A method for preparing a dispersant for ceramics

Abstract

The present invention relates to the technical field of ceramic dispersants, and discloses a method for preparing a ceramic dispersant. The present invention uses polyethylene glycol monomethyl ether, bromoacetyl bromide, 4-hydroxyphthalic anhydride and 2,4,6-diethanolamino-1,3,5-s-triazine as raw materials to prepare a novel ceramic dispersant. It contains multiple carboxyl groups, has a strong interaction with the surface of ceramic powders such as aluminum oxide, and has a star-shaped multi-arm polyether molecular chain, can be well coated with aluminum oxide powder, can effectively inhibit the growth of aluminum oxide powder crystal nucleus particle size, reduce the particle size of aluminum oxide, avoid agglomeration and sedimentation, and the modified aluminum oxide ceramic powder has a good activation degree in water, ethanol, dichloromethane or N, N-dimethylformamide and other solvents, and a lower sedimentation volume, showing excellent dispersion properties.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic dispersants, in particular to a method for preparing a ceramic dispersant. Background Art

[0002] Ceramic products mainly include alumina ceramics, calcium carbonate ceramics, iron oxide ceramics, silicate ceramics, etc., which are widely used in electric heating appliances, building materials, petrochemicals and other fields. Among them, ceramic slurries such as alumina have poor dispersibility and stability, which is not conducive to the molding of ceramic products and will affect the mechanical properties of the embryo and ceramics. The development of high-performance ceramic dispersants is of great significance.

[0003] At present, the dispersants for inorganic powders such as aluminum oxide mainly include polyethylene glycol, polyoxyethylene ether, polycarboxylic acid, polyacrylamide, etc. The Chinese invention patent with the announcement number CN108408720B discloses the use of a star-shaped sulfonic acid zwitterionic surfactant as a dispersant, which reacts a long-chain fatty primary amine with a trimethylolpropane-tris (3-aziridinyl propionate) reaction solution, and then reacts with sodium 2-chloroethylsulfonate to prepare a star-shaped sulfonic acid zwitterionic surfactant as a dispersant, which improves the dispersibility of inorganic powders such as aluminum oxide and zinc oxide in water. However, the dispersant does not improve the dispersibility of aluminum oxide and other powders in organic solvents such as ethanol and N,N-dimethylformamide. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a ceramic dispersant, and the obtained dispersant solves the problem of poor dispersibility of ceramic powders such as alumina.

[0005] To achieve this object, the present invention adopts the following technical solution: a method for preparing a ceramic dispersant, comprising the following steps:

[0006] Step A, add dichloromethane, polyethylene glycol monomethyl ether and triethylamine to a reaction vessel, introduce nitrogen, add a dichloromethane solution of bromoacetyl bromide in an ice-water bath, then react at 20-25°C for 12-18h, rotary evaporate until a large amount of precipitate is precipitated, filter to remove the generated triethylamine hydrochloride, rotary evaporate the filtrate, wash the product with a saturated sodium chloride solution, and dry to obtain bromoacetate polyethylene glycol monomethyl ether. The reaction formula is:

[0007] .

[0008] Step B, add acetonitrile, potassium carbonate and 4-hydroxyphthalic anhydride to a reaction vessel, add bromoacetate polyethylene glycol monomethyl ether after heating and stirring, then heat to 65-75°C, react for 18-24h, cool, filter, rotary evaporate the filtrate, wash the product with saturated sodium chloride solution, then dissolve it in tetrahydrofuran, heat to volatilize, cool and recrystallize to obtain phthalic anhydride polyethylene glycol monomethyl ether. The reaction formula is:

[0009] .

[0010] Step C, add solvent, 2,4,6-diethanolamino-1,3,5-s-triazine (CAS registration number is 4403-08-1) and triethylamine to the reaction container, introduce nitrogen, add phthalic anhydride polyethylene glycol monomethyl ether in an ice water bath, and then react for 2-3 hours at 20-25°C, rotary evaporate until a large amount of precipitate is precipitated, filter to remove the generated triethylamine hydrochloride, rotary evaporate the filtrate, wash the product with a saturated sodium chloride solution, then dissolve it in tetrahydrofuran, heat to volatilize, cool and recrystallize to obtain a ceramic dispersant. The reaction formula is:

[0011] .

[0012] Furthermore, in step A, the ratio of polyethylene glycol monomethyl ether, triethylamine and bromoacetyl bromide is 1 mol: (1.8-2.4) mol: (2-2.5) mol. The molecular weight of polyethylene glycol monomethyl ether is 750-1200.

[0013] Furthermore, in step B, the ratio of potassium carbonate, 4-hydroxyphthalic anhydride (CAS registration number is 27550-59-0), and bromoacetate polyethylene glycol monomethyl ether is (3-4) mol: (2.4-3.2) mol: 1 mol.

[0014] Furthermore, in step C, the solvent is dichloromethane or tetrahydrofuran.

[0015] Furthermore, in step C, the ratio of 2,4,6-diethanolamino-1,3,5-s-triazine, triethylamine and phthalic anhydride-based polyethylene glycol monomethyl ether is 1 mol: (6-7.2) mol: (6.6-8.4) mol.

[0016] One of the above technical solutions has the following beneficial effects: the present invention uses cheap and readily available polyethylene glycol monomethyl ether, bromoacetyl bromide, 4-hydroxyphthalic anhydride and 2,4,6-diethanolamino-1,3,5-s-triazine as raw materials to prepare a new type of ceramic dispersant. It contains multiple carboxyl groups and has a strong interaction with the surface of ceramic powders such as alumina. It also has a star-shaped multi-arm polyether molecular chain, which can well coat the alumina powder, effectively inhibit the growth of the alumina powder crystal nucleus particle size, reduce the alumina particle size, and avoid agglomeration and sedimentation. The modified alumina ceramic powder has a good activation degree in solvents such as water, ethanol, dichloromethane or N,N-dimethylformamide, a lower sedimentation volume, and exhibits excellent dispersion performance. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1: Step A, add 100mL of dichloromethane, 10mmol of polyethylene glycol monomethyl ether 1000, and 24mmol of triethylamine to a reaction vessel, introduce nitrogen, add 20mL of a dichloromethane solution containing 25mmol of bromoacetyl bromide in an ice-water bath, and then react at 20°C for 18h, rotary evaporation until a large amount of precipitate is precipitated, and the generated triethylamine hydrochloride is filtered out, the filtrate is rotary evaporated, the product is washed with a saturated sodium chloride solution, and dried to obtain bromoacetate polyethylene glycol monomethyl ether.

[0019] Step B, add 50mL acetonitrile, 15mmol potassium carbonate, 12mmol 4-hydroxyphthalic anhydride to the reaction container, add 5mmol bromoacetate polyethylene glycol monomethyl ether after heating and stirring, then raise the temperature to 70°C, react for 18h, cool, filter, and rotary evaporate the filtrate. The product is washed with saturated sodium chloride solution, then dissolved in tetrahydrofuran, heated for volatilization, cooled for recrystallization, and phthalic anhydride polyethylene glycol monomethyl ether is obtained.

[0020] Step C, add 300mL of dichloromethane solvent, 2mmol of 2,4,6-diethanolamino-1,3,5-s-triazine, and 12mmol of triethylamine into a reaction container, introduce nitrogen, add 14.4mmol of phthalic anhydride-based polyethylene glycol monomethyl ether in an ice-water bath, and then react at 20°C for 3h, rotary evaporate until a large amount of precipitate is precipitated, filter out the generated triethylamine hydrochloride, rotary evaporate the filtrate, wash the product with a saturated sodium chloride solution, then dissolve it in tetrahydrofuran, heat to volatilize, cool and recrystallize to obtain a ceramic dispersant.

[0021] Example 2: Step A, add 70mL of dichloromethane, 10mmol of polyethylene glycol monomethyl ether 1200, and 18mmol of triethylamine to a reaction vessel, pass nitrogen, add 20mL of a dichloromethane solution containing 20mmol of bromoacetyl bromide in an ice-water bath, and then react at 25°C for 12h, rotary evaporation until a large amount of precipitate is precipitated, and the generated triethylamine hydrochloride is filtered out, the filtrate is rotary evaporated, the product is washed with a saturated sodium chloride solution, and dried to obtain bromoacetate polyethylene glycol monomethyl ether.

[0022] Step B, add 70mL acetonitrile, 20mmol potassium carbonate, 16mmol 4-hydroxyphthalic anhydride to the reaction container, add 5mmol bromoacetate polyethylene glycol monomethyl ether after heating and stirring, then raise the temperature to 65°C, react for 24h, cool, filter, and rotary evaporate the filtrate. The product is washed with saturated sodium chloride solution, then dissolved in tetrahydrofuran, heated for volatilization, cooled for recrystallization, and phthalic anhydride polyethylene glycol monomethyl ether is obtained.

[0023] Step C, add 400mL of tetrahydrofuran solvent, 2mmol of 2,4,6-diethanolamino-1,3,5-s-triazine, and 14.4mmol of triethylamine into a reaction container, introduce nitrogen, add 16.8mmol of phthalic anhydride-based polyethylene glycol monomethyl ether in an ice-water bath, and then react at 20°C for 3h, rotary evaporate until a large amount of precipitate is precipitated, filter out the generated triethylamine hydrochloride, rotary evaporate the filtrate, wash the product with a saturated sodium chloride solution, and then dissolve it in tetrahydrofuran, heat to volatilize, cool and recrystallize to obtain a ceramic dispersant.

[0024] Example 3: Step A, add 70mL of dichloromethane, 10mmol of polyethylene glycol monomethyl ether 750, and 20mmol of triethylamine to a reaction vessel, pass nitrogen, add 20mL of a dichloromethane solution containing 25mmol of bromoacetyl bromide in an ice-water bath, and then react at 20°C for 18h, rotary evaporation until a large amount of precipitate is precipitated, filter out the generated triethylamine hydrochloride, rotary evaporate the filtrate, wash the product with a saturated sodium chloride solution, and dry to obtain bromoacetate polyethylene glycol monomethyl ether.

[0025] Step B, add 70mL acetonitrile, 18mmol potassium carbonate, 16mmol 4-hydroxyphthalic anhydride to the reaction vessel, add 5mmol bromoacetate polyethylene glycol monomethyl ether after heating and stirring, then raise the temperature to 75°C, react for 18h, cool, filter, and rotary evaporate the filtrate. The product is washed with saturated sodium chloride solution, then dissolved in tetrahydrofuran, heated for volatilization, cooled for recrystallization, and phthalic anhydride polyethylene glycol monomethyl ether is obtained.

[0026] Step C, add 350mL of dichloromethane solvent, 2mmol of 2,4,6-diethanolamino-1,3,5-s-triazine, and 12mmol of triethylamine into a reaction container, introduce nitrogen, add 13.2mmol of phthalic anhydride-based polyethylene glycol monomethyl ether in an ice-water bath, and then react at 25°C for 2h, rotary evaporate until a large amount of precipitate is precipitated, filter out the generated triethylamine hydrochloride, rotary evaporate the filtrate, wash the product with a saturated sodium chloride solution, then dissolve it in tetrahydrofuran, heat to volatilize, cool and recrystallize to obtain a ceramic dispersant.

[0027] In Comparative Example 1, polyethylene glycol monomethyl ether 1000 was used as the dispersant.

[0028] In Comparative Example 2, bromoacetate polyethylene glycol monomethyl ether (prepared in step A of Example 1) was used as the dispersant.

[0029] Comparative Example 3 uses phthalic anhydride-based polyethylene glycol monomethyl ether (prepared by steps A and B of Example 1) as a dispersant.

[0030] Add 10 g of alumina powder (average particle size 300 nm) to water, disperse by ultrasonic, add 0.1 g of the above dispersant, stir at 30° C. for 2 h, filter, wash with water, and dry to obtain modified alumina powder.

[0031] Weigh 1g (m0) of modified alumina powder, add it to 100mL of solvent, ultrasonicate for 30min and stir it thoroughly, then let it stand for 12h, collect the precipitated modified nano-alumina, dry it at 100℃ for 12h, weigh it (m1), and calculate the activation degree W, W=(m0-m1 / m0)×100%. The test results are shown in Table 1.

[0032] Weigh 1g (m0) of modified alumina powder, add it to a measuring cylinder containing 10mL of solvent, ultrasonicate for 30min and mix thoroughly, let it stand for 72h, measure the volume of the sediment (V), and calculate the sedimentation volume Q. Q = (V / m0). The test results are shown in Table 2.

[0033] Table 1: Activation degree in different solvents

[0034]

[0035] Table 2: Sedimentation volumes in different solvents

[0036]

[0037] It can be seen from Table 1 and Table 2 that, compared with the dispersants of Comparative Examples 1-3, after the dispersants prepared in Examples 1-3 modify the alumina powder, the activation degree of alumina in solvents such as water or ethanol is higher, the sedimentation volume is lower, and the dispersibility is better. This is mainly because the dispersants prepared in each example contain multiple carboxyl groups, have stronger interaction forces on the surface of the alumina powder, and have star-shaped multi-arm polyether molecular chains, which can well coat the alumina powder, effectively inhibit the growth of the alumina powder crystal nucleus particle size, reduce the particle size of alumina, avoid its agglomeration and sedimentation, and show good dispersibility.

[0038] Add 10 g of alumina powder (average particle size 300 nm) to water, disperse by ultrasonic, add 0.1-0.4 g of dispersant (prepared in Example 1), stir at 30° C. for 2 h, filter, wash with water, and dry to obtain modified alumina powder.

[0039] Weigh 1g (m0) of modified alumina powder, add it to 100mL of solvent, ultrasonicate for 30min and stir thoroughly, then let it stand for 12h, collect the precipitated modified nano-alumina, dry it at 100℃ for 12h, weigh it (m1), and calculate the activation degree W, W= (m0-m1 / m0)×100%.

[0040] Weigh 1g (m0) of modified alumina powder, add it to a measuring cylinder filled with 10mL of solvent, ultrasonicate for 30min and mix thoroughly, let it stand for 72h, measure the volume of the sediment (V), and calculate the sedimentation volume Q. Q = (V / m0).

[0041] Table 3: Activation degree in different solvents

[0042]

[0043] Table 4: Sedimentation volumes in different solvents

[0044]

[0045] It can be seen from Tables 3 and 4 that the modification of alumina using different amounts of dispersants all showed good activation and low sedimentation volume, and the alumina powder had excellent dispersibility.

[0046] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a ceramic dispersant, characterized in that: The preparation method comprises the following steps: Step A, adding dichloromethane, polyethylene glycol monomethyl ether and triethylamine into a reaction container, passing nitrogen, adding a dichloromethane solution of bromoacetyl bromide in an ice-water bath, and then reacting, rotary evaporating until a precipitate is precipitated, filtering, rotary evaporating the filtrate, washing, and drying to obtain bromoacetate polyethylene glycol monomethyl ether; Step B, adding acetonitrile, potassium carbonate and 4-hydroxyphthalic anhydride into a reaction container, adding bromoacetate polyethylene glycol monomethyl ether after heating and stirring, then reacting, cooling, filtering, rotary evaporating the filtrate, washing the product and recrystallizing it to obtain phthalic anhydride-based polyethylene glycol monomethyl ether; Step C, adding a solvent, 2,4,6-diethanolamino-1,3,5-s-triazine and triethylamine into a reaction container, introducing nitrogen, adding phthalic anhydride-based polyethylene glycol monomethyl ether in an ice-water bath, and then reacting, rotary evaporating until a precipitate is precipitated, filtering, rotary evaporating the filtrate, washing the product and then recrystallizing it to obtain a ceramic dispersant; In the step C, the ratio of 2,4,6-diethanolamino-1,3,5-s-triazine, triethylamine and phthalic anhydride-based polyethylene glycol monomethyl ether is 1 mol: (6-7.2) mol: (6.6-8.4) mol.

2. The method for preparing a ceramic dispersant according to claim 1, characterized in that: In the step A, the ratio of polyethylene glycol monomethyl ether, triethylamine and bromoacetyl bromide is 1 mol: (1.8-2.4) mol: (2-2.5) mol.

3. The method for preparing a ceramic dispersant according to claim 2, characterized in that: The molecular weight of the polyethylene glycol monomethyl ether is 750-1200.

4. The method for preparing a ceramic dispersant according to claim 1, characterized in that: The reaction in step A is carried out at 20-25° C. for 12-18 hours.

5. The method for preparing a ceramic dispersant according to claim 1, characterized in that: In the step B, the ratio of potassium carbonate, 4-hydroxyphthalic anhydride and bromoacetate polyethylene glycol monomethyl ether is (3-4) mol: (2.4-3.2) mol: 1 mol.

6. The method for preparing a ceramic dispersant according to claim 1, characterized in that: The reaction in step B is carried out at 65-75° C. for 18-24 h.

7. The method for preparing a ceramic dispersant according to claim 1, characterized in that: The solvent in step C is dichloromethane or tetrahydrofuran.

8. The method for preparing a ceramic dispersant according to claim 1, characterized in that: The reaction in step C is carried out at 20-25° C. for 2-3 hours.

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