阅读说明：本技术 一种亲水性二异氰酸酯及其制备方法和应用 (Hydrophilic diisocyanate and preparation method and application thereof ) 是由 刘晓鸿 周国豪 梁杰宏 何绍群 周建明 于 2020-03-20 设计创作，主要内容包括：本发明属于聚氨酯领域,本发明提供一种亲水性二异氰酸酯,其包含至少一种含有如下通式的结构单元：<Image he="149" wi="700" file="DDA0002419452740000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>式中：SO<Sub>3</Sub>M为磺酸盐基团,M为K离子或Na离子或铵离子；n为1-6；所述亲水性二异氰酸酯是由至少一种亲水扩链剂与二异氰酸酯反应而生成。本发明的亲水性二异氰酸酯结构中的磺酸盐基是强酸强碱盐,具有很好的亲水性,两端头的异氰酸酯基保留了原二异氰酸酯的性能,因此具有二异氰酸酯的化学反应特性；且使用本发明亲水性二异氰酸酯制备水性聚氨酯改变了现有的工艺方法,极大地简化了操作。(The present invention belongs to polyurethaneIn the field, the present invention provides a hydrophilic diisocyanate comprising at least one structural unit having the formula: in the formula: SO (SO) 3 M is a sulfonate group, M is a K ion or a Na ion or an ammonium ion; n is 1 to 6; the hydrophilic diisocyanate is formed by reacting at least one hydrophilic chain extender with a diisocyanate. The sulfonate group in the structure of the hydrophilic diisocyanate is strong acid strong alkali salt, has good hydrophilicity, and the isocyanate groups at two ends retain the performance of the original diisocyanate, so the hydrophilic diisocyanate has the chemical reaction characteristic of the diisocyanate; the preparation of the waterborne polyurethane by using the hydrophilic diisocyanate changes the prior process method and greatly simplifies the operation.)

1. A hydrophilic diisocyanate comprising structural units of the general formula:

in the formula: SO (SO)₃M is sulfonate group, M is K ion or Na ion or ammonium ion, and n is 1-6.

2. The method for preparing a hydrophilic diisocyanate according to claim 1, comprising the steps of: and mixing and reacting diisocyanate with a hydrophilic chain extender to obtain the hydrophilic diisocyanate.

3. The production method according to claim 2, wherein the molar ratio of the diisocyanate to the hydrophilic chain extender is (2-6): 1; the hydrophilic chain extender is a micromolecular dihydric alcohol at least containing a sulfonate group-containing micromolecular dihydric alcohol or an amino sulfonate group-containing micromolecular dihydric alcohol; the diisocyanate is at least one of MDI, HMDI, TDI, HDI, IPDI or XDI.

4. The preparation method according to claim 2, characterized by comprising the following steps: adding diisocyanate and cosolvent into a reaction kettle, starting a stirrer, heating to 30-80 ℃, adding the hydrophilic chain extender in several times, reacting at 50-60 ℃ for 0.5-3 hours after adding the hydrophilic chain extender each time until the hydrophilic chain extender is added in the last time, reacting at 50-60 ℃ for 0.5-3 hours, heating to 60-80 ℃ again for 6-20 hours, cooling and discharging to obtain the hydrophilic diisocyanate.

5. The preparation method of claim 4, wherein the cosolvent is added in an amount of 0-40% by weight of the diisocyanate; the micromolecular dihydric alcohol containing sulfonate group is at least one of 1, 2-dihydroxy-3-propanesulfonic acid sodium salt, 1, 4-dihydroxy butane-2-sodium sulfonate or micromolecular sulfonate dihydric alcohol; the micromolecular sulfonate dihydric alcohol is prepared by esterification reaction of dicarboxyl sulfonate, micromolecular dihydric alcohol and micromolecular dibasic acid; the dicarboxyl sulfonate is at least one of dicarboxyl sodium sulfonate, dicarboxyl potassium sulfonate or dicarboxyl ammonium sulfonate; the molecular weight of the micromolecular sulfonate dihydric alcohol is 350-3000, the micromolecular dihydric alcohol is dihydric alcohol with the molecular weight of less than 300, and the micromolecular dibasic acid is dibasic acid with the molecular weight of less than 300.

6. The method according to claim 4, wherein the small molecule diol of the aminosulfonate group is sodium N, N-bis (2-hydroxyethyl) -2-aminoethanesulfonate.

7. The polyurethane emulsion is characterized by being prepared by the following preparation method: reacting the hydrophilic diisocyanate of claim 1 with a dihydroxy compound to obtain an aqueous polyurethane resin with a hydroxyl group at the end, and adding water to emulsify and disperse to obtain a polyurethane emulsion; the dihydroxy compound is at least one of polyester diol, polyether diol, polycaprolactone diol, hydroxyl-terminated alkyd resin, hydroxyl-terminated organic silicon resin, polyacrylic resin with hydroxyl or diol with the molecular weight less than 300.

8. A water-based polyurethane curing agent, which is prepared by reacting the hydrophilic diisocyanate according to claim 1 with a polyol.

9. A blocked aqueous polyisocyanate curing agent, which is obtained by reacting the aqueous polyurethane curing agent of claim 8 with a blocking agent.

10. Use of the hydrophilic diisocyanate of claim 1 in the preparation of an aqueous polyurethane coating, an aqueous polyurethane adhesive, an aqueous polyurethane vehicle, an aqueous leather finishing agent, an aqueous textile finishing agent, or an aqueous ink vehicle.

Technical Field

The invention belongs to the field of polyurethane, and particularly relates to hydrophilic diisocyanate and a preparation method and application thereof.

Background

The limit of environmental regulations on the discharge amount of Volatile Organic Compounds (VOCs) in chemical products promotes the development and application of waterborne polyurethane products, but some bottleneck technical problems still remain to be solved, such as: the hydrophilic raw materials required by the polyurethane hydration are too few in variety, the hydrophilic raw materials of the amino sulfonate are expensive, the hydrophilic raw materials of the dimethylolcarboxylic acid can react with isocyanate only by being dissolved by a special solvent, the processing technology is complex and the like, and the transformation of a polyurethane product of related enterprises from a solvent type to the hydration (changing oil into water) is restricted.

The water-based polyurethane is a water-based polyurethane product which is characterized in that hydrophilic groups are introduced into a hydrophobic polyurethane structure, and how to introduce hydrophilic groups with low price, no toxicity, no odor and good hydrophilic effect is achieved by adopting a simple and easy technological method, so that the main performance of the original solvent-based product is not changed, and no VOC is discharged, which is the key point of continuous research in the field.

The hydrophilic agent with better water changing effect of the polyurethane oil is sulfonate base at present, because sulfonate belongs to strong acid and strong alkali salt, the hydrophilic agent has stronger hydrophilicity, the using amount is less when the polyurethane dispersoid is synthesized, and the dispersoid has a more stable double electric layer structure; because the hydrophilic group consumption is small, the influence on the performance of polyurethane is small, so that the performance of the original solvent-based product can be basically maintained by the acid and alkali resistance, electrolyte resistance, mechanical stability, intermiscibility with an auxiliary agent, adhesive film performance and the like of the polyurethane dispersion. However, the prior art has not been studied on sulfonate-based hydrophilic agents, mainly because the alkyl sulfonate has only an external emulsification function, the monohydroxy sulfonate cannot extend the chain of isocyanate, and the good modification effect is the micromolecule dihydroxyl amino sulfonate and the dihydroxyl sulfonate, but the two are expensive, so that the cost of changing oil into water is greatly increased, the fat solubility is poor, and more high-boiling polar solvents need to be added, so that the residual amount of the organic solvent of the product is high, and the popularization is difficult. The prior art CN107082860A discloses a micromolecule diol with molecular weight of 350-1000-containing sulfonic acid group, which reacts with diisocyanate to prepare an aqueous polyurethane curing agent, and introduces a preparation method for preparing the micromolecule diol containing the sulfonic acid group by using dicarboxyl sulfonate and dihydroxy sulfonate, but the conversion conditions are harsh in practical application, and the technology is difficult to master by common enterprises. Because the dicarboxyl sulfonate is convenient in raw material source, low in price, nontoxic and tasteless, if the dicarboxyl sulfonate can be used as a popularization raw material for changing polyurethane oil into water, the water-based process of polyurethane is certainly accelerated.

Accordingly, the present inventors have developed a hydrophilic diisocyanate containing a sulfonate group.

Disclosure of Invention

In order to make up the defects of the prior art, the invention aims to provide the hydrophilic diisocyanate containing the sulfonate group and the preparation method and application thereof.

The application refers to the application of the sulfonate group-containing hydrophilic diisocyanate in the aspects of preparing aqueous polyurethane emulsion, aqueous polyurethane curing agent, aqueous polyurethane binder, aqueous polyurethane finishing agent, aqueous polyurethane elastomer and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

a hydrophilic diisocyanate comprising at least one structural unit having the formula:

in the formula: SO (SO)₃M is sulfonate group, M is K ion or Na ion or ammonium ion, and n is 1-6.

A preparation method of hydrophilic diisocyanate comprises the following steps:

adding diisocyanate and cosolvent into a reaction kettle, starting a stirrer, heating to 30-80 ℃, adding the hydrophilic chain extender in several times, reacting at 50-60 ℃ for 0.5-3 hours after adding the hydrophilic chain extender each time until the hydrophilic chain extender is added in the last time, reacting at 50-60 ℃ for 0.5-3 hours, heating to 60-80 ℃ again for 6-20 hours, cooling and discharging to obtain the hydrophilic diisocyanate.

Preferably, the hydrophilic chain extender is divided into 3-10 parts and added for several times, and after each part of the hydrophilic chain extender is added, the reaction is carried out at 50-60 ℃ until the liquid in the kettle is transparent.

Preferably, the fraction is 3 to 10 times.

Preferably, the molar ratio of the diisocyanate to the hydrophilic chain extender is (2-6): 1.

more preferably, the molar ratio of the diisocyanate to the hydrophilic chain extender is (3-4): 1.

according to the molar ratio of the reaction materials, the following components are obtained: the hydrophilic diisocyanate contains a certain proportion of diisocyanate monomers besides the sulfonate group-containing diisocyanate in the main chain structure, and the prepared prepolymer is soluble in water or emulsifiable with water or dispersible with water as long as a certain proportion of hydrophilic groups exist during the preparation of the waterborne polyurethane, so that a certain proportion of hydrophilic groups are designed in the hydrophilic diisocyanate.

Preferably, the hydrophilic chain extender is a small molecule diol comprising at least one sulfonate group or an amine sulfonate group.

Preferably, the sulfonate group-containing small molecule diol is at least one of 1, 2-dihydroxy-3-propane sodium sulfonate, 1, 4-dihydroxy butane-2-sodium sulfonate or small molecule sulfonate diol.

Preferably, the small molecule diol of the amino sulfonate group is sodium N, N-bis (2-hydroxyethyl) -2-aminoethanesulfonate.

Preferably, the diisocyanate is at least one of MDI, HMDI, TDI, HDI, IPDI or XDI.

Preferably, the micromolecular sulfonate dihydric alcohol is a product obtained by esterification reaction of dicarboxyl sulfonate, micromolecular dihydric alcohol and micromolecular dibasic acid, and the molecular weight is 350-3000.

More preferably, the molecular weight of the small-molecule sulfonate diol is 380-600.

Preferably, the small molecule diol is a diol with a molecular weight of less than 300.

More preferably, the small molecule diol is at least one of 3-methyl-1, 5-pentanediol, neopentyl glycol, ethylene glycol, diethylene glycol, cyclohexanediol, methylpropanediol, TCD tricyclo glycol, 1, 3-propanediol, 1, 4-dimethylolcyclohexane, 1, 4-butanediol, 1, 3-butanediol, 1, 5-pentanediol, diethylpentanediol, 1, 2-propanediol, diethylene glycol, tetrahydrofuran diol, 1, 6-hexanediol, trimethylpentanediol, butylethylpropanediol, 2-bis (4-hydroxyphenyl) propane, dipropylene glycol, tripropylene glycol, or ethylhexanediol.

Preferably, the small molecule diacid is diacid with molecular weight less than 300.

More preferably, the small molecule diacid is at least one of adipic acid, sebacic acid, terephthalic acid, isophthalic acid, phthalic anhydride, dimethyl terephthalate, succinic acid, or glutaric acid.

Preferably, the dicarboxyl sulfonate is at least one of a dicarboxyl sulfonic acid sodium salt, a dicarboxyl sulfonic acid potassium salt, or a dicarboxyl sulfonic acid ammonium salt.

More preferably, the dicarboxy sulfonate is sodium 5-sulfoisophthalate.

Preferably, the cosolvent is added in an amount of 0-40% by weight of the diisocyanate, to obtain a 100% solids content of the hydrophilic diisocyanate.

More preferably, the cosolvent is at least one of acetone, butanone, ethyl acetate, butyl acetate, cyclohexanone, propylene glycol monomethyl ether acetate, N-methylpyrrolidone, tetrahydrofuran, dioxane, or dimethylformamide.

A polyurethane emulsion is prepared by reacting the hydrophilic diisocyanate with dihydroxy compounds to obtain aqueous polyurethane resin with hydroxyl at the end, and then adding water to emulsify and disperse at high speed to obtain the polyurethane emulsion.

Preferably, the dihydroxy compound is at least one of polyester diol, polyether diol, polycaprolactone diol, hydroxyl-terminated alkyd resin, hydroxyl-terminated silicone resin, polyacrylic resin with hydroxyl groups or small molecular diol.

The hydrophilic diisocyanate reacts with dihydroxy compounds (polyester, polyether, micromolecular dihydric alcohol and the like) to prepare aqueous polyurethane resin with hydroxyl at the end, water is added for high-speed dispersion and emulsification to obtain polyurethane emulsion, products with different molecular weights can be prepared by designing OH/NCO to be more than 1, and the chemical reaction formula A is as follows:

in the formula: SO (SO)₃M is sulfonate group, M is K ion or Na ion or ammonium ion, and n is positive integer of 1,2, 3, etc.

The water-based polyurethane curing agent is prepared by reacting the hydrophilic diisocyanate with a polyhydroxy compound.

Preferably, the polyol is at least one of trimethylolpropane, glycerol, trimethylolethane, 1,2, 6-hexanetriol, or pentaerythritol.

The hydrophilic diisocyanate and the polyhydroxy compound are reacted to prepare the polyisocyanate prepolymer, and the water-based polyurethane curing agent can be prepared by designing NCO/OH ≧ 2, and the chemical reaction formula B is as follows:

in the formula: SO (SO)₃M is a sulfonate group, M is a K ion or a Na ion or an ammonium ion.

As can be seen from the above chemical reaction formulas A and B: the hydrophilic diisocyanate facilitates the preparation of the waterborne polyurethane, and the hydrophilic diisocyanate can directly replace part of diisocyanate to react with a hydrogen-containing compound to enable the polyurethane structure of the product to carry hydrophilic sulfonate groups, so that the polyurethane prepolymer becomes hydrophilic and can be dissolved in water or emulsified or dispersed, and various waterborne polyurethane products can be prepared.

The closed water-base polyisocyanate curing agent is prepared by the reaction of the water-base polyurethane curing agent and a closing agent.

Preferably, the aqueous polyurethane curing agent is a polyisocyanate prepolymer prepared by reacting the hydrophilic diisocyanate of the present invention with a polyol.

Preferably, the blocking agent is a hydrogen-containing compound.

More preferably, the blocking agent is at least one of methanol, ethanol, isopropanol, tert-butanol, propylene glycol monomethyl ether, methyl ethyl ketoxime, acetoxime, methyl isobutyl oxime, imidazole, 2-methylpyrazole, 3, 5-dimethylpyrazole, 3-methyl-5-ethylpyrazole, 3-ethyl-5-propylpyrazole, acetylacetone, ethyl acetoacetate, -caprolactam, phenol or catechol.

An application of hydrophilic diisocyanate in preparing water-based polyurethane coating, water-based polyurethane adhesive, water-based polyurethane binder, water-based leather finishing agent, water-based fabric finishing agent or water-based ink binder.

Preferably, the aqueous polyurethane emulsion with hydroxyl at the end and the aqueous polyurethane curing agent with polyisocyanate at the end can be combined into a two-component aqueous polyurethane coating and an aqueous polyurethane adhesive, and the aqueous polyurethane curing agent with polyisocyanate at the end and the aqueous resin with hydroxyl can be combined into an aqueous polyurethane binder, an aqueous leather finishing agent, an aqueous fabric finishing agent or an aqueous ink binder and the like.

Advantageous effects

1. The sulfonate group in the structure of the hydrophilic diisocyanate is strong acid strong alkali salt, has good hydrophilicity, and the isocyanate groups at two ends retain the performance of the original diisocyanate, so the hydrophilic diisocyanate has the chemical reaction characteristic of the diisocyanate; the preparation of the waterborne polyurethane by using the hydrophilic diisocyanate changes the prior process method and greatly simplifies the operation. The method for preparing the hydrophilic diisocyanate is simple, can be used for batch production, can directly use the hydrophilic diisocyanate to prepare the waterborne polyurethane, can reduce the cost, and is favorable for popularization and application of changing polyurethane oil into water.

2. The hydrophilic diisocyanate product of the present invention has stable performance. Because the property of the sulfonate is stable, the hydrophilic diisocyanate generated after the diisocyanate is modified by the sulfonate group still has a stable structure, and the storage experiment proves that: different types of products have more than half a year of storage period and can be sold as hydrophilic diisocyanate raw materials.

3. The variety is many. According to different compositions and proportions of the prepared raw materials, a series of hydrophilic diisocyanates with different types can be prepared, and each product has specific NCO%, viscosity and storage period, so that a user can select a variety with a proper type according to the performance of a specific waterborne polyurethane product.

4. The method for changing oil into water is simple. When the hydrophilic diisocyanate of the invention is used for replacing partial diisocyanate to prepare the waterborne polyurethane, the polyurethane product which is soluble, emulsifiable or water dispersible in water can be produced by designing the molar ratio of reactants according to the product performance and using the process method for producing the solvent type polyurethane which is familiar to the technical personnel in the field; furthermore, the hydrophilic diisocyanate can be directly added into the solvent type polyisocyanate prepolymer (polyurethane curing agent) to make the polyisocyanate prepolymer hydrophilic, and then the hydrophilic diisocyanate is mixed with polyurethane resin emulsion, acrylic resin emulsion, alkyd resin emulsion and the like to be used as a cross-linking agent of the resin emulsions, so that the aim of quickly changing the water of the polyurethane oil is fulfilled.

5. The production stability of changing oil into water is good. The invention can prepare aliphatic, alicyclic or aromatic hydrophilic diisocyanate, so that the performances of different types of diisocyanate can be effectively utilized. In the prior art, the polyurethane emulsion is mainly prepared from aliphatic or alicyclic diisocyanate, and the preparation technology is difficult because the activity of the aromatic diisocyanate is high. For example: when the dimethylolcarboxylic acid is used for preparing the aqueous polyurethane resin, HDI or IPDI is generally adopted, because the dimethylolcarboxylic acid is a trifunctional compound, gel is easily generated in the production process, the quality is unstable, and particularly, the explosion polymerization is generated in industrial mass production by carelessness. When the invention is used for preparing the waterborne polyurethane resin, the hydrophilic diisocyanate has two functionality degrees and directly reacts with the dihydroxy prepolymer, the production process is easy to control, the operation is simple, and the product quality is stable.

6. The environmental protection is good. The hydrophilic diisocyanate can be prepared into a waterborne polyurethane product with 100% solid content and no VOC emission, and can be further prepared into an organic solvent-free waterborne polyurethane product.

7. The application range is wide. The hydrophilic diisocyanate can be used for preparing aqueous polyurethane emulsion, aqueous polyurethane curing agent and other aqueous polyurethane, can be further prepared into two-component aqueous polyurethane adhesive, aqueous polyurethane coating and other aqueous polyurethane products, and can be used for conveniently modifying solvent type polyurethane into aqueous polyurethane.

Detailed Description

A hydrophilic diisocyanate comprising at least one structural unit having the formula:

in the formula: SO (SO)₃M is sulfonate group, M is K ion or Na ion or ammonium ion, and n is 1-6.

A preparation method of hydrophilic diisocyanate comprises the following steps:

adding diisocyanate and cosolvent into a reaction kettle, starting a stirrer, heating to 30-80 ℃, adding the hydrophilic chain extender in several times, reacting at 50-60 ℃ for 0.5-3 hours after adding the hydrophilic chain extender each time until the hydrophilic chain extender is added in the last time, reacting at 50-60 ℃ for 0.5-3 hours, heating to 60-80 ℃ again for 6-20 hours, cooling and discharging to obtain the hydrophilic diisocyanate.

The hydrophilic chain extender is divided into 3-10 parts and added for several times, and after each part of the hydrophilic chain extender is added, the reaction is carried out at 50-60 ℃ until the liquid in the kettle is transparent.

The molar ratio of the reaction materials is diisocyanate: the hydrophilic chain extender is (3-4): 1.

the hydrophilic chain extender is a small molecule diol containing at least one sulfonate group-containing small molecule diol or an amine sulfonate group-containing small molecule diol.

The micromolecular dihydric alcohol containing sulfonate group is at least one of 1, 2-dihydroxy-3-propanesulfonic acid sodium salt, 1, 4-dihydroxy butane-2-sulfonic acid sodium salt or micromolecular sulfonate dihydric alcohol.

The micromolecule dihydric alcohol containing the amidosulfate group is N, N-di (2-hydroxyethyl) -2-aminoethanesulfonic acid sodium salt.

The diisocyanate is at least one of MDI, HMDI, TDI, HDI, IPDI and XDI.

The micromolecular sulfonate dihydric alcohol is a product obtained by esterification reaction of dicarboxyl sulfonate, micromolecular dihydric alcohol and micromolecular dibasic acid, and the molecular weight of the micromolecular sulfonate dihydric alcohol is 380-600.

The dicarboxyl sulfonate is 5-sodium m-phthalate sulfonate.

The micromolecular dihydric alcohol is dihydric alcohol with the molecular weight less than 300; further, the small molecule diol is at least one of 3-methyl-1, 5-pentanediol, neopentyl glycol, ethylene glycol, diethylene glycol, cyclohexanediol, methylpropanediol, TCD tricyclo glycol, 1, 3-propanediol, 1, 4-dimethylolcyclohexane, 1, 4-butanediol, 1, 3-butanediol, 1, 5-pentanediol, diethylpentanediol, 1, 2-propanediol, diethylene glycol, tetrahydrofuran diol, 1, 6-hexanediol, trimethylpentanediol, butylethylpropanediol, 2-bis (4-hydroxyphenyl) propane, dipropylene glycol, tripropylene glycol, or ethylhexanediol.

The micromolecular dibasic acid is dibasic acid with the molecular weight less than 300; further, the small molecule dibasic acid is at least one of adipic acid, sebacic acid, terephthalic acid, isophthalic acid, phthalic anhydride, dimethyl terephthalate, succinic acid, and glutaric acid.

The addition amount of the cosolvent is 0-40% of the weight of the diisocyanate, and the cosolvent is at least one of acetone, butanone, ethyl acetate, butyl acetate, cyclohexanone, propylene glycol monomethyl ether acetate, N-methylpyrrolidone, tetrahydrofuran, dioxane or dimethylformamide.

The average molecular weight and NCO% of the hydrophilic diisocyanate can be calculated or tested.

A polyurethane emulsion is prepared through reaction between hydrophilic diisocyanate and dihydroxy compound to obtain the aqueous polyurethane resin with hydroxy end, and high-speed emulsifying.

The preparation method of the polyurethane emulsion comprises the following steps: adding the dihydroxy compound and the cosolvent which are dehydrated in vacuum into a reaction kettle, stirring uniformly, heating to 60 ℃, adding hydrophilic diisocyanate and a catalyst, heating to 70-100 ℃, performing chain extension reaction for 6-15 hours to obtain a polyurethane prepolymer with a hydroxyl main chain structure at the end and containing sulfonate, adding water, emulsifying and dispersing at high speed, and removing the cosolvent to obtain the hydroxyl-terminated waterborne polyurethane emulsion.

The dihydroxy compound is at least one of polyester diol, polyether diol, polycaprolactone diol, hydroxyl-terminated alkyd resin, hydroxyl-terminated organic silicon resin, polyacrylic resin with hydroxyl or micromolecular diol.

The invention relates to a waterborne polyurethane curing agent, which is a waterborne polyurethane prepolymer (waterborne polyurethane curing agent) with a terminal band containing polyisocyanate prepared by reacting hydrophilic diisocyanate with a polyhydroxy compound, and the preparation method comprises the following steps:

adding hydrophilic diisocyanate and cosolvent into a reaction kettle, stirring uniformly, adding the polyol dehydrated in vacuum, stirring for 0.5-2 hours at room temperature, heating to 50-100 ℃ and reacting for 2-10 hours to obtain polyisocyanate prepolymer with a main chain structure containing sulfonate groups, and removing the cosolvent to obtain the waterborne polyurethane curing agent.

The polyhydroxy compound is at least one of trimethylolpropane, glycerol, trimethylolethane, 1,2, 6-hexanetriol, pentaerythritol, polyester polyol or polyether polyol.

A blocked water-based polyisocyanate curing agent is prepared by reacting a polyisocyanate prepolymer with a sulfonate group in a main chain structure with a blocking agent.

The sealing agent is at least one of methanol, ethanol, isopropanol, tert-butanol, propylene glycol monomethyl ether, methyl ethyl ketoxime, acetone oxime, methyl isobutyl oxime, imidazole, 2-methylpyrazole, 3, 5-dimethylpyrazole, 3-methyl-5-ethylpyrazole, 3-ethyl-5-propylpyrazole, acetylacetone, ethyl acetoacetate, -caprolactam, phenol or catechol.

An application of hydrophilic diisocyanate in preparing water-based polyurethane coating, water-based polyurethane adhesive, water-based polyurethane binder, water-based leather finishing agent, water-based fabric finishing agent or water-based ink binder.

The waterborne polyurethane emulsion with hydroxyl at the end and the waterborne polyurethane curing agent with the polyisocyanate at the end can be combined into a two-component waterborne polyurethane coating and a waterborne polyurethane adhesive, and the waterborne polyurethane curing agent with the polyisocyanate at the end and the waterborne resin with the hydroxyl can be combined into a waterborne polyurethane binder, a waterborne leather finishing agent, a waterborne fabric finishing agent or a waterborne ink binder.

The present invention will be described in further detail with reference to specific examples.

In the following examples:

1. the viscosity was measured according to the national Standard GB/T2794-1995 determination of the viscosity of the adhesive.

2. The NCO content was measured according to the Standard of chemical industry "determination of isocyanate group content in HG/T2409-92 polyurethane prepolymer".

3. Molecular weight was measured by GPC gel chromatography.

4. The hydroxyl value was measured according to the Standard of chemical industry "determination of resin value of HG/T2709-95".