Nano material modified alcohol amine grinding aid as well as preparation method and application thereof

Abstract

The invention discloses a nano material modified alcohol amine grinding aid as well as a preparation method and application thereof, and the preparation method comprises the following steps: firstly, carrying out esterification reaction on alcohol amine and an acid small monomer containing double bonds to generate an esterification product; then, carrying out bulk polymerization on the esterification product and a silane coupling agent KH-570; and finally, combining the bulk polymerization product with the nano-material through a dehydration reaction of a silane coupling agent and hydroxyl on the surface of the nano-material to form the nano-material modified alcohol amine grinding aid. According to the invention, the nano material is directly grafted into the alcohol amine, so that the dispersity of the nano material in the cement grinding process can be effectively optimized, the friction force and energy consumption among cement particles can be reduced, the efficiency and stability of the cement production process can be improved, and the strength and durability of the cement product are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of cement grinding aids, and specifically relates to a nano material modified alcohol amine grinding aid and a preparation method and application thereof. Background Art

[0002] In the cement grinding process, the rational use of grinding aids can significantly increase the output by about 10% to 15%. However, grinding aids currently face many challenges in practical applications, including precipitation, strength degradation, and potential negative impacts on the environment. Precipitation reduces the effectiveness of grinding aids, and strength degradation affects the long-term performance of cement.

[0003] The grinding effect of grinding aids is closely related to the components and structure of the selected grinding aids and their interaction with cement particles. In order to solve the application problems of previous grinding aids, many researchers are committed to developing the structure of new grinding aids. Among them, in addition to the more studied chemically modified alcohol amines, nanomaterial grinding aids also show great potential.

[0004] For example, Chinese patent CN109180056A discloses a nano-scale molybdenum disulfide grinding aid and its preparation method, wherein the components and their mass percentages are: diethanol monoisopropanolamine 30-33%, triethanolamine 7-8%, molybdenum disulfide dispersion 7-8%, molasses 11-12%, polyol 11-12%, saturated salt water 25-30%, and the balance is water. Chinese patent CN115368052A discloses a nano-crystalline core-type early strength cement grinding aid and its preparation method, wherein the raw materials are: calcium salt: 3-20%; silicon salt: 4-20%; polyol: 0-20%; alcohol amine: 5-43%; dispersant: 1-10%; and the balance is water.

[0005] In the above patents, nanomaterials are only directly compounded with other raw materials, while the compounding of organic and inorganic materials is prone to precipitation and poor storage stability. It is also easy to make it difficult for nanomaterials to be evenly mixed into the entire cement system. This is because in the cement mill, due to the high temperature, the water in the grinding aid is easy to volatilize, which will cause the nanomaterials to easily agglomerate, making it difficult for the nanomaterials to be evenly mixed into the entire cement system, thereby affecting their uniform dispersion and long-term stability between cement particles. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a nanomaterial modified alcoholamine grinding aid and its preparation method and application. Directly grafting nanomaterials into alcoholamines can effectively optimize the dispersibility of nanomaterials in the cement grinding process, which can not only reduce the friction and energy consumption between cement particles, but also improve the efficiency and stability of the cement production process, thereby improving the strength and durability of cement products.

[0007] The technical solution adopted by the present invention is as follows:

[0008] The present invention provides a method for preparing a nano material modified alcohol amine grinding aid, the preparation method comprising the following steps:

[0009] (1) maintaining the temperature at 90-120° C., under the protection of inert gas, adding a catalyst to the alcohol amine, and then adding an acid monomer containing a double bond in multiple times, and stirring the reaction for at least 1 hour after the addition is completed;

[0010] (2) maintaining the temperature at 70-100° C., adding a catalyst and a chain transfer agent to the reaction solution obtained in step (1), and then dropping KH-570, adding more catalyst when the addition is halfway through, and continuing to stir the reaction for 10-30 minutes after the addition is complete;

[0011] (3) Dispersing the nanomaterial in a solvent, then adding the reaction solution obtained in step (2), adjusting the pH of the system to 4-6, stirring the reaction at 40-60° C. for 5-7 hours, and vacuum drying to obtain a nanomaterial-modified alcoholamine grinding aid.

[0012] In step (1), the alcoholamine is any one or more of monoethanolamine, diethanolamine, triethanolamine, triethylenepropanolamine, and diethanol monoisopropanolamine; or, the alcoholamine is replaced by glycerol.

[0013] In step (1), the catalyst is phenol.

[0014] In step (1), the acid monomer containing a double bond is any one or more of maleic anhydride, methacrylic acid, acrylic acid, and maleic acid; the acid monomer containing a double bond is added in five equal portions, each time with an interval of 30 minutes.

[0015] In step (1), the mass ratio of triethanolamine, catalyst and acid monomer containing double bonds is 1:0.005-0.01:0.5-5.0.

[0016] In step (1), the inert gas is nitrogen.

[0017] In step (2), the catalyst is ammonium persulfate, azobisisobutyl cyanide, or hydrogen peroxide; and the chain transfer agent is sodium hypophosphite.

[0018] In step (2), the mass ratio of the reaction solution obtained in step (1), the catalyst, the chain transfer agent, and KH-570 is 1: 0.01-0.05: 0.01-0.05: 0.1-0.5.

[0019] In step (3), the nano material is nano-SiO 2 、Nano-TiO 2 、Nano-CaCO3 , any one or more of nano-CSH.

[0020] In step (3), the mass ratio of the nanomaterial to the reaction solution obtained in step (2) is 1:10-100.

[0021] In step (3), the solvent is ethanol.

[0022] The invention also provides a nano material modified alcohol amine grinding aid prepared by the preparation method.

[0023] The present invention also provides the use of the nano material modified alcohol amine grinding aid as a cement grinding aid, wherein the nano material modified alcohol amine grinding aid helps to form a nano-scale lubricating layer between cement particles, promotes the dispersion and lubrication of particles, and thus improves the effect of cement grinding process. In addition, the uniformly dispersed nano material can also serve as a nucleation site to promote the uniform distribution of cement hydration products, and improve the early strength development and long-term performance stability of cement. The hydroxyl and carboxyl groups released by the modified alcohol amine during the cement hydration process form complexes with metal ions, accelerate the hydration rate of cement, and thus significantly improve the early and late strength and durability of cement.

[0024] In the preparation method of the nano-material modified alcoholamine grinding aid provided by the present invention, firstly, alcoholamine and a small acid monomer containing a double bond are subjected to an esterification reaction to generate an esterification product. Then, the esterification product is subjected to bulk polymerization with a silane coupling agent KH-570; finally, the bulk polymerization product is combined with the nano-material through a dehydration reaction between the silane coupling agent and the surface hydroxyl group of the nano-material to form a nano-material modified alcoholamine grinding aid. The present invention improves the combination mode of the grinding aid and the nano-material through a series of steps such as alcoholamine esterification, grafting of silane coupling agent and surface modification of nano-materials, and effectively solves the problem of the dispersibility of nano-materials in cement particles.

[0025] Taking the esterification reaction of triethanolamine and maleic anhydride in a molar ratio of 1:1 as an example, the nanomaterial is nano-SiO 2 The reaction occurring in the above preparation process is schematically shown as follows:

[0026]

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) Through the grafting of nanomaterials with modified alcohol amines, during the cement grinding process, the nanomaterials can be evenly distributed with the modified alcohol amines throughout the cement system, effectively solving the problems of nanomaterial agglomeration and easy precipitation of organic and inorganic materials in composite use. At the same time, nanomaterials can form a nano-scale lubricating layer between cement particles, effectively reducing the friction resistance between particles, thereby promoting the dispersion and lubrication of particles, which can not only reduce energy consumption in the cement production process, significantly improve grinding efficiency, but also extend the service life of grinding equipment. In addition, during the hydration process of cement, nanomaterials can regulate the morphology and size distribution of cement crystals, thereby affecting the early strength development of cement and the stability of long-term performance.

[0029] (2) After the silane coupling agent participates in the polymerization reaction, it can not only react with the hydroxyl groups on the surface of the nanomaterial to achieve a strong dispersion effect, but also hydrolyze in aqueous solution to produce hydroxyl groups. The increase in the number of hydroxyl groups is beneficial to improving the grinding aid effect of cement.

[0030] (3) Alcoholamine is connected to the molecular structure of modified alcoholamine through esterification, which not only plays a grinding aid role, but also can hydrolyze and continuously release hydroxyl and carboxyl groups under the strong alkaline conditions of cement solution. The released hydroxyl and carboxyl groups react with Ca in cement solution. 2+ 、Al 3+ The complexation of metal ions accelerates the C 3 A, C 3 The hydrolysis of minerals such as S accelerates the cement hydration rate and improves the strength of cement of the same age. By controlling the hydrolysis rate of the esterification product through the difficulty of hydrolysis, the rate of improvement of cement strength can be indirectly controlled, achieving the effect of improving both early and late strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the infrared spectrum of nano-silicon dioxide;

[0032] Figure 2 This is the infrared spectrum of the nanomaterial modified alcoholamine grinding aid prepared in Example 1. DETAILED DESCRIPTION

[0033] The present invention is described in detail below with reference to the embodiments.

[0034] Example 1

[0035] A method for preparing a nano material modified alcohol amine grinding aid comprises the following steps:

[0036] (1) Preparation of functional monomers

[0037] First, 74.50 g of triethanolamine was added to a 250 ml flask equipped with a magnet and a thermometer. The magnetic stirring speed was 500 r / min, the oil bath was heated to 90°C, and a circulating vacuum pump was used to evacuate the oil until no bubbles emerged. Under vacuum conditions, 0.5 g of phenol was added, and 49.00 g of maleic anhydride was added five times on average, each time with an interval of 30 minutes. The esterification lasted for 3 hours in total. The molar ratio of triethanolamine to maleic anhydride was 1:1. After the reaction, the mixture was cooled to room temperature to obtain a light yellow functional monomer maleic anhydride-triethanolamine.

[0038] (2) Preparation of synthetic products

[0039] Take 197.60g of functional monomer maleic anhydride-triethanolamine and add it to a 250ml three-necked flask, heat it to 80℃, add 2.5g of ammonium persulfate and 6g of sodium hypophosphite, then add 39.74g of KH-570 dropwise for 3h, add 1g of ammonium persulfate in the middle of 1.5h, keep warm for 1h after the addition is completed, and then cool to room temperature to obtain a light yellow synthetic product maleic anhydride-triethanolamine-KH-570.

[0040] (3) Preparation of nanomaterial-modified alcoholamine grinding aid

[0041] 2g nano-SiO 2 Add to 200g of ethanol, ultrasonically disperse for 1h under mechanical stirring, add 100g of the synthetic product maleic anhydride-triethanolamine-KH-570, adjust the pH to 4-6 with ammonia water, stir in a water bath at 50°C for 6h, and then vacuum dry at 90°C for 12h. The product after drying is a nanomaterial modified alcoholamine grinding aid.

[0042] The infrared spectrum of nano-silicon dioxide is as follows Figure 1 As shown in the figure, it can be seen that within the range of 1100cm-1, the Si-O absorption peak of nano-silicon dioxide appears, indicating that the structure contains nano-silicon dioxide.

[0043] The infrared spectrum of the nanomaterial modified alcohol amine grinding aid prepared in this embodiment is as follows: Figure 2As shown in the figure, it can be seen that in the range of 1100cm-1, the Si-O absorption peak also appeared, further confirming that the structure contains nano-silica. At 1600cm-1, the characteristic absorption peak of C=O (ester group) stretching vibration appeared, and the absorption peak of Si-O-C was shown at 1250cm-1, indicating that KH-570 is contained in the structure. The spectrum also shows the characteristic absorption peaks of acrylic acid at 1680cm-1 (C=O stretching vibration characteristic absorption peak) and 1410cm-1 (C-C bending vibration characteristic absorption peak), indicating that acrylic acid is contained in the structure. In the range of 3500cm-1, the peak of N-H stretching vibration appeared, and the absorption peak of C-H stretching vibration was shown in the range of 2800cm-1, proving that triethanolamine is contained in the structure. Therefore, through infrared spectroscopy analysis, it was successfully proved that silica was successfully grafted into the modified alcoholamine structure.

[0044] Example 2

[0045] The rest is the same as in Example 1, except that the nano-SiO 2 Replaced with an equal amount of nano-TiO 2 .

[0046] Example 3

[0047] The rest is the same as in Example 1, except that the nano-SiO 2 Replaced with an equal amount of nano-CaCO 3 .

[0048] Example 4

[0049] The rest is the same as Example 1, except that maleic anhydride is replaced by an equal amount of methacrylic acid.

[0050] Example 5

[0051] The rest is the same as in Example 1, except that 74.50 g of triethanolamine is replaced by 95.50 g of triisopropanolamine.

[0052] Example 6

[0053] The rest is the same as in Example 1, except that 2.5 g of ammonium persulfate in step (2) is replaced by 5 g of hydrogen peroxide.

[0054] Example 7

[0055] A method for preparing a nano material modified alcohol amine grinding aid comprises the following steps:

[0056] (1) Preparation of functional monomers

[0057] First, 74.50 g of triethanolamine was added to a 250 mL flask equipped with a magnet and a thermometer. The magnetic stirring speed was 500 r / min, the oil bath was heated to 100 ° C, and a circulating vacuum pump was used to evacuate until no bubbles emerged. Under vacuum conditions, 0.75 g of phenol was added, and 149.0 g of maleic anhydride was added in five times on average, with an interval of 30 minutes each time. The esterification lasted for a total of 3 hours. After the reaction, it was cooled to room temperature to obtain a light yellow functional monomer maleic anhydride-triethanolamine.

[0058] (2) Preparation of synthetic products

[0059] Take 197.60g of functional monomer maleic anhydride-triethanolamine and add it to a 250ml three-necked flask, heat it to 90℃, add 3.0g of ammonium persulfate and 9.9g of sodium hypophosphite, then add 79.0g of KH-570 dropwise for 3h, add 1g of ammonium persulfate in the middle of 1.5h, keep warm for 1h after the addition is completed, and then cool to room temperature to obtain a light yellow synthetic product maleic anhydride-triethanolamine-KH-570.

[0060] (3) Same as step (3) in Example 1.

[0061] Example 8

[0062] The rest is the same as in Example 1, except that step (3) is:

[0063] 2g nano-SiO 2 Add to 200g of ethanol, ultrasonically disperse for 1h under mechanical stirring, add 40g of the synthetic product maleic anhydride-triethanolamine-KH-570, adjust the pH to 4-6 with ammonia water, stir in a water bath at 50°C for 6h, and then vacuum dry at 90°C for 12h. The product after drying is a nanomaterial modified alcoholamine grinding aid.

[0064] Comparative Example 1

[0065] The rest is the same as in Example 1, except that step (2) is omitted. The specific preparation process is as follows:

[0066] (1) Preparation of functional monomers

[0067] First, 74.50 g of triethanolamine was added to a 250 ml flask equipped with a magnet and a thermometer. The magnetic stirring speed was 500 r / min, the oil bath was heated to 90°C, and a circulating vacuum pump was used to evacuate the oil until no bubbles emerged. Under vacuum conditions, 0.5 g of phenol was added, and 49.00 g of maleic anhydride was added five times on average, each time with an interval of 30 minutes. The esterification lasted for 3 hours in total. The molar ratio of triethanolamine to maleic anhydride was 1:1. After the reaction, the mixture was cooled to room temperature to obtain a light yellow functional monomer maleic anhydride-triethanolamine.

[0068] (2) Preparation of nanomaterial-modified alcoholamine grinding aid

[0069] 2g nano-SiO 2 Add to 200g ethanol, ultrasonically disperse for 1h under mechanical stirring, add 100g functional monomer maleic anhydride-triethanolamine, adjust the pH to 4-6 with ammonia water, stir in a water bath at 50℃ for 6h, and then vacuum dry at 90℃ for 12h. The product after drying is a nanomaterial modified alcoholamine grinding aid.

[0070] Comparative Example 2

[0071] The rest is the same as in Example 1, except that step (3) is omitted. The specific preparation process is as follows:

[0072] (1) Preparation of functional monomers

[0073] First, 74.50 g of triethanolamine was added to a 250 ml flask equipped with a magnet and a thermometer. The magnetic stirring speed was 500 r / min, the oil bath was heated to 90°C, and a circulating vacuum pump was used to evacuate the oil until no bubbles emerged. Under vacuum conditions, 0.5 g of phenol was added, and 49.00 g of maleic anhydride was added five times on average, each time with an interval of 30 minutes. The esterification lasted for 3 hours in total. The molar ratio of triethanolamine to maleic anhydride was 1:1. After the reaction, the mixture was cooled to room temperature to obtain a light yellow functional monomer maleic anhydride-triethanolamine.

[0074] (2) Preparation of synthetic products

[0075] Take 197.60g of functional monomer maleic anhydride-triethanolamine and add it to a 250ml three-necked flask, heat it to 80℃, add 2.5g of ammonium persulfate, 6g of sodium hypophosphite, and then drop 39.74g of KH-570 for 3h, and add 1g of ammonium persulfate in the middle of 1.5h. After the reaction, cool it to room temperature to obtain a light yellow synthetic product maleic anhydride-triethanolamine-KH-570.

[0076] Comparative Example 3

[0077] A method for preparing a grinding aid comprises the following steps:

[0078] 119.2g triethanolamine and 78.4g maleic anhydride were added to a 250ml three-necked flask, heated to 80°C, 2.5g ammonium persulfate and 6g sodium hypophosphite were added, and then 39.74g KH-570 was added dropwise for 3h, and 1g ammonium persulfate was added during the addition of 1.5h. After the reaction, the mixture was cooled to room temperature to obtain a light yellow synthetic product, maleic anhydride-triethanolamine-KH-570.

[0079] 2g nano-SiO 2Add to 200g of ethanol, disperse by ultrasonic under mechanical stirring for 1h, add 100g of the synthetic product maleic anhydride-triethanolamine-KH-570, adjust the pH to 4-6 with ammonia water, stir in a water bath at 50℃ for 6h, and vacuum dry at 90℃ for 12h.

[0080] Effect evaluation

[0081] 95% clinker and 5% desulfurized gypsum were mixed with blank (no grinding aid added), triethanolamine, triisopropanolamine, grinding aid samples obtained in Examples 1 to 6 and Comparative Examples 1 to 3, and then ground. The grinding aid dosage was 0.1% of the mass of cement clinker. After grinding for 30 minutes, the performance of the cement powder was tested. The results are shown in Table 1.

[0082] The specific surface area of ​​cement powder added with grinding aid is tested according to GB / T8074-2008 "Determination of specific surface area of ​​cement - Blaine method", the cement powder added with grinding aid is subjected to 45μm sieving test according to GB / T1345-2005 "Test method of cement fineness - sieve analysis method", and the strength of cement mortar is determined according to GB / T17671-2021 "Test method of cement mortar strength (ISO method)".

[0083] Table 1 Evaluation results of cement grinding aids

[0084]

[0085]

[0086] From the above content, it can be seen that the nanomaterial modified alcoholamine grinding aid provided by the present invention can significantly improve the 1d and 3d early strength of cement, and still improve the 28d strength to a certain extent; relative to the comparative example, the nanomaterial modified alcoholamine grinding aid prepared in Examples 1-6 has a better enhancement effect, and compared with triethanolamine and triethylene propanolamine, it takes into account both early strength and late strength.

[0087] The detailed description of a nanomaterial-modified alcoholamine grinding aid, its preparation method and application with reference to the above-mentioned embodiments is illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a nanomaterial-modified alcoholamine grinding aid, characterized in that: The preparation method comprises the following steps: (1) maintaining the temperature at 90-120° C., under the protection of inert gas, adding a catalyst to the alcohol amine, and then adding an acid monomer containing a double bond in multiple times, and stirring the reaction for at least 1 hour after the addition is completed; (2) maintaining the temperature at 70-100° C., adding a catalyst and a chain transfer agent to the reaction solution obtained in step (1), and then dropping KH-570, adding more catalyst when the addition is halfway through, and continuing to stir the reaction for 10-30 minutes after the addition is complete; (3) Dispersing the nanomaterial in a solvent, then adding the reaction solution obtained in step (2), adjusting the pH of the system to 4-6, stirring the reaction at 40-60° C. for 5-7 hours, and vacuum drying to obtain a nanomaterial-modified alcoholamine grinding aid.

2. The preparation method according to claim 1, characterized in that: In step (1), the alcoholamine is any one or more of monoethanolamine, diethanolamine, triethanolamine, triethylenepropanolamine, and diethanol monoisopropanolamine; or, the alcoholamine is replaced by glycerol.

3. The preparation method according to claim 1, characterized in that: In step (1), the catalyst is phenol.

4. The preparation method according to claim 1, characterized in that: In step (1), the acid monomer containing a double bond is any one or more of maleic anhydride, methacrylic acid, acrylic acid, and maleic acid; The acid monomer containing double bonds was added in five equal portions, with an interval of 30 minutes between each addition.

5. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of triethanolamine, catalyst and acid monomer containing double bonds is 1:0.005-0.01:0.5-5.

0.

6. The preparation method according to claim 1, characterized in that: In step (2), the catalyst is ammonium persulfate, azobisisobutyl cyanide, or hydrogen peroxide; and the chain transfer agent is sodium hypophosphite.

7. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the reaction solution obtained in step (1), the catalyst, the chain transfer agent, and KH-570 is 1: 0.01-0.05: 0.01-0.05: 0.1-0.

5.

8. The preparation method according to claim 1, characterized in that: In step (3), the nanomaterial is any one or more of nano-SiO2, nano-TiO2, nano-CaCO3, and nano-CSH.

9. The nanomaterial-modified alcoholamine grinding aid prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the nanomaterial modified alcoholamine grinding aid as claimed in claim 9 as a cement grinding aid.

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