CN109517139B - Water dispersible polyisocyanate composition and preparation method thereof - Google Patents

Abstract

The invention relates to the field of two-component water-based resins, and relates to a water-dispersible polyisocyanate composition and a preparation method thereof. The composition is configured according to the mass ratio of the hydrophilic modified polyisocyanate curing agent and the aromatic polyisocyanate in a ratio of 10:1 to 1:3, and the NCO content is 15 to 25% of the total mass of the water-dispersible polyisocyanate composition. %, and contains fluorine-containing polyether segments and zwitterionic segments; the preparation steps are S1, synthesizing a hydrophilic modified polyisocyanate curing agent; S2, adding aromatic polyisocyanate to the hydrophilic modified polyisocyanate under nitrogen protection In the isocyanate curing agent, stir and mix for 5-40min to obtain a water-dispersible polyisocyanate composition. The invention solves the defects of short pot life and high production cost of the water-dispersible polyisocyanate in the prior art, and obtains a low-cost and high-performance water-dispersible polyisocyanate composition.

Description

A kind of water-dispersible polyisocyanate composition and preparation method thereof

technical field

The invention relates to the technical field of two-component water-based resins, and more particularly, to a water-dispersible polyisocyanate composition and a preparation method thereof.

Background technique

The cost of aromatic polyisocyanates is lower, and at the same time, the properties of the cured products after being compounded with hydroxyl components are also better. Johnson et al. proposed in US Pat. No. 3,996,154 that the reaction product of polyethylene glycol methyl ether and MDI, TDI, and PAPI was used as a surfactant, and then mixed with MDI, TDI, and PAPI to prepare water-based aromatic polyisocyanates. However, aromatic polyisocyanates are highly reactive and react quickly with water, making their pot life in water very short. In US Pat. No. 4,663,377, Rudolf et al. prepared a water-dispersible polyisocyanate by reacting a mixture of MDI with a mass fraction of 60% and a PAPI with a mass fraction of 40% with a monofunctional polyoxyethylene alcohol, and the pot life was still short. Due to the presence of benzene rings in aromatic polyisocyanates, an induction effect occurs between -NCO groups, the reactivity of isocyanates is greatly increased, and the reaction rate with water is much higher than that of aliphatic polyisocyanates. It reacts with water quickly to form urea, which makes the crosslinking density of the coating rise rapidly and the pot life is shortened. Therefore, although hydrophilically modified aromatic polyisocyanates have obvious advantages in terms of cost and performance, they cannot be used as two-component waterborne polyurethane curing agents at present.

Currently, the widely used water-dispersible polyisocyanate crosslinking agents on the market are nonionic or anionic modified aliphatic or cycloaliphatic polyisocyanate compositions. US Patents US5194487 and US6426414 reported the use of polyethers to carry out hydrophilic modification of aliphatic polyisocyanates, thus making the practical application of two-component waterborne polyurethane coatings possible. However, the emulsification of the polyether-modified polyisocyanate curing agent in the hydroxyl-based water-based polyol emulsion is not ideal, and it needs a strong machine to be dispersed uniformly. US Patents US5583176 and US6767958B2 use sulfonate compounds containing active hydrogen to carry out hydrophilic modification on polyisocyanates, and the obtained polyisocyanate curing agents show good emulsifying properties. This sulfonic acid anion-modified polyisocyanate curing agent has been widely used in practical applications. However, the hydrophilicity of the highly emulsifying polyisocyanate after hydrophilic modification is too strong. When it is mixed with the hydroxyl emulsion, the isocyanate (-NCO) group easily reacts with water, resulting in the dispersion of polyisocyanate in the The pot life in water is short.

The pot life of two-component aqueous polyurethane systems prepared with existing anionic or nonionic modified polyisocyanate curing agents is still relatively short. In Chinese patent CN1085682C, Shinichiro Watanabe and others proposed to use polyether containing polyethylene glycol chain segment to conduct hydrophilic modification on polyisocyanate, and then compound a certain amount of ionic surfactant, the obtained composition has high emulsifying and long pot life. However, the ionic surfactant mentioned in it does not bond with the polyisocyanate, and as a plasticizer, it will adversely affect the performance of the final two-component waterborne polyurethane cured product. In Chinese patent CN101443378B, Nakano Takahi and others proposed to use polyethers with hydroxyl groups and ethylene oxide chains in the majority, polyethers with hydroxyl groups and propylene oxide chains in the majority, and sulfonic acids with hydroxyl groups. The aliphatic polyisocyanate is modified by the mixed modifier composed of the esterified product of the alkali metal salt, thereby increasing the pot life of the polyisocyanate curing agent. In this polyisocyanate composition, the hydroxyl-terminated polyether with 8 or more carbon alcohol as the initiator and propylene oxide as the main body can protect the isocyanate group due to the hydrophobic effect, while the sulfonate modifier It is hydrophilic with ethylene oxide as the main polyether modifier, which can impart emulsifying properties to polyisocyanates. However, since the amount of the hydrophilic modifier is much smaller than that of the polyisocyanate, it is difficult for the hydrophobic group and the hydrophilic group to bond to the same polyisocyanate molecule. When the polyisocyanate composition is dispersed in water, the polyisocyanate molecules bound with hydrophilic modifying groups are in the outer layer of the emulsion droplets, while the polyisocyanate molecules bound with hydrophobic modifying groups tend to be in the outer layer of the emulsion droplets. In the inner layer, the long hydrophobic chain cannot effectively protect the -NCO group of the polyisocyanate molecule in the outer layer of the emulsion droplet, and has limited effect on prolonging the pot life of the polyisocyanate. Moreover, the introduction of the hydrophobic modification group also consumes the -NCO group, which reduces the performance of the curing agent. Therefore, the methods disclosed in the above patents cannot effectively improve the pot life of the two-component waterborne polyurethane curing agent and reduce the performance of the curing agent. The zwitterionic polyether-modified polyisocyanate curing agent used in Chinese patent CN103483574.A can delay the reaction of water and -NCO groups to a certain extent, but the hydrophobicity of polypropylene glycol is low, and its shielding protection for -NCO groups The effect is limited.

At present, regardless of non-ionic modification or anionic modification, the base materials used in the two-component waterborne polyurethane curing agent are all aliphatic or alicyclic polyisocyanates, which results in high product cost, which is not suitable for the two-component waterborne polyurethane curing agent. The use and promotion of it has caused great obstacles. In addition, due to the introduction of hydrophilic substances, the water resistance of the cured product of this aliphatic water-dispersible polyisocyanate is still not high. Moreover, due to its aliphatic structure, the mechanical properties of its cured product are not ideal. In order to improve the water resistance and mechanical properties of the cured product, it is necessary to increase the crosslinking density of the cured product and increase the amount of polyisocyanate, thereby further increasing the cost.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a water-dispersible polyisocyanate composition and a preparation method thereof, so as to solve the defects of short pot life and high production cost of water-dispersible polyisocyanates in the prior art.

A water-dispersible polyisocyanate composition, comprising a hydrophilic modified polyisocyanate curing agent and an aromatic polyisocyanate; wherein, the mass ratio of the hydrophilic modified polyisocyanate curing agent to the aromatic polyisocyanate is 10:1-1 : 3, and the NCO content is 15-25% of the total mass of the water-dispersible polyisocyanate composition, and the water-dispersible polyisocyanate composition contains a fluorine-containing polyether segment and a zwitterionic segment.

As a preferred solution of the present invention, the aromatic polyisocyanate is an aromatic diisocyanate and a trimer or multimer derivative of aromatic diisocyanate, that is, the aromatic polyisocyanate is a trimer derivative of aromatic diisocyanate, Or the aromatic polyisocyanate is a polymer derivative of an aromatic diisocyanate, or the aromatic polyisocyanate is an aromatic diisocyanate, or the aromatic polyisocyanate is an aromatic diisocyanate and a polymer derivative of an aromatic diisocyanate or the aromatic polyisocyanates are aromatic diisocyanates and trimer derivatives of aromatic diisocyanates, or the aromatic polyisocyanates are polymers of aromatic diisocyanates and aromatic diisocyanates, or the aromatic polyisocyanates Isocyanates are aromatic diisocyanates and trimers of aromatic diisocyanates.

As a preferred solution of the present invention, the aromatic polyisocyanates are toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, tetramethyl xylylene diisocyanate and polymeric diisocyanate One or more mixtures of phenylmethane diisocyanates.

As a preferred solution of the present invention, the mass ratio of the hydrophilic modified polyisocyanate curing agent to the aromatic polyisocyanate is 5:1 to 1:1, and the NCO content is 17 to 17 of the total mass of the water-dispersible polyisocyanate composition. twenty three%.

As a preferred solution of the present invention, the hydrophilic modified polyisocyanate curing agent is synthesized by reacting an aliphatic or alicyclic polyisocyanate with a fluorine-containing polyether hydrophilic modifier, and the fluorine-containing polyether is hydrophilically modified The mass of the agent accounts for 10.0-50.0% of the total mass of the hydrophilic modified polyisocyanate curing agent, and the molecular structure of the fluorine-containing polyether hydrophilic modifier is shown in formula A

Wherein, R _f is a fluorine-containing alkyl group; R is an alkyl group; x is an integer of 1-20; y is an integer of 1-20.

As a preferred embodiment of the present invention, R _f is specifically trifluoromethyl-CF ₃ , pentafluoroethyl-CH ₂ CF ₃ , tetrafluoropropyl-CH ₂ CF ₂ CF ₂ H, perfluorobutyl-(CF ₂ ) ₃ CF ₃ , perfluorohexyl-(CF ₂ ) ₅ CF ₃ , perfluorooctyl-(CF ₂ ) ₇ CF ₃ or perfluorohexylethyl-CH ₂ CH ₂ (CF ₂ ) ₅ CF ₃ ; R is specific is ethyl _{- CH2CH3} , _{propyl - CH2CH2CH3} or butyl _{- CH2CH2CH2CH3 ;} x is an integer _of 1-10; y is an integer of 1-10.

As a preferred solution of the present invention, the sulfoalkyl betaine groups in the water-dispersible polyisocyanate composition account for 0.4-9.1% of the total mass, and the mass ratio of the fluorine-containing polyether hydrophilic modifier accounts for 2.5 to 45.5% of the total mass.

As a preferred solution of the present invention, the sulfoalkyl betaine groups in the water-dispersible polyisocyanate composition account for 1.4-6.6% of the total mass, and the mass ratio of the fluorine-containing polyether hydrophilic modifier accounts for 10.0 to 33.3% of the total mass.

A preparation method of a water-dispersible polyisocyanate composition for preparing the water-dispersible polyisocyanate composition according to any one of claims 1-8, which is prepared as follows:

S1. Synthesis of hydrophilic modified polyisocyanate curing agent: firstly synthesize fluorine-containing polyether hydrophilic modifier; then under nitrogen protection, heat polyisocyanate to 70-100℃; then add fluorine-containing polyether hydrophilic modifier into the reactor The water modifier is reacted in the presence of the catalyst dibutyltin dilaurate, wherein the mass of the fluorine-containing polyether hydrophilic modifier is 5%-30% of the mass of the polyisocyanate, and the reaction temperature is 80-85% ℃, the reaction time is 2.5-3-4h; then benzoyl chloride is added to terminate the reaction, and the mass of benzoyl chloride is 0.01-0.1% of the total mass of the reactants; the reaction is stopped to obtain a hydrophilic modified polyisocyanate curing agent; S2, in Under nitrogen protection, the aromatic polyisocyanate is added to the hydrophilic modified polyisocyanate curing agent, stirred and mixed for 5-40 minutes to obtain a water-dispersible polyisocyanate composition, wherein the hydrophilic modified polyisocyanate curing agent and the aromatic polyisocyanate are mixed. The mass ratio of isocyanate is 10:1 to 1:3.

As a preferred solution of the present invention, in step S2, the mass ratio of the hydrophilic modified polyisocyanate curing agent to the aromatic polyisocyanate is 5:1 to 1:1, and the kinetic viscosity of the prepared water-dispersible polyisocyanate composition is It is 4000 mPa.s or less, and the NCO content is 15 to 25% of the total mass.

It can be seen from the above technical solutions that the beneficial effects of the present invention are: the present invention utilizes the hydrophobicity of the fluorine-containing polyether segment in the composition to separate the zwitterion and the polyisocyanate, and the fluorine-containing ion having a strong hydrophobic effect is obtained. The polyether segment can effectively shield and protect the adjacent -NCO group, reducing the probability of the -NCO group contacting and reacting with water, thereby extending the pot life of the water-dispersible polyisocyanate and reducing the release of CO ₂ from the cured product The opportunity of gas can improve the performance of the two-component waterborne polyurethane cured product, endow the polyisocyanate composition with good emulsification, and make the polyisocyanate curing agent and various ionic types of waterborne resins including anionic, cationic and non-ionic. The curing system reduces the influence of pH value on the stability of the curing agent emulsion, and still maintains quite good emulsion stability in the presence of a certain concentration of acid, alkali and salt, and overcomes the water-dispersible polyisocyanate in the prior art. Short defects; the use of the hydrophilicity in the zwitterionic fragment in the composition makes the composition have good water dispersibility, and absorbs the advantages of amphoteric surfactants, for modifying polyisocyanates, using zwitterions The segment makes the composition have both hard water resistance, high-concentration electrolyte resistance and good emulsifying and dispersing properties, overcoming the defect of the limited application range of the anion-modified polyisocyanate curing agent; The reactive aromatic-NCO groups increase the composition's resistance to hard water, high electrolyte resistance, and good emulsifying and dispersing properties, and due to the tendency of highly reactive aromatic-NCO groups in aromatic polyisocyanates It is shielded and protected by the fluorine-containing polyether segment in the interior of the emulsion droplet, reducing the probability of the -NCO group contacting and reacting with water, thereby prolonging the pot life of the water-dispersible polyisocyanate, further overcoming the water-dispersible polyisocyanate in the prior art. The defects of short pot life of dispersed polyisocyanates, and the preparation cost of aromatic polyisocyanates are lower than the preparation cost of hydrophilic modified polyisocyanate curing agents, and the proportion of aromatic polyisocyanates to form compositions can effectively reduce the water dispersible polyisocyanates. Therefore, the defects of short pot life and high production cost of the water-dispersible polyisocyanate in the prior art are solved, and a low-cost and high-performance water-dispersible polyisocyanate composition is obtained.

Description of drawings

Fig. 1 is the hydrogen nuclear magnetic resonance spectrum analysis spectrum of polyether A prepared in Example 1 of the present invention.

FIG. 2 is the Fourier transform infrared spectrum of the polyether A prepared in Example 1 of the present invention.

Fig. 3 is the electrospray ionization mass spectrum of polyether A prepared in Example 1 of the present invention.

Fig. 4 is the nuclear magnetic resonance fluorine spectrum analysis spectrum of polyether B prepared in Example 1 of the present invention.

Fig. 5 is the nuclear magnetic resonance fluorine spectrum analysis spectrum of polyether C prepared in Example 2 of the present invention.

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

Detailed ways

The following examples are used to further illustrate the present invention in detail, but the examples do not limit the present invention in any form, unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field, But the present invention is not limited in any form.

A water-dispersible polyisocyanate composition, comprising a hydrophilic modified polyisocyanate curing agent and an aromatic polyisocyanate; wherein, the mass ratio of the hydrophilic modified polyisocyanate curing agent to the aromatic polyisocyanate is 10:1-1 : 3, and the NCO content is 15-25% of the total mass of the water-dispersible polyisocyanate composition, and the water-dispersible polyisocyanate composition contains a fluorine-containing polyether segment and a zwitterionic segment. The aromatic polyisocyanates are aromatic diisocyanates and trimer or multimer derivatives of aromatic diisocyanates. The aromatic polyisocyanates are toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, tetramethyl xylylene diisocyanate and polymeric diphenylmethane diisocyanate. one or more mixtures. More specifically, the aromatic polyisocyanate is hexamethylene diisocyanate. The mass ratio of the hydrophilic modified polyisocyanate curing agent to the aromatic polyisocyanate is 5:1-1:1, and the NCO content is 17-23% of the total mass of the water-dispersible polyisocyanate composition. The hydrophilic modified polyisocyanate curing agent is synthesized by reacting an aliphatic or alicyclic polyisocyanate with a fluorine-containing polyether hydrophilic modifier, and the mass of the fluorine-containing polyether hydrophilic modifier accounts for the hydrophilic 10.0 to 50.0% of the total mass of the modified polyisocyanate curing agent, and the molecular structure of the fluorine-containing polyether hydrophilic modifier is shown in formula A

Wherein, R _f is a fluorine-containing alkyl group; R is an alkyl group; x is an integer of 1-20; y is an integer of 1-20. R _f is specifically trifluoromethyl-CF ₃ , pentafluoroethyl-CH ₂ CF ₃ , tetrafluoropropyl-CH ₂ CF ₂ CF ₂ H, perfluorobutyl-(CF ₂ ) ₃ CF ₃ , perfluoro _Hexyl- ( _CF2 ) _5CF3 , perfluorooctyl-( _CF2 ) _7CF3 or perfluorohexylethyl _- CH2CH2( _{CF2 ) 5CF3 ; R} is specifically ethyl _- CH2CH _{3. propyl - CH2CH2CH3} or butyl _{- CH2CH2CH2CH3 ;} x is an integer _of 1-10; y is an integer of 1-10. The sulfoalkyl betaine group in the water-dispersible polyisocyanate composition accounts for 0.4-9.1% of the total mass; and the mass ratio of the fluorine-containing polyether hydrophilic modifier accounts for 2.5-45.5% of the total mass . The sulfoalkyl betaine group in the water-dispersible polyisocyanate composition accounts for 1.4-6.6% of the total mass, and the mass ratio of the fluorine-containing polyether hydrophilic modifier accounts for 10.0-33.3% of the total mass . The dynamic viscosity of this modified mixed polyisocyanate determined using a rotational viscometer is 4000 mPa.s or less, preferably 2000 mPa.s or less.

A preparation method of a water-dispersible polyisocyanate composition for preparing the water-dispersible polyisocyanate composition according to any one of claims 1-8, which is prepared as follows:

S1. Synthesis of hydrophilic modified polyisocyanate curing agent: firstly synthesize fluorine-containing polyether hydrophilic modifier; then under nitrogen protection, heat polyisocyanate to 70-100℃; then add fluorine-containing polyether hydrophilic modifier into the reactor The water modifier is reacted in the presence of the catalyst dibutyltin dilaurate, wherein the mass of the fluorine-containing polyether hydrophilic modifier is 5%-30% of the mass of the polyisocyanate, and the reaction temperature is 80-85% ℃, the reaction time is 2.5-3-4h; then benzoyl chloride is added to terminate the reaction, and the mass of the benzoyl chloride is 0.01-0.1% of the total mass of the reactants; the reaction is stopped to obtain a hydrophilic modified polyisocyanate curing agent.

In step S1, the synthesis process of the fluorine-containing polyether hydrophilic modifier is as follows:

S11. Synthesis of tertiary amino polyether monool: using propylene oxide as monomer and dialkylamine as starting agent, through anionic ring-opening polymerization to synthesize tertiary amino polyether with hydroxyl at one end and tertiary amino group at the other end Monohydric alcohol; wherein, the molar ratio of propylene oxide as monomer and dialkylamine is 2:1～30:1, preferably 2:1～20:1, more preferably 5:1～10:1; Step S11 The specific process is: S111, adopting dialkylamine as a starting agent and a metered propylene oxide in a ring-opening polymerization reaction in an autoclave; lowering the temperature when the autoclave is aged to normal pressure to obtain a tertiary amine-based polyether Crude monohydric alcohol. Wherein, the autoclave adopts nitrogen protection, and the molar ratio of propylene oxide as monomer and dialkylamine is 2:1～30:1, preferably 2:1～20:1, more preferably 5:1～10:1: 1; Potassium hydroxide KOH is selected as the catalyst, and the quality of the catalyst is 0.05%-2% of the monomer mass, preferably 0.1%-1%, more preferably 0.2%-0.5%. The initial reaction temperature is controlled at 100-150° C.; S112, adding equal mass of distilled water to the crude tertiary amino polyether monool and stirring. Then, 0.1 mol/L of dilute hydrochloric acid in an equimolar amount with catalyst KOH was added for neutralization. Finally, the water is removed by distillation under reduced pressure; S113, n-hexane is added as a water-carrying agent, and the quality of n-hexane is 0.5-2 times, preferably 1-1.5 times that of the polyether; and the tertiary amino polyether is further removed by distillation. Moisture in the monohydric alcohol crude product; S14, finally remove n-hexane by vacuum distillation to obtain refined tertiary amino polyether monohydric alcohol;

S12. Synthesis of zwitterionic polyether monool: adopt propane sultone to react with tertiary amino polyether monool to obtain zwitterionic polyether monool with zwitterionic group. The molar ratio of propane sultone to tertiary amino polyether monool is 1:1 to 1.5:1, preferably 1:1 to 1.1:1, more preferably 1:1 to 1.05:1; step S2 is specifically: : sulfopropylation of 1,3-propane sultone and tertiary amino polyether monool to prepare zwitterionic polyether monool with zwitterionic group; propane sultone and tertiary amino polyether The molar ratio of the monohydric alcohol is 1:1-1.5:1, preferably 1:1-1.1:1, more preferably 1:1-1.05:1;

S13. Synthesis of fluorine-containing polyether hydrophilic modifier: using zwitterionic polyether monoalcohol as the starting agent and fluorine-containing alkyl propylene oxide as the monomer, the fluorine-containing polyether segment is grafted by cationic ring-opening polymerization To the end of the zwitterionic polyether monool, a fluoropolyether hydrophilic modifier with zwitterionic groups is obtained. The mass ratio of the zwitterionic polyether monool to the fluorine-containing alkyl propylene oxide is 1:0.5 to 1:8, preferably 1:1 to 1:5, more preferably 1:1 to 1:3; the details of step S13 The process includes: S131, adding solvent dichloromethane, zwitterionic polyether monoalcohol with zwitterionic group, catalyst boron trifluoride ether complex and tetrabutylammonium bromide into the flask and stirring; solvent The mass of dichloromethane is 0.5-5 times the mass of the zwitterionic polyether monool, preferably 1-3 times, more preferably 1.5-2 times; the mass of the catalyst boron trifluoride ether complex is the zwitterionic polyether 0.1%-5% of monohydric alcohol, preferably 0.5%-5%, more preferably 0.5%-3%; the mass of catalyst tetrabutylammonium bromide is 0.1%-5% of zwitterionic polyether monohydric alcohol, preferably 1%-5%, more preferably 1%-3%. S132, the temperature in the flask is lowered to 0° C. with a low temperature constant temperature circulation tank, and after stirring for 20-30 min, the fluorine-containing alkyl propylene oxide is added dropwise. The mass ratio of the zwitterionic polyether monool to the fluorine-containing alkyl propylene oxide is 1:0.5-1:8, preferably 1:1-1:5, more preferably 1:1-1:3; maintain the temperature of the reaction system At -1°C to 1°C, the dropwise addition time is 2-3h. After the dropwise addition, keep the temperature unchanged and continue the reaction for 3-4h; S133, add 30ml of water under stirring to terminate the polymerization reaction; S134, pass The solvent and water were removed by distillation under reduced pressure to obtain the crude product of fluorine-containing zwitterionic polyether monool. Step S13 also includes: S135, adding the obtained crude fluorine-containing zwitterion polyether monoalcohol to an isopropanol solvent to dilute, and the quality of the isopropanol solvent is 0.5-5 times that of the crude fluorine-containing zwitterion polyether monool, preferably the mass It is 1-5, more preferably 1-2 times; S136, then add magnesium silicate adsorbent, and remove the salt and adsorbent precipitated in the crude fluorine-containing zwitterionic polyether monool through a filter press; magnesium silicate The mass of the adsorbent is 0.1-1 times, preferably 0.1-0.5 times, more preferably 0.1-0.3 times that of the fluorine-containing zwitterion polyether monool; S137, further use a strong acid cation exchange resin to process until the obtained fluorine-containing zwitterions are The alkali metal content in the crude polyether monoalcohol is reduced to less than 5ppm; S138, after removing the isopropanol solvent by vacuum distillation, a refined fluorine-containing zwitterionic polyether monool is obtained, that is, a fluorine-containing polyether hydrophilic modification is obtained. Sexual agent. The hydrophobic fluoropolyether segment and the hydrophilic zwitterion segment are linked together with the hydrophilically modified polyisocyanate in the fluoropolyether hydrophilic modifier. The polyisocyanates in the fluorine-containing polyether hydrophilic modifier are based on aliphatic or alicyclic polyisocyanates, and these polyisocyanates may include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) ), 4,4'-dicyclohexylmethane diisocyanate (H12MDI), cyclohexane diisocyanate (CHDI) and 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI) Trimeric derivatives of aliphatic or cycloaliphatic diisocyanates, preferably trimers of HDI.

S2, under nitrogen protection, add the aromatic polyisocyanate to the hydrophilic modified polyisocyanate curing agent, stir and mix for 5-40min to obtain a water-dispersible polyisocyanate composition, wherein the hydrophilic modified polyisocyanate curing agent and The mass ratio of the aromatic polyisocyanate is 10:1 to 1:3. In step S2, the mass ratio of the hydrophilic modified polyisocyanate curing agent to the aromatic polyisocyanate is 5:1 to 1:1, the kinetic viscosity of the prepared water-dispersible polyisocyanate composition is below 4000 mPa.s, and the NCO The content is 15-25% of the total mass.

Below in conjunction with embodiment, the present invention is further described:

Synthesis of Fluoropolyether Hydrophilic Modifier:

Example 1

As shown in Figure 1-4, the ring-opening polymerization of propylene oxide is catalyzed by using diethylamine as the initiator and KOH as the catalyst. The synthesis was carried out in a clean and dry 1 L autoclave with stirring. First, 2.8 g of KOH catalyst was placed in the autoclave, and then the autoclave was repeatedly evacuated and filled with nitrogen. Then, 111.0 g (~1.52 eq) of chromatographically pure grade (purity ≥99.5%) diethylamine was added to the kettle at room temperature as a starting agent to synthesize monofunctional polyether. At room temperature, 3.6 bar of nitrogen was introduced. Then, 40 g of propylene oxide was pressed in, and the temperature of the reactor was gradually raised to 125° C. for induction reaction. When the reaction pressure drops suddenly and the temperature rises above 5°C, the induction reaction ends. 426 g of propylene oxide were gradually added to the autoclave over the next 3 hours and 30 minutes. The mixture was stirred and reacted for 50 minutes. The tertiary aminopolyether monool was collected by filtration at 105°C and 10 mbar. The reaction formula is shown in (1):

Transfer 571 g (~1.52 eq) of the tertiary amine-based polyether sample prepared above into a 1000 ml four-neck flask, and remove residual small molecules under reduced pressure at a temperature of 80°C. Then, 100 ml of HCl solution with a concentration of 0.5 mol/L was added to neutralize catalyst KOH, and the aqueous layer was separated after standing. Under nitrogen protection, the reacted mixture was distilled under reduced pressure to remove moisture to obtain tertiary amino polyether monool.

Take 131.6g (~0.35eq) of the tertiary amine-based polyether sample prepared above and put it in a 500ml three-necked flask, add 42.8g (~0.35eq) of 1,3-propane sultone and 100ml of acetone to the reaction flask, The reaction was heated and refluxed for 24 hours under stirring, and the reaction was shown in formula (2). Lower the temperature to stop the reaction. The acetone solvent was removed by distillation under reduced pressure to obtain a sample of zwitterionic polyether monool, denoted as polyether A.

The obtained polyether A was tested for physical properties, and it was found that its hydroxyl value was 112.36 mg KOH/g, and its viscosity was 450 mPa.s. Polyether A was analyzed by hydrogen nuclear magnetic resonance ( ¹ H-NMR), as shown in Figure 1:

According to the intensity of the NMR absorption peak and the chemical shift of the absorption peak, the chemical structures corresponding to each absorption peak af in Figure 1 are determined as: a:δ=3.25-3.79ppm(m, -O CH ₂ CH (CH ₃ )- and -CH ₂ CH ₂ CH ₂ -SO ₃ ^- ); b: δ = 3.12-3.19ppm (t, -CH ₂ CH ₂ CH ₂ -SO ₃ ^- ); c: δ = 2.85-3.08ppm (m, -OCH ₂ CH (CH ₃ )-N ⁺ (CH ₂ CH ₃ ) ₂ - and -N ⁺ ( CH ₂ CH ₃ ) ₂ -); d: δ=2.65(s,-OH); e: δ=2.10-2.21ppm ( m, -CH ₂ CH ₂ CH ₂ -SO ₃ ^- ); f: δ = 1.55-1.61 ppm (m, -N ⁺ (CH ₂ CH ₃ ) ₂ - ); g: δ = 0.96-1.20 ppm (m, -OCH2CH( _CH3 ) _- and -OCH2CH( _{CH3 )} -N ⁺ ( _{CH2CH3 ) 2-} ). H NMR spectrum further proved the existence of a large number of polyether chains in the product, and the absorption peaks b and e indicated the presence of propanesulfonyl groups in the product.

The synthesized product A was characterized by Fourier transform infrared spectroscopy (FT-IR), as shown in Figure 2. Among them, the strong absorption peak at 3455.5cm ^-1 is the OH stretching vibration peak of hydroxyl; the absorption peaks at 2989cm ^-1 and 2882cm ^-1 are -CH ₃ asymmetric stretching vibration and -CH ₂ -symmetric stretching vibration absorption peak; 1476cm The peak at ^-1 is -CH ₂ -scissor vibration or -CH ₃ antisymmetric vibration absorption peak; the absorption peak at 1356cm ^-1 is -CH ₂ - deformation vibration peak; the peak at 1230cm ^-1 is the symmetry of -SO ₃ - Stretching vibration absorption peak; 1112cm ^-1 is the asymmetric stretching vibration absorption peak of ether bond COC; 1038cm ^-1 peak is CN stretching vibration absorption peak, 620.3cm ^-1 peak SO bond stretching vibration absorption peak. This shows that there are hydroxyl groups, ether bonds and sulfonic acid groups in the product, which conforms to the structural characteristics of polyether A.

The synthesized product A was characterized by electrospray ionization mass spectrometry (ESI-MS), see Figure 3 . The difference between the two adjacent molecular ion peaks is about 58, which is exactly equal to the molecular weight of propylene oxide, indicating that the molecules are a mixture of different molecular weights obtained by the polymerization of propylene oxide. The m/z value of each molecular ion peak is also close to the molecular structure of polyether A. In addition, the highest relative abundance of the molecular ion peak appears in the m/z=426-542 range, and the actual measured hydroxyl value is 112.36 mg KOH/g. According to the fact that each polyether molecule contains a hydroxyl group, it can be The calculated theoretical average molecular weight of the zwitterionic polyether is 498.4 g/mol, which is in this range. The results of comprehensive analysis of mass spectrometry, infrared and nuclear magnetic resonance showed that the structure of product A was the zwitterionic polyether shown in the reaction formula (2).

Add 60 g of dry dichloromethane solvent, 40 g of polyether A (as an initiator), 0.8 g of tetrabutylammonium bromide, and 1.2 g of boron trifluoride ether (as a catalyst) into three ports equipped with a stirrer and a thermometer. flask, start stirring. Use a refrigerator to reduce the temperature of the reaction system to about 0 °C, and after stirring for 20-30 min, 38 g of 3-(2,2,3,3-tetrafluoropropoxy)-1,2-epoxypropane was added dropwise. The temperature of the reaction system was maintained at about 0°C, and the dropwise addition time was about 2h. After the dropwise addition, the reaction was continued for 3 h while keeping the temperature unchanged. Then, 200 g of water was added and stirred for 5 min to destroy the catalyst and terminate the polymerization reaction. The water-insoluble oil phase was removed, and then it was distilled under reduced pressure to obtain a fluorine-containing polyether monool, denoted as polyether B. The obtained fluorine-containing polyether monool was vacuum-dehydrated for 1 hour, and then sealed and stored. The reaction formula is shown in (3):

Take polyether B and add 100ml of isopropanol to dilute, then add a certain amount of 30g magnesium silicate adsorbent, stir evenly, and then let stand for 2-3 hours. The adsorbents and salts in the polyether were removed by a plate and frame filter press, and then the isopropanol was removed by distillation under reduced pressure. The polyether B was further treated with strong acid cation exchange resin (model 001×7) until the content of potassium ion K ⁺ and sodium ion Na ⁺ in the polyether was below 5 ppm. Fluorine nuclear magnetic resonance spectroscopy ( ¹⁹ F-NMR) was performed on polyether B, as shown in FIG. 4 . According to the intensity of the NMR absorption peak and the chemical shift of the absorption peak, the chemical structures corresponding to the absorption peaks of a and b in Fig. 4 are determined as follows: a: δ=-128, 17ppm(s, -CF ₂ -); b: δ=- 128, 17 ppm (d, _-CF2H ). Nuclear magnetic resonance fluoride spectrum shows that polyether B is a fluorine-containing zwitterionic polyether in accordance with the reaction formula (3). The physical properties of the obtained polyether B were tested, and the properties of the obtained polyether B were as follows:

The hydroxyl value of polyether B: 58.75mg KOH/g;

Viscosity of polyether B: 470mPa.s;

K ⁺ +Na ⁺ content: 5ppm.

Example 2

As shown in Figure 5, using polyether A as a raw material, 85 g of dry dichloromethane solvent, 40 g of polyether A (as an initiator), 1.1 g of tetrabutylammonium bromide, 1.2 g of boron trifluoride ether ( as a catalyst) was added to a three-necked flask equipped with a stirrer and a thermometer, and stirring was started. The temperature of the reaction system was lowered to about 0°C with a refrigerator, and after stirring for 20-30min, 72g of 3-(2-perfluorohexylethoxy)-1,2-epoxypropane was added dropwise, and the temperature of the reaction system was maintained at At about 0°C, the dropwise addition time is about 2h. After the dropwise addition, the reaction was continued for 3 h while keeping the temperature unchanged. Then, 200 g of water was added and stirred for 5 min to destroy the catalyst and terminate the polymerization reaction. The water-insoluble oil phase was removed, and then it was distilled under reduced pressure to obtain a fluorine-containing polyether monool, denoted as polyether C. The obtained fluorine-containing polyether monool was vacuum-dehydrated for 1 hour, and then sealed and stored. The reaction formula is shown in (4):

Fluorine nuclear magnetic resonance spectroscopy ( ¹⁹ F-NMR) was performed on polyether C, as shown in FIG. 5 . According to the intensity of the NMR absorption peak and the chemical shift of the absorption peak, the chemical structure corresponding to each absorption peak af in Figure 4 is determined as: a: δ=-80.85ppm (s, -CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ ) ; b: δ = -114.29ppm (s, -CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ ); c: δ = -121.91 ppm (s, -CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ ) ; d: δ = -122.85ppm (s, -CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ ); e: δ = -123.51 ppm (s, -CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ ) ; f: δ = -126.16 ppm (s, -CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ ). Nuclear magnetic resonance fluoride spectrum shows that polyether C is a fluorine-containing zwitterionic polyether in accordance with the reaction formula (4). The physical properties of the obtained polyether C were tested, and the properties were obtained as follows:

The hydroxyl value of polyether C: 41.23mg KOH/g;

Viscosity of polyether C: 480mPa.s;

K ⁺ +Na ⁺ content: 5ppm.

Synthesis of hydrophilic modified polyisocyanate curing agent:

Example 3

A trimer (HDT) product of hexamethylene diisocyanate (HDI) was used as the polyisocyanate matrix. The viscosity of the polyisocyanate was 1400 mPa.s and the NCO group content was 23.1%. 300g (NCO group content ~ 1.65eq) polyisocyanate was placed in a 500ml four-necked flask, and 0.5g of dibutyltin laurate was added as a catalyst. The flask was protected with dry nitrogen gas, the reaction was heated to 80° C., a certain amount of polyether B (see Table 1) was added dropwise under stirring, and the dropwise addition was completed within 30 min. The reaction was continued for 2 hours, and when the content of -NCO group reached 18.6%, 0.2 g of benzoyl chloride was added to stop the reaction to obtain a colorless or light yellow transparent viscous product. The theoretical value of the -NCO group content after hydrophilic modification is calculated by using the amount of hydrophilic modified polyether and its hydroxyl value. Taking Example 3 as an example, the hydroxyl value of the hydrophilic modifier polyether B is 58.75 mg KOH/g, and its theoretical molecular weight is 953 g/mol. Assuming that the total amount of polyisocyanate and polyether is 100 g, the amount of polyisocyanate when 11.36% of polyether B is used as the hydrophilic modifier is 88.64 g, and the amount of polyether B is 11.36 g. The amount of -NCO group consumed by the polyether is (11.36g×58.75×10 ^-3 )/56.1g/mole×42.02g=0.5g, then the theoretical value of the -NCO group after the hydrophilic reaction is (88.64g ×0.231-0.5g)/100g=19.97%.

Synthesis of Hydrophilic Modified Polyisocyanate Composition:

Example 4

150 g of the polyisocyanate prepared in Example 3 was placed in a three-necked flask with stirring, and dry nitrogen was introduced. Under nitrogen protection, 75 g of tetramethylxylylene diisocyanate (TMXDI) was added, and the mixture was stirred and mixed for 15 minutes at room temperature to obtain a hydrophilic modified polyisocyanate composition.

Example 5

Carry out the same operation as in Example 4 under the same conditions, add 60 g of tetramethylxylylene diisocyanate (TMXDI) under nitrogen protection, and stir and mix at room temperature for 15 min to obtain a hydrophilic modified polyisocyanate combination.

Example 6

Carry out the same operation as in Example 4 under the same conditions, add 45 g of tetramethylxylylene diisocyanate (TMXDI) under nitrogen protection, and stir and mix for 15 min at room temperature to obtain a hydrophilic modified polyisocyanate combination thing.

Example 7

The same polyisocyanate as in Example 3 was used as the matrix. 600g (NCO group content ~ 1.65eq) polyisocyanate was placed in a 1000ml four-necked flask, and 0.5g of dibutyltin laurate was added as a catalyst. The flask was protected with dry nitrogen gas, the reaction was heated to 80° C., 168 g of polyether C was added dropwise under stirring, and the dropwise addition was completed within 30 min. The reaction was continued for 2 hours, and when the content of the -NCO group reached 17.4%, 0.2 g of benzoyl chloride was added to stop the reaction to obtain a colorless, transparent and viscous product.

Example 8

150 g of the polyisocyanate prepared in Example 7 was placed in a three-necked flask with stirring, and dry nitrogen was introduced. Under nitrogen protection, 75 g of polymeric diphenylmethane diisocyanate (PAPI) was added, and the mixture was stirred and mixed for 15 minutes at room temperature to obtain a hydrophilic modified polyisocyanate composition.

Example 9

The same operation as in Example 4 was carried out under the same conditions, and 60 g of polymeric diphenylmethane diisocyanate (PAPI) was added under nitrogen protection, and stirred and mixed at room temperature for 15 min to obtain a hydrophilic modified polyisocyanate composition.

Example 10

Under the same conditions, carry out the same operation as in Example 4, add 45 g of polymeric diphenylmethane diisocyanate (PAPI) under nitrogen protection, and stir and mix for 15 min at room temperature to obtain a hydrophilic modified polyisocyanate composition.

Example 11 (comparative example)

Using 3-(cyclohexylamino)-1-propanesulfonic acid (CAPS), N,N-dimethylcyclohexylamine and the same polyisocyanates as those in Examples 4 to 12 above as raw materials to synthesize anion-modified polyisocyanates for curing agent. Put 180g (~1.10eq) polyisocyanate in a 500ml four-necked flask, add 80ml propylene glycol methyl ether acetate (PMA) as a solvent, then add 5.6g CAPS and 3.2g N,N-dimethylcyclohexylamine, using 0.5 g of dibutyltin laurate was used as catalyst. The flask was protected with dry nitrogen gas, and the reaction was heated to 80 °C for 4 h to obtain a colorless and transparent solution. The solvent was distilled off under reduced pressure to obtain a colorless transparent viscous liquid, and the sample was recorded as Control.

Performance Evaluation of Hydrophilic Modified Polyisocyanate Curing Agent: Water Dispersion Test

At room temperature, take 10 g of the hydrophilically modified polyisocyanate composition, disperse it in 50 ml of deionized water, disperse the mixture at 800 rpm for 10 min with a high-speed dispersing machine, let stand for 10 min, and visually observe the state of the aqueous dispersion , the dispersion state is evaluated according to the following criteria:

×----- There are always oil droplets and micelles, which cannot be dispersed evenly;

Δ------ can be uniformly dispersed, but appears white and turbid;

√------Evenly dispersed to form a fine emulsion, slightly transparent.

The pot life of the polyisocyanate dispersed in water was determined by tracking the -NCO content of the polyisocyanate titrated in water. From the time of dispersing into water, the time when the -NCO content of polyisocyanate drops sharply is defined as the pot life of its dispersing in water.

Formulation of two-component waterborne polyurethane coating (2K-WPU):

The hydroxyl acrylic emulsion Bayhydrol XP 2546 of Bayer Company was used as the anionic hydroxyl emulsion, and 120g Bayhydrol XP 2546 was mixed with 30g Control and the series of water-dispersible polyisocyanate curing agents synthesized in Examples 4-6 and 8-10 respectively to form 2K-WPU coating. Similarly, 160 g of the cationic polyurethane emulsion synthesized in Example 11 was mixed with 25 g of the above water-dispersible polyisocyanate curing agent to form a 2K-WPU coating. Observing the state of the emulsion after mixing and dispersing, evaluate the state of the 2K-WPU coating according to the following criteria:

×-----agglomeration occurs and a stable emulsion cannot be formed;

√------Can form stable 2K-WPU emulsion.

Test 2K-WPU paint viscosity and pot life. The pot life of 2K-WPU coating is determined by the gloss of the coating film, because after 2K-WPU is placed beyond its pot life, its mechanical properties and film gloss will change greatly. - The WPU paint is brushed on the tinplate sheet, and the 60o angle gloss of all the coating samples is measured, and the storage time corresponding to the sample whose gloss is obviously decreased is determined as the pot life of 2K-WPU. Coat the 2K-WPU coating on the polytetrafluoroethylene mold to form a film, and remove it after drying. Take a 5cm×5cm coating film and weigh it as m0, put it in distilled water for 24 hours, take it out and weigh it as m0, and calculate water absorption = (m1-m0)/m0.

As can be seen from Table 1, the modified aliphatic polyisocyanate and aromatic polyisocyanate compositions exhibited good water dispersibility. Moreover, in the polyisocyanate composition composed of polyether B-modified aliphatic polyisocyanate and TMXDI, the pot life of dispersing in water was 3-3.5 hours, while in polyether C-modified aliphatic polyisocyanate and PAPI, the pot life was 3-3.5 hours. The pot life of the isocyanate composition dispersed in water is 2.5-3 hours, which may be mainly because the reactivity of PAPI to water is greater than that of TMXDI, so that the pot life is shortened. However, the pot life of the polyisocyanates obtained in Examples 4-6 and 8-10 is similar to that of anion-modified aliphatic polyisocyanates. From the point of view of their process performance, these aromatic-containing hydrophilic modified Polyisocyanates can be used as water-dispersible polyisocyanate curing agents. The reason why the polyisocyanate composition containing aromatic polyisocyanate shows good process performance is mainly because the fluorine-containing polyether segment of the prepared hydrophilic modifier provides protection for the -NCO group. In addition, aromatic polyisocyanates only account for a certain proportion in the mixed polyisocyanates, while aliphatic polyisocyanates account for a large proportion, so that the pot life of the mixed polyisocyanates is improved.

As can be seen from Table 2, after forming 2K-WPU with anionic emulsion, the pot life of the polyisocyanates obtained in Examples 4-6 and 8-10 is similar to the anion-modified aliphatic polyisocyanate sample Control. At the same time, the 2K-WPU coatings prepared with the polyisocyanates obtained in Examples 4-6 and 8-10 exhibited higher hardness compared with the anion-modified aliphatic polyisocyanates. This is mainly because there are aromatic polyisocyanates in Examples 4-6 and 8-10, and the mechanical properties of their cured products are better than those of aliphatic polyisocyanates. In addition, compared with the sample Control, the modified polyisocyanates obtained in Examples 4-6 and 8-10 have a higher content of -NCO groups, which increases the crosslinking density of the cured products, thus showing higher hardness. Compared with the sample Control, the 2K-WPU coatings prepared from the modified polyisocyanates obtained in Examples 4-6 and 8-10 exhibited lower water absorption. This is mainly due to its higher crosslinking density, and the introduction of fluorine-containing polyether segments into the components of the curing agent, which plays a hydrophobic role, thereby showing higher water resistance.

Table 1. Hydrophilic Modified Polyisocyanate Curing Agent Properties

*Modifier mass: refers to the mass percentage of hydrophilic modifier in the total polyisocyanate and hydrophilic modifier.

**-NCO (%): refers to the -NCO group content measured after the reaction was placed at room temperature for 3 days.

Table 2. Two-component waterborne polyurethane coating 2K-WPU

A kind of modified aliphatic polyisocyanate and aromatic polyisocyanate disclosed in the present invention has special formula composition and special molecular structure of fluorine-containing polyether hydrophilic modifier, so that aromatic polyisocyanate can be used as water-dispersible polyisocyanate. Components of polyisocyanates. The cost of water-dispersible polyisocyanates is reduced and the mechanical properties are improved due to the use of aromatic polyisocyanates. In addition, due to the presence of the fluoropolyether structure in the modifier, the water resistance of the cured coating film is improved.

Obviously, in the water-dispersible polyisocyanate composition provided by the present invention, aliphatic polyisocyanate is used as the hydrophilic modification component, and when the water-dispersible polyisocyanate composition is dispersed in water, these bonded hydrophilic The aliphatic polyisocyanates of the modifier tend to be in the outer layers of the emulsion droplets, while the aromatic polyisocyanates tend to be in the interior of the emulsion droplets. The highly reactive aromatic-NCO groups can be protected by the less reactive aliphatic polyisocyanates. The fluoropolyether segment on the hydrophilic modifier also provides protection to the -NCO groups inside the emulsion droplets. Therefore, in the present invention, the aromatic polyisocyanate can be used as a constituent of the water-dispersible polyisocyanate, thereby reducing the cost of the water-dispersible polyisocyanate. Since aromatic polyisocyanate can be used in the water-dispersible polyisocyanate composition provided by the present invention, the mechanical properties of the cured product can be improved. As a cross-linking agent for water-based polymers, polyisocyanates achieve water dispersibility by introducing zwitterionic fragments as hydrophilic groups, while water-based resins often introduce zwitterionic fragments as hydrophilic groups in the molecular structure or use Surfactant, which makes the cured product of the two-component waterborne polyurethane system composed of water-dispersible polyisocyanate as the cross-linking agent often have the problem of poor water resistance. In the present invention, the water resistance of the cured product of the two-component aqueous polyurethane system can be improved by introducing the hydrophobic fluorine-containing polyether segment into the modifier. The entire composition can be viewed as a zwitterionic fragment of a zwitterionic surfactant with hydroxyl groups, wherein the sulfoalkylbetaine group is the hydrophilic zwitterionic fragment, and the fluoropolyether is the hydrophobic segment. Modification with this hydrophilic modifier can make the polyisocyanate curing agent obtain good water dispersibility. Compared with the existing anion-modified water-dispersible polyisocyanates on the market, the composition of this fluorine-containing zwitterionic polyether monool modifier not only imparts good emulsifying properties to the polyisocyanate composition, but also enables the polyisocyanate curing agent. It forms a curing system with water-based resins of various ionic types including anionic, cationic and non-ionic. It can reduce the influence of pH value on the stability of the curing agent emulsion, and still maintain a fairly good emulsion stability in the presence of a certain concentration of acid, alkali and salt. This is because the hydrophilic group of the zwitterionic fragment has both anionic and cationic moieties, showing isoelectric properties in solution. It has many excellent properties: including excellent resistance to hard water and high concentration of electrolytes, compatibility with various types of surfactants, and good emulsifying and dispersing properties. Therefore, the present invention absorbs the advantages of amphoteric surfactants and is used to modify polyisocyanates, and overcomes the shortcoming of limited application range of anionic modified polyisocyanate curing agents. And using the composition of the fluorine-containing zwitterionic polyether monool modifier can improve the pot life of the polyisocyanate curing agent. When the polyisocyanate composition using the anionic modifier is dispersed in water, the modified polyisocyanate is located at the outermost periphery of the emulsion droplets, and the anions face the water phase. However, the hydrophilic anion is directly connected to the polyisocyanate, which causes the -NCO group to easily come into contact with water and react, reducing the pot life of the curing agent, and generating carbon dioxide gas at the same time. The fluorine-containing polyether segment in the present invention separates the zwitterion from the polyisocyanate, and the fluorine-containing polyether segment with a strong hydrophobic effect can effectively shield and protect the adjacent -NCO group, reduce the -NCO group The probability of the group contacting and reacting with water, thereby extending the pot life of the water-dispersible polyisocyanate, reducing the chance of the cured product releasing CO2 gas, and improving the performance of the two-component waterborne polyurethane cured product.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the points that are different from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The above description of the disclosed embodiments enables those skilled in the art to practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. a water-dispersible polyisocyanate composition, is characterized in that, comprises hydrophilic modified polyisocyanate curing agent and aromatic polyisocyanate; Wherein, the mass ratio of hydrophilic modified polyisocyanate curing agent and aromatic polyisocyanate is is 10:1 to 1:3, and the NCO content is 15 to 25% of the total mass of the water-dispersible polyisocyanate composition, and the water-dispersible polyisocyanate composition contains a fluorine-containing polyether segment and a zwitterionic segment; The hydrophilic modified polyisocyanate curing agent is synthesized by reacting an aliphatic or alicyclic polyisocyanate with a fluorine-containing polyether hydrophilic modifier, and the mass of the fluorine-containing polyether hydrophilic modifier accounts for the hydrophilic 10.0 to 50.0% of the total mass of the modified polyisocyanate curing agent, and the molecular structure of the fluorine-containing polyether hydrophilic modifier is shown in formula A

Wherein, R _f is a fluorine-containing alkyl group; R is an alkyl group; x is an integer of 1-20; y is an integer of 1-20. 2 . The water-dispersible polyisocyanate composition according to claim 1 , wherein the aromatic polyisocyanate is an aromatic diisocyanate and a polymer derivative of the aromatic diisocyanate. 3 . 3. a kind of water-dispersible polyisocyanate composition according to claim 1, is characterized in that, described aromatic polyisocyanate is toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene A mixture of one or more of diisocyanate, tetramethylxylylene diisocyanate, and polymeric diphenylmethane diisocyanate. 4. a kind of water-dispersible polyisocyanate composition according to claim 1, is characterized in that, the mass ratio of described hydrophilic modified polyisocyanate curing agent and aromatic polyisocyanate is 5:1～1:1, The NCO content is 17-23% of the total mass of the water-dispersible polyisocyanate composition. 5. a kind of water-dispersible polyisocyanate composition according to claim 1, is characterized in that, R _f is specifically trifluoromethyl-CF ₃ , pentafluoroethyl-CF ₂ CF ₃ , tetrafluoropropyl-CH ₂ CF ₂ CF ₂ H, perfluorobutyl-(CF ₂ ) ₃ CF ₃ , perfluoro _Hexyl- ( _CF2 ) _5CF3 , perfluorooctyl-( _CF2 ) _7CF3 or perfluorohexylethyl _- CH2CH2( _{CF2 ) 5CF3 ; R} is specifically ethyl _- CH2CH _{3. propyl - CH2CH2CH3} or butyl _{- CH2CH2CH2CH3 ;} x is an integer _of 1-10; y is an integer of 1-10. 6. A water-dispersible polyisocyanate composition according to claim 5, wherein the sulfoalkyl betaine group in the water-dispersible polyisocyanate composition accounts for 0.4-9.1% of the total mass, And the mass ratio of the fluorine-containing polyether hydrophilic modifier accounts for 2.5-45.5% of the total mass. 7. A water-dispersible polyisocyanate composition according to claim 6, wherein the sulfoalkyl betaine group in the water-dispersible polyisocyanate composition accounts for 1.4-6.6% of the total mass, And the mass ratio of the fluorine-containing polyether hydrophilic modifier accounts for 10.0-33.3% of the total mass. 8. the preparation method of a water-dispersible polyisocyanate composition, is characterized in that, for preparing the water-dispersible polyisocyanate composition described in any one of claim 1-3, it is prepared like this: S1. Synthesis of hydrophilic modified polyisocyanate curing agent: firstly synthesize fluorine-containing polyether hydrophilic modifier; then under nitrogen protection, heat polyisocyanate to 70-100℃; then add fluorine-containing polyether hydrophilic modifier into the reactor The water modifier is reacted in the presence of the catalyst dibutyltin dilaurate, wherein the mass of the fluorine-containing polyether hydrophilic modifier is 5%-30% of the mass of the polyisocyanate, and the reaction temperature is 80-85% ℃, the reaction time is 2.5-3-4h; then benzoyl chloride is added to terminate the reaction, and the mass of the benzoyl chloride is 0.01-0.1% of the total mass of the reactants; the reaction is stopped to obtain a hydrophilic modified polyisocyanate curing agent; S2, under nitrogen protection, add the aromatic polyisocyanate to the hydrophilic modified polyisocyanate curing agent, stir and mix for 5-40min to obtain a water-dispersible polyisocyanate composition, wherein the hydrophilic modified polyisocyanate curing agent and The mass ratio of the aromatic polyisocyanate is 10:1 to 1:3. 9. the preparation method of a kind of water-dispersible polyisocyanate composition according to claim 8, is characterized in that, in step S2, the mass ratio of hydrophilic modified polyisocyanate curing agent and aromatic polyisocyanate is 5:1～ 1:1, the dynamic viscosity of the prepared water-dispersible polyisocyanate composition is below 4000 mPa.s, and the NCO content is 15-25% of the total mass.

Images