A polymer-based dispersant and its preparation process and application

Abstract

The present invention relates to the technical field of dispersants, and discloses a polymer-based dispersant and a preparation process and application. The present invention reacts polyethylene glycol and 5-nitroisophthalic acid to obtain a dispersant precursor; then reduces the nitro group through sodium dithionite to obtain a polymer-based dispersant, which contains polyethylene glycol molecular chains, has good complexing and stabilizing effects on silver ions, plays the role of a dispersant, is conducive to suppressing the agglomeration of nano silver, and reduces particle size. The polymer-based dispersant contains a terminal hydroxyl reducing group of polyethylene glycol, and the molecular chain side chain contains a large amount of reducing aniline groups, which plays the role of a reducing agent. It can effectively achieve the reduction of silver ions at low temperatures, significantly improving the output of nano silver.

Description

Technical Field

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

[0002] Dispersants are mainly used in inorganic nanomaterials, pigments, ceramics and other materials. They mainly include sodium hexametaphosphate, stearic acid, polyethylene glycol, polyacrylic acid, polyvinyl pyrrolidone, etc. Among them, polymer dispersants have diverse functional groups, adjustable structures, strong stability, and can have good water solubility and oil solubility at the same time. They are widely used.

[0003] Nanosilver is a nanometer-scale metallic silver element with excellent electrical conductivity, thermal conductivity, and bactericidal properties. It has important applications in conductive adhesives, conductive inks, antibacterial materials, etc. When preparing nanosilver, it is usually necessary to add dispersing stabilizers such as lauric acid, polyvinyl pyrrolidone, and polyvinyl alcohol, as well as reducing agents such as glucose, sodium borohydride, sodium citrate, and ethylene glycol. This makes the reaction system more complicated and reduces the yield of nanosilver. In addition, these reducing agents usually require higher temperatures to achieve the reduction of silver ions. The Chinese patent with announcement number CN105234426B discloses a method for preparing ultrafine nanosilver. Ultrafine silver particles are prepared using polyvinyl alcohol or polyethylene glycol as a dispersant and ammonium formate as a reducing agent. However, the reaction temperature is too high, reaching 110-130°C, and the resulting nanosilver has a large particle size. Summary of the Invention

[0004] (1) Technical problems solved by the present invention: The problems of needing to add multiple dispersants, reducing agents and other raw materials and high reaction temperature when preparing nanosilver are solved, while at the same time increasing the yield of nanosilver.

[0005] (II) Technical solution of the present invention: a polymer-based dispersant and its preparation process:

[0006] (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, stir to react, then add the product to petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0007] (2) Add 100 parts by weight of dispersant precursor and 85-140 parts by weight of sodium dithionite to an inorganic alkali aqueous solution, stir to react, then add saturated sodium chloride solution, stir, add dichloromethane, shake and extract, let stand to separate, take the dichloromethane organic phase, add anhydrous sodium sulfate to dry and remove water, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant. The preparation reaction formula is:

[0008]

[0009] Preferably, the reaction temperature in (1) is 180-200°C, the reaction time is 10-18 hours, and vacuum is applied during the reaction.

[0010] Preferably, the molecular weight of polyethylene glycol is 400-800.

[0011] Preferably, the mass fraction of the inorganic alkali aqueous solution in (2) is 70-120 g / L.

[0012] Preferably, the inorganic base is sodium hydroxide or potassium hydroxide.

[0013] Preferably, the reaction temperature in (2) is 60-75°C and the reaction time is 12-18 hours.

[0014] Preferably, the polymer-based dispersant is used to prepare nanosilver. The preparation method of nanosilver is as follows: 30-600 parts by weight of the polymer-based dispersant is added to deionized water, and after stirring, an aqueous solution containing 1 part by weight of silver nitrate is added dropwise. In the dark, the mixture is stirred at 30-60° C. for 18-24 hours to obtain a nanosilver sol; the mixture is centrifuged, and the precipitate is washed with deionized water and ethanol in sequence, and dried to obtain nanosilver.

[0015] (3) The beneficial technical effects of the present invention are as follows: polyvinyl alcohol and 5-nitroisophthalic acid are subjected to an esterification polymerization reaction, and the nitro group is then reduced with sodium dithionite to obtain a polymer-based dispersant containing an aniline group. The polymer-based dispersant contains polyethylene glycol molecular chains, has a good complexing and stabilizing effect on silver ions, acts as a dispersant, and is beneficial to inhibiting the agglomeration of nanosilver and reducing the particle size.

[0016] The polymer-based dispersant of the present invention contains terminal hydroxyl reducing groups of polyethylene glycol, and the molecular chain side chains contain a large number of reducing aniline groups, which act as a reducing agent and can effectively reduce silver ions at a low temperature of 30-60°C, thereby significantly improving the yield of nanosilver. DETAILED DESCRIPTION

[0017] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0018] Example 1:

[0019] (1) Add 420 g of polyethylene glycol 600, 100 g of 5-nitroisophthalic acid, and 1.2 g of p-toluenesulfonic acid into a reactor, evacuate the mixture, heat to 180 °C, and stir for 18 h. Add the product into petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0020] (2) Add 300 g of dispersant precursor and 370 g of sodium dithionite to 5 L of 120 g / L sodium hydroxide aqueous solution, heat to 60 ° C, stir and react for 18 h, add saturated sodium chloride solution, stir and add dichloromethane, shake and extract, let stand to separate, take the dichloromethane organic phase, add anhydrous sodium sulfate to dry and remove water, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant.

[0021] (3) Add 30 g of polymer-based dispersant 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 nanosilver sol; centrifuge and separate, wash the precipitate with deionized water and ethanol in sequence, and dry to obtain nanosilver, which is weighed to obtain the yield.

[0022] Example 2:

[0023] (1) Add 230 g of polyethylene glycol 400, 100 g of 5-nitroisophthalic acid, and 1.3 g of p-toluenesulfonic acid to a reactor, evacuate the reactor, heat to 190 °C, and stir for 18 h. Add the product to petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0024] (2) Add 300 g of dispersant precursor and 420 g of sodium dithionite to 3 L of 100 g / L sodium hydroxide aqueous solution, heat to 65 ° C, stir and react for 18 h, add saturated sodium chloride solution, stir and add dichloromethane, shake and extract, let stand to separate, take the dichloromethane organic phase, add anhydrous sodium sulfate to dry and remove water, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant.

[0025] (3) Add 150 g of a polymer-based dispersant to 1000 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 50 °C for 18 h in the dark to obtain a nanosilver sol. Centrifuge and separate. Wash the precipitate with deionized water and ethanol in sequence, dry, and obtain nanosilver. Weigh and obtain the yield.

[0026] Example 3:

[0027] (1) Add 600 g of polyethylene glycol 800, 100 g of 5-nitroisophthalic acid, and 1.6 g of p-toluenesulfonic acid into a reactor, evacuate the mixture, heat to 200 °C, and stir for 10 h. Add the product into petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0028] (2) Add 300 g of dispersant precursor and 255 g of sodium dithionite to 3 L of 70 g / L potassium hydroxide aqueous solution, heat to 65 ° C, stir and react for 18 h, add saturated sodium chloride solution, stir and then add dichloromethane, shake and extract, let stand to separate, take the dichloromethane organic phase, add anhydrous sodium sulfate to dry and remove water, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant.

[0029] (3) Add 400 g of a 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 nanosilver sol. Centrifuge and separate. Wash the precipitate with deionized water and ethanol in sequence, and dry to obtain nanosilver. The precipitate is weighed to obtain the yield.

[0030] Implementation:4:

[0031] (1) Add 230 g of polyethylene glycol 400, 100 g of 5-nitroisophthalic acid, and 1.2 g of p-toluenesulfonic acid into a reactor, evacuate the reactor, heat to 180 °C, and stir for 18 h. Add the product into petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor.

[0032] (2) Add 300 g of dispersant precursor and 420 g of sodium dithionite to 5 L of 70 g / L sodium hydroxide aqueous solution, heat to 75 ° C, stir and react for 12 h, add saturated sodium chloride solution, stir and add dichloromethane, shake and extract, let stand to separate, take the dichloromethane organic phase, add anhydrous sodium sulfate to dry and remove water, filter, and rotary evaporate the filtrate to obtain a polymer-based dispersant.

[0033] (3) Add 600 g of 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 nanosilver sol. Centrifuge and separate. Wash the precipitate with deionized water and ethanol in sequence, and dry to obtain nanosilver. The precipitate is weighed to obtain the yield.

[0034] Comparative Example 1

[0035] (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 nanosilver solution. Centrifuge and separate. Wash the precipitate with deionized water and ethanol in sequence, dry, and obtain nanosilver. The precipitate is weighed to obtain the yield.

[0036] Comparative Example 2

[0037] (1) 30 g of the dispersant precursor (prepared in Example 1) was added to 400 mL of deionized water. After stirring, 300 mL of an aqueous solution containing 1 g of silver nitrate was added dropwise. The mixture was stirred at 30° C. for 24 h in the dark to obtain a nanosilver sol. The precipitate was centrifuged and washed with deionized water and ethanol in sequence, and dried to obtain nanosilver. The precipitate was weighed to obtain the yield.

[0038] Comparative Example 3

[0039] (1) Add 400 g of polyethylene glycol 600 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 nanosilver sol. Centrifuge and separate. Wash the precipitate with deionized water and ethanol in sequence, and dry to obtain nanosilver. The precipitate is weighed to obtain the yield.

[0040] The average particle size of silver nanoparticles in the sol was measured using a nanoparticle size analyzer.

[0041] Table 1 Nanosilver production and particle size test

[0042] 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

[0043] Testing revealed that the addition of a polymer-based dispersant during the preparation of nanosilver in Examples 1-4 resulted in nanosilver particles with a particle size of only 7.9-28.0 nm and a yield of 0.165-0.473 g. This is primarily due to the presence of polyethylene glycol molecular chains in the polymer-based dispersant, which effectively complexes and stabilizes silver ions, acting as a dispersant and suppressing nanosilver aggregation, thereby reducing particle size. Furthermore, the polymer-based dispersant contains polyethylene glycol terminal hydroxyl reducing groups, and the molecular chain side chains contain a large number of reducing aniline groups, acting as a reducing agent. This allows for effective silver ion reduction at relatively low temperatures (30-60°C), significantly increasing nanosilver yield.

[0044] Compared with Example 1, Comparative Example 1 uses polyethylene glycol as a reducing agent and dispersant, but the yield of the prepared nanosilver is very low, mainly because at a relatively low temperature (30°C), polyethylene glycol is difficult to effectively reduce silver ions to nanosilver.

[0045] Comparative Example 2 uses a dispersant precursor as a dispersant and a reducing agent, which does not contain a reducing aniline group and is difficult to achieve reduction of silver ions at a relatively low temperature (30° C.), resulting in a very low yield of nanosilver.

[0046] Compared with Comparative Example 1 and Example 3, Comparative Example 3 uses polyethylene glycol as a reducing agent and dispersant to reduce silver ions at high temperature (60°C). The yield of nanosilver is significantly higher than that of Comparative Example 1. However, polyethylene glycol does not contain aniline groups and has fewer reduction sites, making it difficult to fully reduce silver ions, resulting in a lower yield than that of Example 3.

[0047] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A process for preparing a polymer-based dispersant, characterized in that: The preparation process: (1) Add 5-nitroisophthalic acid and p-toluenesulfonic acid to polyethylene glycol, stir to react, then add the product to petroleum ether, stir, filter, wash with petroleum ether, and dry to obtain a dispersant precursor; (2) Adding a dispersant precursor and sodium dithionite to an inorganic alkali aqueous solution, stirring the reaction, adding a saturated sodium chloride solution, stirring, adding dichloromethane, shaking extraction, standing to separate the layers, taking the dichloromethane organic phase, adding anhydrous sodium sulfate to dry and remove water, filtering, and rotary evaporating the filtrate to obtain a polymer-based dispersant; The reaction temperature in (1) is 180-200°C, the reaction time is 10-18h, and vacuum is applied during the reaction; The amount of 5-nitroisophthalic acid in (1) is 100 parts by weight, polyethylene glycol is 230-600 parts by weight, and p-toluenesulfonic acid is 1.2-1.6 parts by weight; The mass fraction of the inorganic alkali aqueous solution in (2) is 70-120 g / L; The amount of the dispersant precursor in (2) is 100 parts by weight, and the amount of sodium dithionite is 85-140 parts by weight; The reaction temperature in (2) is 60-75°C, and the reaction time is 12-18 hours.

2. The process for preparing a polymer-based dispersant according to claim 1, wherein: The molecular weight of the polyethylene glycol is 400-800.

3. The preparation process of the polymer-based dispersant according to claim 1, characterized in that: The inorganic base is sodium hydroxide or potassium hydroxide.

4. A polymer-based dispersant obtained by the preparation process according to any one of claims 1 to 3.

5. Use of the polymer-based dispersant according to claim 4 in the preparation of nanosilver, characterized in that: The preparation method of the nano silver comprises: adding 30-600 parts by weight of a polymer-based dispersant to deionized water, stirring, and then dropwise adding an aqueous solution containing 1 part by weight of silver nitrate; stirring and reacting at 30-60° C. for 18-24 hours in the dark to obtain a nano silver sol; and centrifuging, washing, and drying to obtain the nano silver.

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