阅读说明：本技术 一种氟聚酰亚胺改性hmdi水性聚氨酯固化剂的制备方法 (Preparation method of fluorinated polyimide modified HMDI waterborne polyurethane curing agent ) 是由 谢义鹏 康伦国 姚东生 阳京辉 于 2019-12-06 设计创作，主要内容包括：本发明涉及一种氟聚酰亚胺改性HMDI水性聚氨酯固化剂的制备方法,首先合成氟改性聚酰亚胺多聚体,然后将氟改性聚酰亚胺用于HMDI水性聚氨酯固化剂的改性合成,本发明所述的固化剂具有硬度高、自阻燃性、不易发白、储存稳定的优点。(The invention relates to a preparation method of a fluorine polyimide modified HMDI waterborne polyurethane curing agent, which comprises the steps of firstly synthesizing a fluorine modified polyimide polymer, and then using the fluorine modified polyimide for the modified synthesis of the HMDI waterborne polyurethane curing agent.)

1. A preparation method of a fluorine polyimide modified HMDI waterborne polyurethane curing agent is characterized by comprising the following steps:

(1) preparation of modified polyimide polymer: adding 50 parts of N-methyl pyrrolidone, 8-15 parts of fluorine-containing dianhydride monomer, 0.5-1 part of antioxidant and 0.05-0.2 part of polyphosphoric acid into a reaction kettle equipped with mechanical stirring equipment, temperature control equipment and nitrogen protective atmosphere, starting stirring and dissolving uniformly, heating to 60-80 ℃, then adding 8-12 parts of fluorine-containing diamine monomer, reacting for 2-4h, then adding 8-15 parts of dimethylbenzene, heating to 135-155 ℃, reacting for 12-24h, removing water generated in the reaction through reflux equipment in the reaction process, and finally removing micromolecules through reduced pressure distillation until the polymer content is greater than 98%, namely the modified polyimide polymer;

(2) preparing a polyether modified HMDI waterborne polyurethane curing agent: adding 10-20 parts of modified polyimide polymer into a dripping kettle, heating and dehydrating for 2 hours in vacuum, and introducing N₂Sealing for later use; adding 15-30 parts of inert solvent into a synthesis kettle, heating and dehydrating for 2 hours in vacuum, and introducing N₂Then adding 60-90 parts of HMDI hydrogenated diphenylmethane diisocyanate, heating to dissolve, adding modified polyimide polymer in a dropwise manner, and keeping constant at 70-80 DEG CReacting for 3-4h at a high temperature, starting sampling after reacting for 2h, sampling once every 0.5h, detecting the NCO content, adding 4-9 parts of waterborne reagent when the NCO content is 18-25%, reacting for 1-2h at a high temperature, adding 0.1-0.5 part of 2,4, 6-tris (dimethylaminomethyl) phenol when the NCO content is 10-15%, immediately cooling to 20 ℃ to stop the reaction, adding dimethylethanolamine to neutralize until the pH of the system is =7.0, removing impurities by using a thin film distillation method, and filtering to obtain the polyimide fluoride modified HMDI waterborne polyurethane curing agent.

2. The method for preparing the fluorinated polyimide modified HMDI waterborne polyurethane curing agent of claim 1, wherein the fluorine-containing dianhydride monomer is at least one of 6,6 '-bis-trifluoromethyl-2, 3,3',4 '-biphenyl tetracarboxylic dianhydride, 4' -hexafluoroisopropyl phthalic anhydride, triptycene-4, 5-bis-trifluoromethyl-2, 3,6, 7-tetracarboxylic dianhydride; the fluorine-containing diamine monomer is at least one of 5,5' -hexafluoroisopropyl-bis (-2 aminophenol) and 2,2 ' -ditrifluoromethyl-4, 4' -diaminodiphenyl ether; the antioxidant is at least one of tetramethyl benzoquinone, 2-methyl-2-nitrosomethane, 2-diphenyl-1-trinitrophenyl hydrazine (DPPH), p-benzoquinone and phenyl-N-tert-butyl nitrone.

3. The method for preparing the fluoropolyimide modified HMDI waterborne polyurethane curing agent as claimed in claim 1, wherein the inert solvent is free of water, and is selected from one or a combination of diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate and dipropylene glycol methyl ether acetate; the water-based reagent is at least one of dihydroxypropionic acid, 3-hydroxypropionic acid and lactic acid.

Technical Field

The invention relates to a preparation method of a fluorinated polyimide modified HMDI waterborne polyurethane curing agent, belonging to the technical field of environment-friendly synthesis.

Technical Field

The waterborne polyurethane curing agent mainly comprises aromatic and aliphatic groups. The aromatic polyisocyanate curing agent mainly comprises TDI trimer and TDI-TMP adduct. The TDI tripolymer has the advantages of high functionality, low viscosity, higher thermal stability, good corrosion resistance and the like, can be used as a curing agent of a two-component polyurethane coating, can enable a coating film to have excellent performances such as quick drying, high hardness and the like, and can be widely applied to quick-drying type matt paint, bright paint and other varieties; TDI-TMP is a common polyurethane curing agent at present, has good comprehensive performance, moderate curing speed, good storage stability, moderate film forming strength and good heat resistance, and is mainly applied to priming paint, anticorrosive paint and furniture paint of various coating systems. The aliphatic polyisocyanate curing agent mainly comprises HDI biuret and HDI tripolymer, has excellent chemical resistance and weather resistance (no yellowing, light retention and chalking resistance), and is widely applied to the fields of aviation, automobiles, ships and the like; because of the existence of the isocyanic urea ester ring, the HDI tripolymer is not decomposed at a certain high temperature, so the HDI tripolymer has the advantages of good thermal stability, good wear resistance, good corrosion resistance and the like, and is often used as a polyurethane curing agent in the fields of furniture, automobile industry, aviation industry, sports equipment and the like.

Aromatic and aliphatic polyisocyanate curing agents are widely used as polyurethane curing agents because of their excellent properties, but both have certain limitations. Due to the existence of an induction effect, the-NCO of the aromatic isocyanate has a high reaction speed with water, and is poor in water dispersibility and storage stability when used as a waterborne polyurethane curing agent after hydrophilic modification, and meanwhile, the aromatic isocyanate is easy to oxidize and generate yellowing due to the existence of a benzene ring; the aliphatic polyisocyanate curing agent has low-NCO activity, and the hydrophilic modified curing agent reacts with water slowly, which contributes to the prolongation of the pot life.

Disclosure of Invention

In order to overcome the defects and shortcomings of the prior art, the invention aims to provide a preparation method of a fluorinated polyimide modified HMDI waterborne polyurethane curing agent.

The invention provides the following technical scheme, and discloses a preparation method of a fluorine polyimide modified HMDI waterborne polyurethane curing agent, which is characterized by comprising the following steps in parts by weight:

a preparation method of a fluorine polyimide modified HMDI waterborne polyurethane curing agent is characterized by comprising the following steps:

(1) preparation of modified polyimide polymer: adding 50 parts of N-methyl pyrrolidone, 8-15 parts of fluorine-containing dianhydride monomer, 0.5-1 part of antioxidant and 0.05-0.2 part of polyphosphoric acid into a reaction kettle equipped with mechanical stirring equipment, temperature control equipment and nitrogen protective atmosphere, starting stirring and dissolving uniformly, heating to 60-80 ℃, then adding 8-12 parts of fluorine-containing diamine monomer, reacting for 2-4h, then adding 8-15 parts of dimethylbenzene, heating to 135-155 ℃, reacting for 12-24h, removing water generated in the reaction through reflux equipment in the reaction process, and finally removing micromolecules through reduced pressure distillation until the polymer content is greater than 98%, namely the modified polyimide polymer.

(2) Preparing a polyether modified HMDI waterborne polyurethane curing agent: adding 10-20 parts of modified polyimide polymer into a dripping kettle, heating and dehydrating for 2 hours in vacuum, and introducing N₂Sealing for later use; adding 15-30 parts of inert solvent into a synthesis kettle, heating and dehydrating for 2 hours in vacuum, and introducing N₂Then adding 60-90 parts of HMDI hydrogenated diphenylmethane diisocyanate, heating for dissolving, adding a modified polyimide polymer in a dropwise manner, keeping constant temperature at 70-80 ℃ for reaction for 3-4h, starting sampling after reaction for 2h, sampling every 0.5h, detecting the NCO content, adding 4-9 parts of a waterborne reagent when the NCO content is 18-25%, keeping the temperature for reaction for 1-2h, adding 0.1-0.5 part of 2,4, 6-tris (dimethylaminomethyl) phenol when the NCO content is 10-15%, immediately cooling to 20 ℃ to stop the reaction, adding dimethylethanolamine for neutralization until the pH of the system is =7.0, removing impurities by using a thin film distillation method, and filtering to obtain the fluorinated polyimide modified HMDI waterborne polyurethane curing agent.

The fluorine-containing dianhydride monomer is at least one of 6,6 '-bis-trifluoromethyl-2, 3,3',4 '-biphenyl tetracarboxylic dianhydride, 4' -hexafluoroisopropyl phthalic anhydride and triptycene-4, 5-bis-trifluoromethyl-2, 3,6, 7-tetracarboxylic dianhydride; the fluorine-containing diamine monomer is at least one of 5,5' -hexafluoroisopropyl-bis (-2 aminophenol) and 2,2 ' -ditrifluoromethyl-4, 4' -diaminodiphenyl ether; the antioxidant is at least one of tetramethyl benzoquinone, 2-methyl-2-nitrosomethane, 2-diphenyl-1-trinitrophenyl hydrazine (DPPH), p-benzoquinone and phenyl-N-tert-butyl nitrone.

The inert solvent is free of water, and one or a combination of diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate and dipropylene glycol methyl ether acetate is selected; the water-based reagent is at least one of dihydroxypropionic acid, 3-hydroxypropionic acid and lactic acid.

Compared with the prior art, the invention firstly synthesizes the fluorine modified polyimide polymer, and then the fluorine modified polyimide is used for the modified synthesis of the HMDI waterborne polyurethane curing agent.

Detailed Description

The preparation method of the fluorinated polyimide modified HMDI waterborne polyurethane curing agent of the present invention is further described with reference to the following examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention.