Polymer-based dispersing agent as well as preparation process and application thereof

Abstract

The invention relates to the technical field of dispersing agents, and discloses a polymer-based dispersing agent and a preparation process and application thereof.The preparation method comprises the steps that polyethylene glycol and 5-nitroisophthalic acid react to obtain a dispersing agent precursor; the polymer-based dispersing agent contains a polyethylene glycol molecular chain, has good complexing and stabilizing effects on silver ions, plays a role of a dispersing agent, and is beneficial to inhibiting agglomeration of nano-silver and reducing the particle size. The polymer-based dispersing agent contains terminal hydroxyl reducing groups of polyethylene glycol, meanwhile, side chains of molecular chains contain a large number of reducing aniline groups, the effect of a reducing agent is achieved, reduction of silver ions can be effectively achieved at the low temperature, and the yield of nano-silver is remarkably increased.

Description

Technical Field

[0001] The present invention relates to the technical field of dispersants, and specifically relates to a polymer-based dispersant, a preparation process and an application thereof. Background Art

[0002] Dispersants are mainly applied in materials such as inorganic nanomaterials, pigments, ceramics, etc. The main ones include sodium hexametaphosphate, stearic acid, polyethylene glycol, polyacrylic acid, polyvinylpyrrolidone, etc. Among them, polymer dispersants have diverse functional groups, adjustable structures, strong stability, and can simultaneously have good water solubility and oil solubility and other properties, and are widely applied.

[0003] Nano silver is metallic silver in the form of nanoparticles, which has excellent electrical conductivity, thermal conductivity, bactericidal properties, etc., and has important applications in conductive adhesives, conductive inks, antibacterial materials, etc. When preparing nano silver, it is usually necessary to add dispersion stabilizers such as lauric acid, polyvinylpyrrolidone, polyvinyl alcohol, etc., as well as reducing agents such as glucose, sodium borohydride, sodium citrate, ethylene glycol, etc., which will lead to a more complex reaction system, reduce the yield of nano silver, and these reducing agents usually need to be at a relatively high temperature to achieve the reduction of silver ions. Chinese Patent with Publication No. CN105234426B discloses a preparation method of ultrafine nano silver, using polyvinyl alcohol or polyethylene glycol as a dispersant and ammonium formate as a reducing agent to prepare ultrafine silver particles, but the reaction temperature is too high, reaching 110 - 130 °C, and the particle size of the generated nano silver is relatively large. Summary of the Invention

[0004] (1) Technical problems solved by the present invention: Solved the problems of needing to add various raw materials such as dispersants and reducing agents when preparing nano silver, as well as the relatively high reaction temperature, and at the same time increased the yield of nano silver.

[0005] (2) Technical solution of the present invention: A polymer-based dispersant and a preparation process: (1) Add 100 parts by weight of 5-nitroisophthalic acid and 1.2 - 1.6 parts by weight of p-toluenesulfonic acid to 230 - 600 parts by weight of polyethylene glycol. After stirring and reacting, add the product to petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0006] (2) Add 100 parts by weight of the dispersant precursor and 85 - 140 parts by weight of sodium dithionite to an aqueous solution of inorganic base. After stirring and reacting, add saturated sodium chloride solution, stir, add dichloromethane, oscillate and extract, let it stand for layering, take the dichloromethane organic phase, add anhydrous sodium sulfate for drying and water removal, filter, and rotary evaporate the filtrate to obtain the polymer-based dispersant. The preparation reaction formula is:

[0007] Preferably, the temperature of the reaction in (1) is 180 - 200 °C, the reaction time is 10 - 18 h, and vacuum is drawn during the reaction.

[0008] Preferably, the molecular weight of polyethylene glycol is 400 - 800.

[0009] Preferably, the mass fraction of the inorganic base aqueous solution in (2) is 70 - 120 g / L.

[0010] Preferably, the inorganic base is sodium hydroxide or potassium hydroxide.

[0011] Preferably, the temperature of the reaction in (2) is 60 - 75 °C and the reaction time is 12 - 18 h.

[0012] Preferably, the polymer - based dispersant is applied to the preparation of silver nanoparticles. The preparation method of silver nanoparticles is as follows: Add 30 - 600 parts by weight of the polymer - based dispersant to deionized water, stir and then dropwise add an aqueous solution containing 1 part by weight of silver nitrate. Under dark conditions, stir and react at 30 - 60 °C for 18 - 24 h to obtain a silver nanoparticle sol; perform centrifugal separation, and wash the precipitate with deionized water and ethanol in sequence, and then dry to obtain silver nanoparticles.

[0013] (III) Beneficial technical effects of the present invention: Polyvinyl alcohol and 5 - nitroisophthalic acid are subjected to an esterification polymerization reaction, and then the nitro group is reduced by sodium dithionite to obtain a polymer - based dispersant containing aniline groups. It contains a polyethylene glycol molecular chain, has a good complexing and stabilizing effect on silver ions, functions as a dispersant, is beneficial to inhibiting the aggregation of silver nanoparticles, and reducing the particle size.

[0014] The polymer - based dispersant of the present invention contains the terminal hydroxyl reduction groups of polyethylene glycol, and at the same time, a large number of reducing aniline groups are contained in the side chain of the molecular chain, which functions as a reducing agent. It can effectively reduce silver ions at a low temperature of 30 - 60 °C, significantly increasing the yield of silver nanoparticles. Detailed Description of the Invention

[0015] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0016] Example 1:

[0017] (1) Add 420 g of polyethylene glycol 600, 100 g of 5 - nitroisophthalic acid, and 1.2 g of p - toluenesulfonic acid to a reaction kettle, draw vacuum and heat to 180 °C, stir and react for 18 h. Add the product to petroleum ether, stir and then filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0018] (2) Add 300 g of dispersant precursor and 370 g of sodium dithionite to 5 L of an aqueous sodium hydroxide solution with a mass fraction of 120 g / L, heat to 60 °C, stir and react for 18 h, add a saturated sodium chloride solution, stir, add dichloromethane, shake and extract, let stand for layer separation, take the dichloromethane organic phase, add anhydrous sodium sulfate for drying and water removal, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant.

[0019] (3) Add 30 g of the polymer-based dispersant to 400 mL of deionized water, stir, and dropwise add 300 mL of an aqueous solution containing 1 g of silver nitrate. Under light avoidance, stir and react at 30 °C for 24 h to obtain a silver nanoparticle sol; centrifuge and separate, wash the precipitate with deionized water and ethanol in sequence, dry to obtain silver nanoparticles, and weigh to obtain the yield.

[0020] Example 2:

[0021] (1) Add 230 g of polyethylene glycol 400, 100 g of 5-nitroisophthalic acid, and 1.3 g of p-toluenesulfonic acid to a reaction kettle, evacuate and heat to 190 °C, stir and react for 18 h, add the product to petroleum ether, stir and filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0022] (2) Add 300 g of the dispersant precursor and 420 g of sodium dithionite to 3 L of an aqueous sodium hydroxide solution with a mass fraction of 100 g / L, heat to 65 °C, stir and react for 18 h, add a saturated sodium chloride solution, stir, add dichloromethane, shake and extract, let stand for layer separation, take the dichloromethane organic phase, add anhydrous sodium sulfate for drying and water removal, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant.

[0023] (3) Add 150 g of the polymer-based dispersant to 1000 mL of deionized water, stir, and dropwise add 300 mL of an aqueous solution containing 1 g of silver nitrate. Under light avoidance, stir and react at 50 °C for 18 h to obtain a silver nanoparticle sol; centrifuge and separate, wash the precipitate with deionized water and ethanol in sequence, dry to obtain silver nanoparticles, and weigh to obtain the yield.

[0024] Example 3:

[0025] (1) Add 600 g of polyethylene glycol 800, 100 g of 5-nitroisophthalic acid, and 1.6 g of p-toluenesulfonic acid to a reaction kettle, evacuate and heat to 200 °C, stir and react for 10 h, add the product to petroleum ether, stir and filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0026] (2) Add 300 g of the dispersant precursor and 255 g of sodium dithionite to 3 L of an aqueous potassium hydroxide solution with a mass fraction of 70 g / L. Heat to 65 °C and stir for 18 h. Add a saturated sodium chloride solution, stir, add dichloromethane, shake for extraction, let it stand for layering, take the dichloromethane organic phase, add anhydrous sodium sulfate for drying and water removal, filter, and rotary evaporate the filtrate to obtain the polymer-based dispersant.

[0027] (3) Add 400 g of the polymer-based dispersant to 1500 mL of deionized water. Stir and then dropwise add 400 mL of an aqueous solution containing 1 g of silver nitrate. Stir and react at 60 °C for 12 h in the dark to obtain a silver nanosol; centrifuge and separate, wash the precipitate with deionized water and ethanol successively, dry to obtain silver nanoparticles, and weigh to obtain the yield.

[0028] Example 4:

[0029] (1) Add 230 g of polyethylene glycol 400, 100 g of 5-nitroisophthalic acid, and 1.2 g of p-toluenesulfonic acid to a reaction kettle. Evacuate and heat to 180 °C, stir and react for 18 h. Add the product to petroleum ether, stir and then filter, wash with petroleum ether, and dry to obtain the dispersant precursor.

[0030] (2) Add 300 g of the dispersant precursor and 420 g of sodium dithionite to 5 L of an aqueous sodium hydroxide solution with a mass fraction of 70 g / L. Heat to 75 °C and stir for 12 h. Add a saturated sodium chloride solution, stir, add dichloromethane, shake for extraction, let it stand for layering, take the dichloromethane organic phase, add anhydrous sodium sulfate for drying and water removal, filter, and rotary evaporate the filtrate to obtain the polymer-based dispersant.

[0031] (3) Add 600 g of the polymer-based dispersant to 2000 mL of deionized water. Stir and then dropwise add 400 mL of an aqueous solution containing 1 g of silver nitrate. Stir and react at 40 °C for 24 h in the dark to obtain a silver nanosol; centrifuge and separate, wash the precipitate with deionized water and ethanol successively, dry to obtain silver nanoparticles, and weigh to obtain the yield.

[0032] Comparative Example 1 (1) Add 30 g of polyethylene glycol 600 to 400 mL of deionized water. Stir and then dropwise add 300 mL of an aqueous solution containing 1 g of silver nitrate. Stir and react at 30 °C for 24 h in the dark to obtain a silver nanosolution; centrifuge and separate, wash the precipitate with deionized water and ethanol successively, dry to obtain silver nanoparticles, and weigh to obtain the yield.

[0033] Comparative Example 2 (1) Add 30 g of the dispersant precursor (prepared in Example 1) to 400 mL of deionized water. After stirring, add dropwise an aqueous solution containing 1 g of silver nitrate in 300 mL. Under dark conditions, stir and react at 30 °C for 24 h to obtain a silver nanosol. Centrifuge and separate, and wash the precipitate successively with deionized water and ethanol, then dry to obtain silver nanoparticles, and weigh them to obtain the yield.

[0034] Comparative Example 3 (1) Add 400 g of polyethylene glycol 600 to 1500 mL of deionized water. After stirring, add dropwise an aqueous solution containing 1 g of silver nitrate in 400 mL. Under dark conditions, stir and react at 60 °C for 12 h to obtain a silver nanosol. Centrifuge and separate, and wash the precipitate successively with deionized water and ethanol, then dry to obtain silver nanoparticles, and weigh them to obtain the yield.

[0035] Use a nano-particle size analyzer to measure the average particle size of silver nanoparticles in the sol.

[0036] Table 1 Silver Nanoparticle Yield and Particle Size Measurement Average particle size (nm) Yield (g) Example 1 8.6 0.165 Example 2 7.9 0.318 Example 3 13.4 0.473 Example 4 28.0 0.416 Comparative Example 1 6.8 0.057 Comparative Example 2 9.3 0.032 Comparative Example 3 12.1 0.267 After testing, when preparing silver nanoparticles in Examples 1 - 4, a polymer-based dispersant was added. The particle size of the prepared silver nanoparticles was only 7.9 - 28.0 nm, and the yield reached 0.165 - 0.473 g. This is mainly because the polymer-based dispersant contains polyethylene glycol molecular chains, which have good complexing and stabilizing effects on silver ions, acting as a dispersant, facilitating the inhibition of silver nanoparticle aggregation, reducing the particle size. At the same time, the polymer-based dispersant also contains terminal hydroxyl reduction groups of polyethylene glycol, and a large number of reducing aniline groups are contained in the side chains of the molecular chain, acting as a reducing agent. It can effectively reduce silver ions at a relatively low temperature (30 - 60 °C), significantly improving the yield of silver nanoparticles.

[0037] Compared with Example 1, in Comparative Example 1, polyethylene glycol was used as both a reducing agent and a dispersant, but the yield of the prepared silver nanoparticles was very low. This is mainly because at a relatively low temperature (30 °C), polyethylene glycol is difficult to effectively reduce silver ions to silver nanoparticles.

[0038] In Comparative Example 2, the dispersant precursor was used as both a dispersant and a reducing agent. It does not contain reducing aniline groups and is difficult to reduce silver ions at a relatively low temperature (30 °C), resulting in a very low yield of silver nanoparticles.

[0039] Compared with Comparative Example 1 and Example 3, in Comparative Example 3, polyethylene glycol was used as both a reducing agent and a dispersant to reduce silver ions at a high temperature (60 °C). The yield of silver nanoparticles was significantly higher than that in Comparative Example 1, but polyethylene glycol does not contain aniline groups, has fewer reduction sites, and is difficult to fully reduce silver ions, resulting in a yield lower than that in Example 3.

[0040] The above are only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A preparation process of a polymer-based dispersant, characterized in that, The preparation process: (1) Add 5-nitroisophthalic acid and p-toluenesulfonic acid to polyethylene glycol. After stirring and reacting, add the product to petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor; (2) Add the dispersant precursor and sodium dithionite to an aqueous solution of inorganic base. After stirring and reacting, add saturated sodium chloride solution, stir, add dichloromethane, oscillate for extraction, let it stand for layering, take the dichloromethane organic phase, add anhydrous sodium sulfate for drying and water removal, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant.

2. The preparation process of the polymer-based dispersant according to claim 1, wherein, In the step (1), the reaction temperature is 180 - 200 °C, the reaction time is 10 - 18 h, and vacuum is drawn during the reaction.

3. The preparation process of the polymer-based dispersant according to claim 1, characterized in that, In the step (1), the dosage of 5-nitroisophthalic acid is 100 parts by weight, the polyethylene glycol is 230 - 600 parts by weight, and the p-toluenesulfonic acid is 1.2 - 1.6 parts by weight.

4. The preparation process of the polymer-based dispersant according to claim 3, wherein, The molecular weight of the polyethylene glycol is 400 - 800.

5. The preparation process of the polymer-based dispersant according to claim 1, characterized in that, In the step (2), the mass fraction of the aqueous solution of inorganic base is 70 - 120 g / L.

6. The preparation process of the polymer-based dispersant according to claim 5, characterized in that, The inorganic base is sodium hydroxide or potassium hydroxide.

7. The preparation process of the polymer-based dispersant according to claim 1, characterized in that, In the step (2), the dosage of the dispersant precursor is 100 parts by weight, and the sodium dithionite is 85 - 140 parts by weight.

8. The preparation process of the polymer-based dispersant according to claim 1, characterized in that, In the step (2), the reaction temperature is 60 - 75 °C, and the reaction time is 12 - 18 h.

9. A polymer-based dispersant obtained by the preparation process according to any one of claims 1 - 8.

10. Use of the polymer-based dispersant as described in claim 9 in the preparation of nano silver, characterized in that, The preparation method of the nano silver is as follows: Add 30 - 600 parts by weight of the polymer-based dispersant to deionized water, stir, and then dropwise add an aqueous solution containing 1 part by weight of silver nitrate. Under light protection, stir and react at 30 - 60 °C for 18 - 24 h to obtain a nano silver sol; perform centrifugal separation, washing, and drying to obtain nano silver.

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