

[0081] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A surfactant for steel slag-derived calcium carbonate, characterized in that: include: Fatty acid salt and polyether-modified polyvinyl phenol in a mass ratio of 3-6:4-7; The polyether-modified polyvinylphenol is first prepared by subjecting vinylphenol as a comonomer to a free radical copolymerization reaction in an inert atmosphere to obtain a vinylphenol polymer with a molecular weight of 1,000 to 10,000; the vinylphenol polymer is then subjected to ring-opening polymerization with ethylene oxide gas in the presence of a catalyst to obtain the polyether-modified polyvinylphenol; the molar ratio of the vinylphenol to the ethylene oxide is 1:5 to 15.

2. The surfactant according to claim 1, characterized in that The catalyst is tin tetrachloride.

3. The surfactant according to claim 2, characterized in that The amount of the catalyst used is 1.0-2.0 wt% of the vinyl phenol.

4. The surfactant according to claim 1, characterized in that The temperature of the ring-opening polymerization is 80-100° C., and the pressure is 0.05-0.1 MPa.

5. The surfactant according to claim 1, characterized in that The molecular weight of the vinylphenol polymer is 2000-5000.

6. The surfactant according to claim 1, characterized in that The raw materials for the free radical copolymerization reaction further include olefin sulfonate, and the amount of the olefin sulfonate is 2-5 wt% of the vinyl phenol.

7. The surfactant according to claim 6, characterized in that The olefin sulfonate is selected from one or more of sodium vinyl sulfonate, sodium styrene sulfonate, sodium methacrylate sulfonate, and sodium allyl sulfonate.

8. The surfactant according to claim 6, characterized in that The vinylphenol polymer preparation method comprises the following steps: dissolving vinylphenol and an olefin sulfonate in a solvent, heating the solvent to 65-75° C. under a nitrogen atmosphere, dripping an initiator solution, reacting for 2-4 hours, and then adding hydroquinone to terminate the reaction; dripping the solution into cold methanol for precipitation, filtering, and vacuum drying to obtain the polymer.

9. The surfactant according to claim 8, characterized in that The amount of the initiator used is 2-5% of the mass of the comonomer.

10. A method for preparing a surfactant for steel slag-derived calcium carbonate, characterized in that: include: The preparation method is obtained by mixing polyether-modified polyvinyl phenol and fatty acid salt according to the ratio of any one of the surfactants described in claims 1 to 9 and stirring them uniformly.

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