CN114230764B - Water-based closed polyisocyanate curing agent and preparation method and application thereof - Google Patents
Water-based closed polyisocyanate curing agent and preparation method and application thereof Download PDFInfo
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- CN114230764B CN114230764B CN202111576048.3A CN202111576048A CN114230764B CN 114230764 B CN114230764 B CN 114230764B CN 202111576048 A CN202111576048 A CN 202111576048A CN 114230764 B CN114230764 B CN 114230764B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/80—Masked polyisocyanates
- C08G18/8061—Masked polyisocyanates masked with compounds having only one group containing active hydrogen
- C08G18/8083—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with compounds containing at least one heteroatom other than oxygen or nitrogen
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/80—Masked polyisocyanates
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
- C09D175/04—Polyurethanes
Abstract
The invention belongs to the technical field of paint curing agents, and discloses a water-based closed polyisocyanate curing agent, and a preparation method and application thereof. The preparation method comprises the following steps: mixing sulfonate, diisocyanate trimer and catalyst, performing a first reaction, adding bisulfite after the reaction is finished, and performing a second reaction to obtain the water-based closed polyisocyanate curing agent. The aqueous closed polyisocyanate curing agent provided by the invention uses the bisulphite as a sealing agent, has low deblocking temperature, has excellent water dispersibility and storage stability, and can be applied to various baking coatings. The aqueous polyurethane coating prepared by the aqueous closed polyisocyanate curing agent provided by the invention has the advantages of strong stability, small change of storage viscosity at high temperature, high glossiness of a formed paint film and high transparency.
Description
Technical Field
The invention belongs to the technical field of paint curing agents, and particularly relates to a water-based closed polyisocyanate curing agent, and a preparation method and application thereof.
Background
With the importance of people on environmental protection, the environmental protection requirement is continuously improved, and the water-based paint is undoubtedly one of the important development directions of the current paint technology. Among them, the film obtained by using the aqueous polyurethane-based coating material having an isocyanate-based compound crosslinking effect has very excellent abrasion resistance, drug resistance and stain resistance, and is widely used.
The aqueous isocyanate curing agent has excellent performance, and due to the high reactivity of isocyanate groups, the aqueous isocyanate curing agent can be crosslinked and cured with polymers with active hydrogen atoms such as alcohols, amines and the like at room temperature, so that the aqueous isocyanate curing agent can be basically only used in two-component coatings, and the application of the aqueous isocyanate curing agent is limited. In addition, the aqueous isocyanate curing agent is extremely sensitive to water in the environment because a large amount of hydrophilic groups are introduced, so that the storage difficulty of the aqueous isocyanate curing agent is greatly increased. In order to solve the technical problem, the water-based blocked polyisocyanate curing agent is developed, and the active isocyanate groups are protected by using the small molecule blocking agent, so that the crosslinking agent can stably coexist with other components in the coating at room temperature, and the storage difficulty is greatly reduced.
At present, the blocked polyisocyanate is prepared by reacting 3, 5-dimethylpyrazole or methyl ethyl ketoxime serving as a blocking agent with an HDI trimer (hexamethylene diisocyanate trimer) or an IPDI trimer. Then mixing the modified acrylic resin or amino resin according to a certain proportion to prepare the automobile coating, wherein the product has the advantages of good chemical resistance, yellowing resistance and the like, but the deblocking temperature (baking temperature) is higher, and is generally 100-150 ℃; and most contain a large amount of low boiling point solvent.
Therefore, it is desirable to provide an aqueous blocked polyisocyanate curing agent that reduces the amount of low boiling point solvents, reduces the deblocking temperature, and provides polyurethane coatings with good storage stability.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the prior art described above. Therefore, the invention provides an aqueous closed polyisocyanate curing agent, and a preparation method and application thereof. The aqueous closed polyisocyanate curing agent provided by the invention can reduce the dosage of low-boiling point solvent, lower the deblocking temperature, and the prepared polyurethane coating has good storage stability.
The invention provides a preparation method of an aqueous closed polyisocyanate curing agent.
Specifically, the preparation method of the water-based closed polyisocyanate curing agent comprises the following steps:
mixing sulfonate, diisocyanate trimer and catalyst, performing a first reaction, adding bisulfite after the reaction is finished, and performing a second reaction to obtain the water-based closed polyisocyanate curing agent.
Preferably, the sulfonate is sulfamate; further preferably, the sulfamate is at least one of sodium 2-tert-butyl-4- (cyclohexylamino) -1-butanesulfonate, sodium 2-tert-butyl-3- (cyclohexylamino) -1-propanesulfonate or sodium 2-isopentyl-3- (cyclohexylamino) -1-propanesulfonate; the polyurethane sulfonate and diisocyanate trimer are used for synthesizing the polyisocyanate, so that the hydrophilic property of the polyisocyanate is provided, and the water-based polyisocyanate curing agent is ensured to have excellent dispersibility without solvent dilution.
Preferably, the diisocyanate trimer is selected from at least one of isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, toluene diisocyanate trimer or diphenylmethane diisocyanate trimer; further preferably, the diisocyanate trimer is selected from isophorone diisocyanate trimer and/or hexamethylene diisocyanate trimer. The hexamethylene diisocyanate trimer and isophorone diisocyanate trimer have mild reaction and are easy to control in the hydrophilization process.
Preferably, the diisocyanate trimer has an-NCO content of 18% wt to 28% wt; further preferably, the diisocyanate trimer has an-NCO content of 21% by weight to 24% by weight.
Preferably, the temperature of the first reaction is 70-110 ℃, and the time of the first reaction is 1-15h; further preferably, the temperature of the first reaction is 80-100 ℃, and the time of the first reaction is 3-10h.
Preferably, the bisulphite is selected from at least one of sodium bisulphite, potassium bisulphite, magnesium bisulphite or calcium bisulphite.
Preferably, in the preparation method, the sulfonate is 1 to 8 parts by weight, the diisocyanate trimer is 80 to 120 parts by weight, and the bisulfite is 40 to 70 parts by weight.
Further preferably, in the production method, the sulfonate is 1.5 to 5 parts by weight, the diisocyanate trimer is 95 to 100 parts by weight, and the bisulfite is 50 to 60 parts by weight.
Preferably, the catalyst is azadimethylbenzylamine. The catalyst is 0.15-0.5 parts by weight.
Preferably, the temperature of the second reaction is 40-70 ℃; the time of the second reaction is 2-10h; further preferably, the temperature of the second reaction is 50-60 ℃; the time of the second reaction is 3-8h.
Preferably, the second reaction is terminated when the mass content of-NCO in the reaction system is less than 0.05%. The end point of the second reaction is based on the fact that the mass content of isocyanate is reduced to below 0.05%, and the content of isocyanate is measured by adopting a toluene-di-n-butylamine titration method. By controlling the content of-NCO in the reaction system, excessive residual-NCO and water react to chain extend when water is added for dilution in the subsequent processes of preparing the paint and the like are avoided, so that the viscosity of the system is too high, and the dispersion and the use are not facilitated.
Preferably, the first reaction and the second reaction are carried out under a protective gas. Such as nitrogen.
Preferably, the preparation method of the water-based blocked polyisocyanate curing agent comprises the following steps:
mixing sulfonate, diisocyanate trimer and catalyst, reacting at 70-110 deg.c for 1-15 hr, adding bisulphite after the reaction is completed, and finishing the reaction at 40-70 deg.c until the-NCO content is less than 0.05% to obtain the water-base closed polyisocyanate curing agent.
Further preferably, the preparation method of the aqueous blocked polyisocyanate curing agent comprises the following steps:
mixing sulfonate, diisocyanate trimer and catalyst, reacting at 80-100 deg.c for 3-10 hr, adding bisulphite after the reaction, and finishing the reaction at 50-60 deg.c until the-NCO content is less than 0.05 wt% to obtain the water blocked polyisocyanate curing agent.
In a second aspect, the present invention provides an aqueous blocked polyisocyanate curing agent.
In particular to an aqueous closed polyisocyanate curing agent which is prepared by the preparation method, wherein the solid content of the polyisocyanate curing agent is 99-100%, and the closing rate is more than 99.9%.
In a third aspect, the invention provides the use of an aqueous blocked polyisocyanate curing agent.
In particular to the application of the aqueous closed type polyisocyanate curing agent in polyurethane paint. Preferably, the polyurethane coating is an aqueous polyurethane coating.
An aqueous polyurethane coating comprises an A component and a B component, wherein the A component comprises an aqueous polyurethane dispersion, and the B component comprises the aqueous blocked polyisocyanate curing agent.
Further preferably, the a-component further comprises a wetting agent, a thickener, a leveling agent and a solvent.
Preferably, the mass ratio of the A component to the B component is (3-8): 1.
Preferably, the preparation method of the water-based polyurethane coating comprises the following steps: and mixing the component A and the component B to obtain the product. In fact, the A component and the B component in the aqueous polyurethane coating provided by the invention can be stored after being mixed, and have good storage stability; the A component and the B component can also be stored separately and mixed for use. The specific manner may be selected according to different circumstances and requirements.
The invention uses bisulphite to seal the water-based polyisocyanate obtained by the reaction of sulfonate and diisocyanate trimer, and prepares the water-based sealed polyisocyanate curing agent. Specifically, the isocyanate groups of the aqueous polyisocyanate are blocked in the preparation using the catalyst present in the reaction system as a phase transfer catalyst for the bisulfite (blocking agent). The reaction condition is mild, and no additional catalyst is needed, so that the system is more stable in later storage; the prepared aqueous closed polyisocyanate curing agent has low deblocking temperature (about 75 ℃) and can be applied to various baking coatings; the aqueous polyurethane coating prepared by the method has strong stability, small change of storage viscosity at high temperature and high glossiness of a formed paint film.
Compared with the prior art, the invention has the following beneficial effects:
(1) The aqueous blocked polyisocyanate curing agent provided by the invention uses the bisulphite as a blocking agent, has excellent water dispersibility and storage stability, has low deblocking temperature (not more than 80 ℃), and can be applied to various baking coatings.
(2) The aqueous polyurethane coating prepared by the aqueous closed polyisocyanate curing agent provided by the invention has the advantages of strong stability, small change of storage viscosity at high temperature, high glossiness of a formed paint film and high transparency.
(3) The aqueous closed polyisocyanate curing agent disclosed by the invention can reduce the dosage of a low-boiling point solvent, does not need to use any high-boiling point solvent or ketone solvent for viscosity reduction, and effectively controls VOC (volatile organic compounds) in the curing agent and the coating; and the preparation process is simple and environment-friendly.
Detailed Description
In order to make the technical solutions of the present invention more apparent to those skilled in the art, the following examples will be presented. It should be noted that the following examples do not limit the scope of the invention.
In the following examples, comparative examples, application examples or comparative application examples, the aqueous polyurethane dispersion Bayhydrol@2470 was purchased from Kogyo Polymer (China) Co., ltd., wetting agent
Twin 4100、/>
Tain 810 was purchased from Yingchangdi corporation and thickener COAPUR XS71 was purchased from Gaotai corporation, france. The remaining materials, reagents or apparatus, unless otherwise specified, are available from conventional commercial sources or may be obtained by methods known in the art.
Example 1
A preparation method of an aqueous closed polyisocyanate curing agent comprises the following steps:
raw materials were prepared according to the formulations shown in table 1. 97.1 parts by mass of hexamethylene diisocyanate trimer was put into a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, heated to 60 ℃, 2.8 parts by mass of sodium 2-tert-butyl-4- (cyclohexylamino) -1-butanesulfonate and 0.2 part by mass of azodimethylbenzylamine were added under stirring, reacted at 80 ℃ for 6 hours, and then sampled and detected for isocyanate content (the toluene-di-n-butylamine titration method in HGT 2409-1992 was adopted for isocyanate content measurement), sodium bisulfate was added until the isocyanate content was close to a theoretical value (the mass content of which is not more than 0.5% from the theoretical value), reacted at 55 ℃ for 5 hours, and then sampled and detected for isocyanate content until the isocyanate content of which is less than 0.05% was completed, thereby obtaining the aqueous closed polyisocyanate curing agent. The solid content of the prepared aqueous blocked polyisocyanate curing agent is 99.7%, and the blocking rate is 99.97%. (by measuring the mass content of-NCO, the blocking ratio was calculated, blocking ratio = (mass content of-NCO before blocking-mass content of-NCO after blocking)/mass content of-NCO before blocking.)
TABLE 1
| Raw material type | Parts by mass |
| Hexamethylene diisocyanate trimer | 97.1 |
| 2-tert-butyl-4- (cyclohexylamino) -1-butanesulfonic acid sodium salt | 2.8 |
| Azomethine benzylamine | 0.2 |
| Sodium bisulfite | 60 |
Example 2
A preparation method of an aqueous closed polyisocyanate curing agent comprises the following steps:
raw materials were prepared according to the formulations shown in table 2. 96.9 parts by mass of hexamethylene diisocyanate trimer was put into a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, heated to 60 ℃, 3.0 parts by mass of sodium 2-tert-butyl-4- (cyclohexylamino) -1-butanesulfonate and 0.35 parts by mass of azodimethylbenzylamine were added under stirring, reacted at 90 ℃ for 4.5 hours, then sampled and detected for isocyanate content (toluene-di-n-butylamine titration method in HGT 2409-1992 was adopted for isocyanate content measurement), sodium hydrogensulfite was added until the isocyanate content was close to the theoretical value (the mass content of isocyanate content was not more than 0.5% from the theoretical value, then reacted at 55 ℃ for 5 hours, and the reaction was terminated when the mass content of isocyanate was less than 0.05% to obtain the aqueous closed polyisocyanate curing agent. The solid content of the prepared aqueous blocked polyisocyanate curing agent is 99.5%, and the blocking rate is 99.5%.
TABLE 2
| Raw material type | Parts by mass |
| Hexamethylene diisocyanate trimer | 96.9 |
| 2-tert-butyl-4- (cyclohexylamino) -1-butanesulfonic acid sodium salt | 3.0 |
| Azomethine benzylamine | 0.35 |
| Sodium bisulfite | 55 |
Example 3
A preparation method of an aqueous closed polyisocyanate curing agent comprises the following steps:
raw materials were prepared according to the formulations shown in table 3. 97.1 parts by mass of hexamethylene diisocyanate trimer was charged into a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, heated to 60℃and 2.8 parts by mass of sodium 2-t-butyl-4- (cyclohexylamino) -1-butanesulfonate and 0.5 part by mass of azodimethylbenzylamine were added under stirring; after reacting for 5.5 hours at 80 ℃, sampling and detecting the isocyanate content (the determination of the isocyanate content adopts a toluene-di-n-butylamine titration method in HGT 2409-1992), and adding sodium bisulphite when the isocyanate content is close to a theoretical value (the mass content is not more than 0.5% different from the mass content of 0.05% of the theoretical value); and then reacting for 5 hours at 55 ℃, and ending the reaction when the mass content of isocyanate groups is less than 0.05%, thus obtaining the water-based closed polyisocyanate curing agent. The solid content of the prepared aqueous blocked polyisocyanate curing agent is 99.5%, and the blocking rate is 99.96%.
TABLE 3 Table 3
| Raw material type | Parts by mass |
| Hexamethylene diisocyanate trimer | 97.1 |
| 2-tert-butyl-4- (cyclohexylamino) -1-butanesulfonic acid sodium salt | 2.8 |
| Azomethine benzylamine | 0.5 |
| Sodium bisulfite | 58 |
Example 4
A preparation method of an aqueous closed polyisocyanate curing agent comprises the following steps:
raw materials were prepared according to the formulations shown in table 4. 97.1 parts by mass of isophorone diisocyanate trimer was put into a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, heated to 60 ℃, 2.8 parts by mass of 2-tert-butyl-3- (cyclohexylamino) -1-propane sodium sulfonate and 0.2 parts by mass of nitrogen dimethyl benzyl amine were added under stirring, reacted at 80 ℃ for 6 hours, then the reaction was sampled and detected for isocyanate content (toluene-di-n-butylamine titration method in HGT 2409-1992 was adopted for isocyanate content measurement), potassium hydrogen sulfite was added until the isocyanate content was close to the theoretical value (the mass content of the isocyanate content was not more than 0.5% from the theoretical value, reacted at 55 ℃ for 5 hours, and then the reaction was ended after the mass content of the isocyanate was less than 0.05% by sampling, to obtain the aqueous closed polyisocyanate curing agent. The solid content of the prepared aqueous blocked polyisocyanate curing agent is 99.8%, and the blocking rate is 99.97%.
TABLE 4 Table 4
Comparative example 1
Comparative example 1 differs from example 3 in that the same amount of methyl ethyl ketoxime was used instead of sodium bisulfite as the blocking agent, and the remaining materials and preparation method were the same as in example 3.
Specifically, the preparation method of the water-based closed polyisocyanate curing agent comprises the following steps:
97.1 parts by mass of hexamethylene diisocyanate trimer was charged into a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, heated to 60℃and 2.8 parts by mass of sodium 2-t-butyl-4- (cyclohexylamino) -1-butanesulfonate and 0.5 part by mass of azodimethylbenzylamine were added under stirring; after reacting at 80 ℃ for 5.5 hours, sampling and detecting the isocyanate content (the determination of the isocyanate content adopts a toluene-di-n-butylamine titration method in HGT 2409-1992), and adding 58 parts of methyl ethyl ketone oxime when the isocyanate content approaches a theoretical value (the mass content of the toluene-di-n-butylamine titration method is not more than 0.5% different from the mass content of the toluene-di-n-butylamine in 0.05% of the theoretical value); and then reacting for 5 hours at 55 ℃, and ending the reaction when the mass content of isocyanate groups is less than 0.05%, thus obtaining the water-based closed polyisocyanate curing agent. The solid content of the prepared aqueous blocked polyisocyanate curing agent is 99.8%, and the blocking rate is 99.95%.
Comparative example 2
Comparative example 2 differs from example 3 in that sodium 2-t-butyl-4- (cyclohexylamino) -1-butanesulfonate was not added, and the remaining raw materials and preparation method were the same as in example 3.
A method for preparing a blocked polyisocyanate curing agent, comprising the steps of:
raw materials were prepared according to the formulations shown in table 3. 97.1 parts by mass of hexamethylene diisocyanate trimer was put into a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, heated to 60℃and charged with 0.5 parts by mass of azoteme and 58 parts by mass of sodium hydrogensulfite under stirring; and (3) reacting for 5 hours at 55 ℃, and ending the reaction when the mass content of isocyanate groups is less than 0.05%, thus obtaining the closed polyisocyanate curing agent. The solid content of the prepared blocked polyisocyanate curing agent is 99.9%, and the blocking rate is 99.96%.
Comparative example 3
Comparative example 3 differs from example 3 in that the blocking agent sodium bisulphite was not added, and the remaining raw materials and preparation method were the same as example 3.
A preparation method of an aqueous polyisocyanate curing agent comprises the following steps:
97.1 parts by mass of hexamethylene diisocyanate trimer was charged into a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet, heated to 60℃and 2.8 parts by mass of sodium 2-t-butyl-4- (cyclohexylamino) -1-butanesulfonate and 0.5 part by mass of azodimethylbenzylamine were added under stirring; after reacting for 5.5 hours at 80 ℃, sampling and detecting the isocyanate content (the determination of the isocyanate content adopts a toluene-di-n-butylamine titration method in HGT 2409-1992), and ending the reaction when the mass content of isocyanate is less than 0.05%, thus obtaining the water-based polyisocyanate curing agent. The solid content of the prepared aqueous polyisocyanate curing agent is 99.9%, and the curing agent is unblocked and has no blocking rate data.
Application examples 1 to 4
Waterborne polyurethane coatings are respectively prepared by adopting the waterborne closed polyisocyanate curing agents prepared in the examples 1-4.
Specifically, the preparation method of the water-based polyurethane coating comprises the following steps:
(1) Taking 80% aqueous polyurethane dispersion Bayhydrol@2470 and 0.25% wetting agent by mass percent
Twain 4100, 0.15% wetting agent->
Twain 810, 2.5% dipropylene glycol butyl ether, 2.5% dipropylene glycol monomethyl ether, 0.25% thickener COAPUR XS71, 0.35% water-based leveling agent BYK-333 and 14% water, and mixing to prepare a component A;
(2) The mass ratio of the components according to A, B is 5:1, respectively weighing the component B (the water-based closed polyisocyanate curing agents prepared in examples 1-4) and adding the component A, and uniformly mixing to prepare the water-based polyurethane coating.
Comparative application examples 1 to 3
The polyisocyanate curing agents prepared in comparative examples 1 to 3 were used to prepare waterborne polyurethane coatings.
Specifically, the preparation method of the water-based polyurethane coating comprises the following steps:
(1) Taking 80% aqueous polyurethane dispersion Bayhydrol@2470 and 0.25% wetting agent by mass percent
Twain 4100, 0.15% wetting agent->
Twain 810, 2.5% dipropylene glycol butyl ether, 2.5% dipropylene glycol monomethyl ether, 0.25% thickener COAPUR XS71. Mixing 0.35% of water-based leveling agent BYK-333 and 14% of water to prepare a component A;
(2) The mass ratio of the components according to A, B is 5:1, respectively weighing the component B (the polyisocyanate curing agents prepared in comparative examples 1-3) and adding the component A, and uniformly mixing to prepare the water-based polyurethane coating.
Product effect test
The aqueous polyurethane coatings prepared in application examples 1-4 and comparative application examples 1-3 are respectively used for preparing a paint film by using a 150 mu m wet film preparation device, baking is carried out according to the deblocking temperature of the paint film, and the paint film is obtained after drying and crosslinking. And (3) performing performance tests on the water-based closed polyisocyanate curing agent, the water-based polyurethane coating and the prepared paint film. The tests on the aqueous blocked polyisocyanate curing agent comprise the test of water solubility and deblocking temperature, the test on the aqueous polyurethane coating comprises the test of stability (viscosity, paint film gloss) in high temperature storage (6 months storage at 50 ℃), and the test on the paint film comprises the paint film gloss test. The test method of the basic questions is as follows:
(1) The deblocking temperature measurement method comprises the following steps: after the water-based closed isocyanate curing agent is dissolved by acetone, a plurality of drops of phenol are added, and the temperature is raised and heated. The temperature at which haze occurs is the initial deblocking temperature of the sample.
(2) Measurement of viscosity: GB/T1723-1993.
(3) Measurement of paint film gloss: GBT 9754-2007.
The test results are shown in Table 5.
Table 5 technical index of aqueous blocked polyisocyanate curing agent and test results for making aqueous polyurethane coating
As shown in Table 5, the aqueous blocked polyisocyanate curing agent provided by the embodiment of the invention has excellent water solubility, and very small particles (the 90% particle size of the system is lower than 0.9 μm) are formed after the agent is dispersed in water, so that the transparency and glossiness of the aqueous polyurethane coating are improved; the deblocking temperature of the aqueous blocked polyisocyanate curing agent is as low as 70 ℃; the aqueous polyurethane coating prepared by the method has strong stability and small viscosity change after being stored for 6 months at 50 ℃; the glossiness of the paint film prepared by the method is high and reaches 90 degrees or more, the glossiness of the paint film prepared by the water-based polyurethane paint is still high after the water-based polyurethane paint is stored for 6 months at 50 ℃, the water-based polyurethane paint is basically unchanged, and the water-based polyurethane paint has good storage stability. Whereas the deblocking temperature in comparative application example 1 was as high as 140 ℃; the curing agent in comparative application example 2, although also having a lower deblocking temperature, is poor in water solubility and the gloss of the paint film is markedly inferior to that of the application example; comparative application example 3 has poor storage stability. Meanwhile, through tests, the haze of the paint film prepared by the application example of the invention is lower than 20%, the light transmittance is higher than 85%, and the paint film has higher transparency.
Claims (10)
1. A method for preparing a polyisocyanate curing agent, comprising the steps of: mixing sulfonate, diisocyanate trimer and a catalyst, performing a first reaction, adding bisulfite after the reaction is finished, and performing a second reaction to obtain the water-based closed polyisocyanate curing agent;
the catalyst is azotemyl benzyl amine.
2. The method of claim 1, wherein the sulfonate salt is sulfamate salt.
3. The method according to claim 1, wherein the diisocyanate trimer is at least one selected from isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, toluene diisocyanate trimer and diphenylmethane diisocyanate trimer.
4. The method according to claim 1, wherein the bisulfite is at least one selected from the group consisting of sodium bisulfite, potassium bisulfite, magnesium bisulfite, and calcium bisulfite.
5. The method according to any one of claims 1 to 4, wherein in the method, the sulfonate is 1 to 8 parts by weight, the diisocyanate trimer is 80 to 120 parts by weight, and the bisulfite is 40 to 70 parts by weight.
6. The process of claim 1, wherein the temperature of the second reaction is 40-70 ℃.
7. The process according to claim 6, wherein the second reaction is terminated when the mass content of-NCO in the reaction system is less than 0.05%.
8. A polyisocyanate curing agent characterized in that it is produced by the production method according to any one of claims 1 to 7, the solid content of said polyisocyanate curing agent being 99 to 100% and the blocking ratio being greater than 99.9%.
9. Use of the polyisocyanate curing agent of claim 8 in polyurethane coatings.
10. An aqueous polyurethane coating comprising an a-component comprising an aqueous polyurethane dispersion and a B-component comprising the polyisocyanate curing agent of claim 8.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111576048.3A CN114230764B (en) | 2021-12-20 | 2021-12-20 | Water-based closed polyisocyanate curing agent and preparation method and application thereof |
| PCT/CN2022/128657 WO2023116204A1 (en) | 2021-12-20 | 2022-10-31 | Water-based blocked polyisocyanate curing agent, and preparation method therefor and application thereof |
| ZA2023/08970A ZA202308970B (en) | 2021-12-20 | 2023-09-21 | Water-based sealed polyisocyanate curing agent and preparation method and application thereof |
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| CN114230764B (en) * | 2021-12-20 | 2023-06-13 | 嘉宝莉化工集团股份有限公司 | Water-based closed polyisocyanate curing agent and preparation method and application thereof |
| CN115613369B (en) * | 2022-10-20 | 2024-04-16 | 莆田达凯新材料有限公司 | Heat-resistant polyurethane vamp coating, heat-resistant polyurethane coating vamp and preparation method thereof |
| CN117304429B (en) * | 2023-11-29 | 2024-02-02 | 大庆市唯品科技开发有限公司 | Composite high-temperature-resistant and salt-resistant water shutoff agent and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101675132A (en) * | 2007-05-04 | 2010-03-17 | 巴斯福涂料股份公司 | Water-based two-layer coating systems based on urethane, the use thereof and substrates coated with them |
| CN108047645A (en) * | 2017-12-22 | 2018-05-18 | 合肥工业大学 | The melamine foams that a kind of isophorone diisocyanate using sealing end is prepared as curing agent |
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| JPS63125515A (en) * | 1986-11-14 | 1988-05-28 | Ohara Parajiumu Kagaku Kk | Production of water-soluble urethane resin |
| DE10024624A1 (en) * | 2000-05-18 | 2001-11-22 | Bayer Ag | Modified polyisocyanates, e.g. useful in coating compositions, obtained by reacting polyisocyanates with 2-(cyclohexylamino)ethanesulfonic acid and/or 3-(cyclohexylamino)propanesulfonic acid |
| CN102731749A (en) * | 2012-07-18 | 2012-10-17 | 上海材料研究所 | Solvent-free preparation method of sodium hydrogen sulfite closed-type waterborne polyurethane |
| CN104448232B (en) * | 2013-09-13 | 2017-12-15 | 万华化学集团股份有限公司 | Polyisocyanates that a kind of sulfamic acid is modified and its production and use |
| CN111154069A (en) * | 2020-01-15 | 2020-05-15 | 广州康狄夫环保科技有限公司 | Polyurethane curing agent, waterborne polyurethane, coating and preparation method and application thereof |
| CN114230764B (en) * | 2021-12-20 | 2023-06-13 | 嘉宝莉化工集团股份有限公司 | Water-based closed polyisocyanate curing agent and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101675132A (en) * | 2007-05-04 | 2010-03-17 | 巴斯福涂料股份公司 | Water-based two-layer coating systems based on urethane, the use thereof and substrates coated with them |
| CN108047645A (en) * | 2017-12-22 | 2018-05-18 | 合肥工业大学 | The melamine foams that a kind of isophorone diisocyanate using sealing end is prepared as curing agent |
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