Polyurethane dispersant and synthetic method thereof based on carbodiimide

Abstract

The invention belongs to the field of auxiliary chemicals, and particularly relates to a polyurethane dispersant and a synthetic method thereof based on carbodiimide. The synthesis method comprises the following steps: (1) mixing isocyanate with a catalyst, heating for reaction, and obtaining a prepolymer after the content of isocyanate is detected to be qualified; (2) after the temperature is reduced, adding monocarboxyl polyester into the prepolymer, and reacting to obtain an intermediate product; and (3) adding dimethylethanolamine into the intermediate product, heating for reaction, and ending the reaction after detecting that isocyanato disappears, thereby obtaining the polyurethane dispersant. According to the synthetic method disclosed by the invention, polyurethane of carbonized diimine is adopted to prepare the dispersing agent, so that the compatibility with various resins and the dispersing capacity of transparent pigments are improved.

Description

Technical Field

[0001] The present invention belongs to the field of auxiliaries, and particularly relates to a polyurethane dispersant and a synthesis method thereof based on carbodiimide. Background Art

[0002] As the name implies, a dispersant is to reasonably disperse various pigments or powders in a resin solution. Through a certain charge repulsion principle or polymer steric hindrance effect, various solids are stably suspended in a solvent (or dispersion).

[0003] In the process of coating production, pigment dispersion is a very important production link, which is directly related to the storage, construction, appearance and film properties of the coating. The main function of the dispersant used in the coating field is to reduce the viscosity of the dispersion of various color pigments and inorganic fillers, and at the same time, it is required to have good anti-settling ability. Polyurethane dispersants have excellent dispersion performance and are widely used in various coating fields. However, the existing polyurethane dispersant products are synthesized based on isocyanate trimers. The isocyanate trimers have strong rigidity and poor compatibility with resins, resulting in poor performance of the existing polyurethane dispersants for dispersing transparent pigments.

[0004] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a synthesis method of a polyurethane dispersant based on carbodiimide. The synthesis method includes the following steps:

[0006] (1) Mix an isocyanate with a catalyst, heat and react. After the isocyanate content is detected to be qualified, a prepolymer is obtained;

[0007] (2) After the temperature drops, add a monocarboxylic polyester to the prepolymer, and react to obtain an intermediate product;

[0008] (3) Add dimethylethanolamine to the intermediate product, raise the temperature and react. After the isocyanate group disappears, the reaction ends, and the polyurethane dispersant is obtained.

[0009] Preferably, in step (1), the isocyanate is one of TDI, MDI, IPDI, HDI, and HMDI.

[0010] Preferably, in step (1), the catalyst is 3-methyl-1-phenyl-2-phospholene-1-oxide.

[0011] Preferably, in step (1), the reaction temperature is 100-200 °C, and the reaction time is 1-5 h.

[0012] Preferably, in step (2), the molecular weight of the monocarboxylic polyester is 500 to 3000.

[0013] Preferably, in step (2), the reaction temperature is 40 to 60 °C, and the reaction time is 2 to 5 h.

[0014] Preferably, in step (3), the reaction temperature is 60 to 80 °C, and the reaction time is 2 to 5 h.

[0015] Based on the same technical concept, another solution of the present invention is to provide a polyurethane dispersant obtained by the above synthesis method.

[0016] The beneficial effects of the present invention are as follows:

[0017] Existing polyurethane dispersant products are synthesized based on isocyanate trimers. Isocyanate trimers have strong rigidity and slightly poor compatibility with resins, resulting in poor performance of existing polyurethane dispersants for dispersing transparent pigments. The dispersant synthesized by the route of the present invention has good compatibility with resins and improves the performance of dispersing transparent pigments. Detailed implementation manners

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other implementation manners obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention fall within the scope protected by the present invention.

[0019] Example 1

[0020] This example provides a synthesis method of a polyurethane dispersant based on carbodiimide. The synthesis method includes the following steps:

[0021] (1) Add 348 g of toluene diisocyanate (TDI) and 0.1 g of 3-methyl-1-phenyl-2-phospholene-1-oxide with a concentration of 10% into a 3000 ml four-necked flask, and then heat to 100 °C under nitrogen protection and react for 2 h. Then sample and measure the isocyanate content. If the content is less than 27.6 ± 1%, it is qualified. If it is unqualified, continue to react until the isocyanate group is qualified.

[0022] (2) After the isocyanate group reaches the theoretical value, cool down to below 60 °C and add 2000 g of monocarboxylic polyester P1, and react at 45 °C for 2.5 hours.

[0023] (3) Then add 178.4 g of dimethylethanolamine (DMEA), heat to 72 °C and react for 2 h. After testing that the isocyanate group disappears, end the reaction to obtain a polyurethane dispersant with an amine value of 45 mg KOH / g.

[0024] Note: The monocarboxylic polyester P1 is a lauric acid-initiated polycaprolactone valerolactone with a number-average molecular weight of 2000, and the valerolactone content accounts for 20% of the monocarboxylic polyester.

[0025] Example 2

[0026] This example provides a method for synthesizing a polyurethane dispersant based on carbodiimide. The synthesis method includes the following steps:

[0027] (1) Add 870 g of toluene diisocyanate (TDI) and 0.22 g of 3-methyl-1-phenyl-2-phospholene-1-oxide with a concentration of 10% to a 5000-ml four-necked flask, and then heat to 110 °C under nitrogen protection and react for 3 h. After sampling to measure the isocyanate content, if the content is less than 12.1 ± 1%, it is qualified; if not, continue to react until the isocyanate group is qualified.

[0028] (2) After the isocyanate group reaches the theoretical value, cool down to below 60 °C and add 2400 g of monocarboxylic polyester P2, and react at 50 °C for 3 hours.

[0029] (3) Then add 178.4 g of dimethylethanolamine (DMEA), heat to 78 °C and react for 3 hours. After testing that the isocyanate group disappears, end the reaction to obtain a polyurethane dispersant with an amine value of 34.3 mg KOH / g.

[0030] Note: The monocarboxylic polyester P2 is a polycaprolactone initiated by n-decanoic acid with a number-average molecular weight of 600.

[0031] Example 3

[0032] This example provides a method for synthesizing a polyurethane dispersant based on carbodiimide. The synthesis method includes the following steps:

[0033] (1) Add 500 g of diphenylmethane diisocyanate (MDI) and 0.11 g of 3-methyl-1-phenyl-2-phospholene-1-oxide with a concentration of 10% to a 5000-ml four-necked flask, and then heat to 105 °C under nitrogen protection and react for 2 h. After sampling to measure the isocyanate content, if the content reaches 18.4 ± 1%, it is qualified; if not, continue to react until the isocyanate group is qualified.

[0034] (2) After the isocyanate group reaches the theoretical value, cool down to below 60 °C and add 2800 g of monocarboxylic polyester P3, and react at 50 °C for 3 hours.

[0035] (3) Then add 178.4 g of dimethylethanolamine (DMEA), heat to 72 °C and react for 2.5 hours. After testing that the isocyanate group disappears, end the reaction to obtain a polyurethane dispersant with an amine value of 32.6 mg KOH / g.

[0036] Note: The monocarboxyl polyester P3 is a lauric acid-initiated polycaprolactone valerolactone with a number-average molecular weight of 2800, and the valerolactone content accounts for 25% of the monocarboxyl polyester.

[0037] Example 4

[0038] This example provides a method for synthesizing a polyurethane dispersant based on carbodiimide. The synthesis method includes the following steps:

[0039] (1) Add 750 g of diphenylmethane diisocyanate (MDI) and 0.2 g of 3-methyl-1-phenyl-2-phospholene-1-oxide with a concentration of 10% to a 5000-ml four-necked flask. Then, under nitrogen protection, heat the mixture to 100 °C and react for 3.0 h. After that, take a sample to measure the isocyanate content. If the content reaches 12.7 ± 1%, it is qualified; if not, continue the reaction until the isocyanate group is qualified.

[0040] (2) After the isocyanate group reaches the theoretical value, cool the temperature to below 60 °C and add 3600 g of monocarboxyl polyester P4, and react at 55 °C for 3.0 hours.

[0041] (3) Then add 178.4 g of dimethylethanolamine (DMEA), heat the mixture to 75 °C and react for 2 hours. After testing that the isocyanate group has disappeared, end the reaction to obtain a polyurethane dispersant with an amine value of 25.3 mg KOH / g.

[0042] Note: The monocarboxyl polyester P4 is a lauric acid-initiated polycaprolactone valerolactone with a number-average molecular weight of 1800, and the valerolactone content accounts for 18% of the monocarboxyl polyester.

[0043] Example 5

[0044] This example provides a method for synthesizing a polyurethane dispersant based on carbodiimide. The synthesis method includes the following steps:

[0045] (1) Add 666 g of isophorone diisocyanate (IPDI) and 3.0 g of 3-methyl-1-phenyl-2-phospholene-1-oxide with a concentration of 10% to a 5000-ml four-necked flask. Then, under nitrogen protection, heat the mixture to 180 °C and react for 3 h. After that, take a sample to measure the isocyanate content. If the content reaches 14.5 ± 1%, it is qualified; if not, continue the reaction until the isocyanate group is qualified.

[0046] (2) After the isocyanate group reaches the theoretical value, cool the temperature to below 60 °C and add 2800 g of monocarboxyl polyester P5, and react at 55 °C for 3.5 hours.

[0047] (3) Then add 178.4 g of dimethylethanolamine (DMEA), heat the mixture to 78 °C and react for 4 hours. After testing that the isocyanate group has disappeared, end the reaction. Obtain a polyurethane dispersant with an amine value of 31.5 mg KOH / g.

[0048] Note: The monocarboxylic polyester P5 is a polycaprolactone valerolactone initiated with lauric acid, with a number average molecular weight of 1400, and the valerolactone content accounts for 15% of the monocarboxylic polyester.

[0049] Example 6

[0050] This example provides a method for synthesizing a polyurethane dispersant based on carbodiimide. The synthesis method includes the following steps:

[0051] (1) Add 888 g of isophorone diisocyanate (IPDI) and 5.1 g of 3-methyl-1-phenyl-2-phospholene-1-oxide with a concentration of 10% into a 5000 ml four-necked flask, and then heat to 190 °C under nitrogen protection and react for 3.5 h. After sampling, measure the isocyanate content. If the content reaches 11.1 ± 1%, it is qualified; if not, continue to react until the isocyanate group is qualified.

[0052] (2) After the isocyanate group reaches the theoretical value, cool down to below 60 °C and add 3000 g of monocarboxylic polyester P6, and react at 55 °C for 4.5 hours.

[0053] (3) Then add 178.4 g of dimethylethanolamine (DMEA), heat up to 72 °C and react for 4.5 hours. After testing that the isocyanate group disappears, end the reaction to obtain a polyurethane dispersant with an amine value of 28.5 mg KOH / g.

[0054] Note: The monocarboxylic polyester P6 is a polycaprolactone valerolactone initiated with lauric acid, with a number average molecular weight of 1000, and the valerolactone content accounts for 10% of the monocarboxylic polyester.

[0055] Evaluation and comparison:

[0056] The formulation of the color paste grinding is shown in Table 1.

[0057] Table 1

[0058] Raw materials Dosage 179 Red 6 1K Resin (Yake 304) 60 Dispersant (50%) 6 Propylene Glycol Methyl Ether Acetate 28

[0059] The formulation of the flash silver paint is shown in Table 2.

[0060] Table 2

[0061]

[0062]

[0063] The evaluation results are shown in Table 3.

[0064] Table 3

[0065]

[0066] Note: The evaluation results are divided into four grades: A, B, C, and D, and the effects are in descending order, with A being the best and D being the worst.

Claims

1. A method for synthesizing a polyurethane dispersant based on carbonized diimide, characterized in that: The synthesis method comprises the following steps: (1) mixing isocyanate and a catalyst, heating to react, and obtaining a prepolymer after the isocyanate content is tested to be qualified; (2) after the temperature is lowered, adding monocarboxyl polyester to the prepolymer to obtain an intermediate product after reaction; (3) adding dimethylethanolamine to the intermediate product, heating the product to react, and terminating the reaction after the isocyanate group disappears, thereby obtaining the polyurethane dispersant.

2. The method for synthesizing the polyurethane dispersant based on carbonized diimide according to claim 1, characterized in that: In step (1), the isocyanate is one of TDI, MDI, IPDI, HDI and HMDI.

3. The method for synthesizing a polyurethane dispersant based on carbonized diimide according to claim 1, characterized in that: In step (1), the catalyst is 3-methyl-1-phenyl-2-phosphocyclopentene-1-oxide.

4. The method for synthesizing a polyurethane dispersant based on carbonized diimide according to claim 1, characterized in that: In step (1), the reaction temperature is 100-200° C., and the reaction time is 1-5 h.

5. The method for synthesizing a polyurethane dispersant based on carbonized diimide according to claim 1, characterized in that: In step (2), the molecular weight of the monocarboxyl polyester is 500 to 3000.

6. The method for synthesizing a polyurethane dispersant based on carbonized diimide according to claim 1, characterized in that: In step (2), the reaction temperature is 40 to 60° C., and the reaction time is 2 to 5 hours.

7. The method for synthesizing a polyurethane dispersant based on carbonized diimide according to claim 1, characterized in that: In step (3), the reaction temperature is 60-80° C. and the reaction time is 2-5 h.

8. The polyurethane dispersant obtained by the synthesis method according to any one of claims 1 to 7.

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