CN111763303A - Water-based blocked polyurethane curing agent and preparation method thereof - Google Patents
Water-based blocked polyurethane curing agent and preparation method thereof Download PDFInfo
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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
- C08G18/807—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with nitrogen containing compounds
- C08G18/8077—Oximes
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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
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/2805—Compounds having only one group containing active hydrogen
- C08G18/2815—Monohydroxy compounds
- C08G18/283—Compounds containing ether groups, e.g. oxyalkylated monohydroxy compounds
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- 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
- 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
- C08G18/8064—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with monohydroxy compounds
- C08G18/8067—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with monohydroxy compounds phenolic compounds
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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
- C08G18/807—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with nitrogen containing compounds
- C08G18/8074—Lactams
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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 relates to the field of chemical material preparation, and particularly relates to a water-based blocked polyurethane curing agent and a preparation method thereof. The waterborne blocked polyurethane curing agent is prepared from the following components in parts by weight: isocyanate polymer, monohydroxy polyether polyol and blocking agent. The water-based blocked polyurethane curing agent obtained by reacting the isocyanate polymer with the monohydroxy polyether polyol has the advantages of stable molecular weight, good water solubility, good compatibility with water-based resin, excellent paint film performance and long storage stability. The process can effectively control the molecular weight of the waterborne polyurethane, ensures the performance of the product, has simple and effective preparation method and low production cost, and can be used for large-scale production.
Description
Technical Field
The invention relates to the field of chemical material preparation, and particularly relates to a water-based blocked polyurethane curing agent and a preparation method thereof.
Background
With the stricter environmental regulations and the stricter standards in China, the traditional paint is gradually eliminated due to the requirement of using a large amount of Volatile Organic Compounds (VOC) in the application, and the water paint which can use water as a solvent or as a dispersion medium is increasingly regarded as important.
The water-based paint is mainly a two-component water-based paint, wherein the two components comprise the water-based paint serving as a film forming substance and a water-based polyurethane curing agent for improving the film coating performance of the water-based paint. The general aqueous polyurethane curing agent has high solid content, and when the curing agent is dissolved and dispersed in water, the initial viscosity is increased sharply, so that the aqueous polyurethane curing agent is agglomerated to generate particles. Therefore, before use, the waterborne polyurethane curing agent needs to be diluted by some hydrophilic solvents, so that the waterborne curing agent is easier to disperse in water, but the use of VOC is increased, and the waterborne polyurethane curing agent is not environment-friendly. Secondly, when the two-component water-based paint is used, isocyanate groups (NCO) in the water-based polyurethane curing agent can react with active groups in the water-based resin and can also react with water, and the reaction degree changes along with the temperature, so that the product performance is unstable. In addition, after the paint is prepared, because the use durations of different users are inconsistent, the stability, the smearing performance and the gloss of the two-component water-based paint are often greatly different, and therefore, the stable paint film effect cannot be ensured.
The blocked polyurethane curing agent is a polyurethane curing agent in which high-activity NCO is protected in advance. The addition-elimination mechanism is utilized, that is, unreacted NCO groups in the curing agent are blocked by grafting, and then the blocking agent is removed at high temperature. The blocked polyurethane curing agent can effectively solve the problem of reaction of NCO and water in the curing agent, but how to uniformly disperse the blocked polyurethane curing agent into water has good stability, and is difficult and challenging for effective application of the blocked polyurethane curing agent.
The development of a water-based blocked polyurethane curing agent having good water dispersibility and stability is effective in solving the above problems, but few studies have been made on the water-based blocked polyurethane curing agent. In patent CN110423323A, a preparation method of a water-based blocked polyurethane curing agent is to block NCO groups of isocyanate polymer part with a blocking agent, and then to make the blocked NCO groups water-based with grafted hydrophilic groups. The method can not accurately ensure the number of NCO groups in the polymer after being blocked, thereby causing the number of grafted hydrophilic groups to be inaccurately ensured. If the blocked NCO groups are too many, the number of the residual NCO groups grafted with hydrophilic groups is not enough, the dispersibility and the compatibility with the aqueous resin of the aqueous polyurethane curing agent are reduced, and the performance of the final paint film is influenced. If the NCO groups blocked by the blocking agent are too few, the grafted hydrophilic group can not completely react the NCO to be reacted, so that the stability of the product can not be ensured. Patent CN108424502A uses dihydroxy compound to graft hydrophilic group, because two hydroxyl groups in dihydroxy compound react with NCO in polyurethane curing agent when isocyanate polymer is grafted, it is impossible to control the molecular weight of the reacted polymer, and because only one hydroxyl group in each molecule can be grafted, the molecular weight of the polymer can be controlled, and the size of the molecular weight directly affects the water dispersibility of polyurethane curing agent.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a water-based blocked polyurethane curing agent and a preparation method thereof. The water-based blocked polyurethane curing agent obtained by reacting the isocyanate polymer with the monohydroxy polyether polyol has the advantages of stable molecular weight, good water solubility, good compatibility with water-based resin, excellent paint film performance and long storage stability. The process can effectively control the molecular weight of the waterborne polyurethane, ensures the performance of the product, has simple and effective preparation method and low production cost, and can be used for large-scale production.
The technical scheme adopted by the invention is as follows:
the water-based blocked polyurethane curing agent is prepared from the following components: isocyanate polymer, monohydroxy polyether polyol and blocking agent.
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8-12 parts of isocyanate polymer, 0.5-3 parts of monohydroxy polyether polyol and 1-5 parts of sealant.
According to the technical scheme of the invention, the ratio of the isocyanate polymer to the monohydroxy polyether polyol has an important influence on the performance of the water-based blocked polyurethane curing agent. If the proportion of the monohydroxy polyether polyol to the isocyanate polymer is low, the water solubility of the aqueous blocked polyurethane curing agent cannot be improved; and the proportion of the monohydroxy polyether polyol to the isocyanate polymer is too high, the water resistance of the water-based blocked polyurethane curing agent is reduced, and the number of the effective NCO groups which can be blocked is reduced, so that the effect of improving a paint film cannot be achieved.
Preferably, the isocyanate polymer is one or more of hexamethylene diisocyanate polymer, isophorone diisocyanate polymer and dicyclohexylmethane diisocyanate polymer.
Further preferably, the hexamethylene diisocyanate multimer is a hexamethylene diisocyanate trimer; the isophorone diisocyanate polymer is isophorone diisocyanate trimer; the dicyclohexylmethane diisocyanate polymer is dicyclohexylmethane diisocyanate trimer.
Preferably, the monohydroxy polyether polyol is one or two of monohydroxy polyethylene glycol and monohydroxy polypropylene glycol.
According to the technical scheme, the selected hydrophilic group is monohydroxy polyether polyol. The monohydroxypolyether polyols contain a large number of ether linkages. In the synthesis, only a small amount of polyether polyol needs to be grafted to achieve good water dispersibility. This makes it possible, on the one hand, to reduce the amount of NCO groups which react in the isocyanate polymer and thus to ensure the effective NCO group content in the end product. In addition, one end of the hydroxyl of the polyether polyol is sealed, so that only one hydroxyl is contained in one large polyether molecule, the grafting is stable in the reaction, the problem of implosion cannot occur, the molecular weight of the product is easy to control, and the product is more stable.
Further preferably, the molar mass of the monohydroxy polyether polyol is 300-2000 g/mol.
According to the technical scheme of the invention, the molar mass is used to represent the molecular weight of the monohydroxy polyether polyol, and the water solubility of the water-based blocked polyurethane curing agent can be effectively ensured by using the monohydroxy polyether polyol of 300-2000 g/mol. The monohydroxypolyether polyols having too low a molecular weight lead to poor water dispersibility and storage stability of the grafted aqueous isocyanate polymers owing to the insufficient number of ether bonds. The monohydroxy polyether polyol has an excessively large molecular weight, and the compatibility with the aqueous resin is deteriorated, resulting in a reduced paint film effect. In addition, the molecular weight is too large, which also increases the viscosity of the water-based blocked polyurethane curing agent, and is not favorable for improving the water solubility of the product.
Further preferably, the molar mass of the monohydroxy polyether polyol is 300-500 g/mol.
Preferably, the blocking agent is one or more of methyl ethyl ketoxime, methyl pyrazole, caprolactam, diethyl malonate and phenol.
Preferably, the water-based blocked polyurethane has an effective NCO content of 8-14%.
In the technical scheme of the invention, the effective NCO content is 8-14% by selecting raw materials, proportioning reactants and controlling reaction conditions. The effective NCO group is a basic index for evaluating the properties of products. High effective NCO group and excellent performance.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) adding a monohydroxy polyether polyol to the isocyanate polymer; the reaction gives an aqueous isocyanate polymer.
(2) And adding a blocking agent into the water-based isocyanate polymer to react to obtain the water-based blocked polyurethane curing agent.
Preferably, the reaction of the isocyanate multimer with the monohydroxypolyether polyol in step (1) is carried out under the protection of an inert gas.
Further preferably, the inert gas is nitrogen.
Preferably, the monohydroxy polyether polyol is added dropwise at a temperature of 50-80 ℃ for 0.5-2 hours; then reacting for 2-5 hours at the temperature of 50-80 ℃ to obtain the water-based isocyanate polymer.
Preferably, the sealant is added in a dropwise manner, and the dropwise adding time is 1-5 hours; then reacting for 2-5 hours at the temperature of 80-100 ℃ to obtain the water-based blocked polyurethane curing agent.
According to the technical scheme of the invention, the dropwise addition of the feeding material, particularly the dropwise addition of the monohydroxy polyether polyol can enable the reaction to be stable. The direct one-time feeding easily causes uneven molecular weight of the product. The technicians in the field can adjust the specific dropping speed and volume according to the material quantity and the dropping time and keep stable dropping.
According to the technical scheme of the invention, the reaction condition of the monohydroxy polyether polyol is critical, and due to the reaction characteristic of the monohydroxy polyether polyol, the dropping temperature needs to be additionally controlled, so that the reaction stability and the reaction efficiency can be controlled. The dripping temperature is too low, so that the reaction efficiency is low and the grafting effect is poor; if the dropping temperature is too high, the reaction is too fast and the molecular weight is not uniform.
According to the technical scheme of the invention, a person skilled in the art can add a certain amount of water to control the solid content of the water-based blocked polyurethane curing agent to be 40-50% according to actual needs.
The invention has the beneficial effects that:
(1) the water-based blocked polyurethane curing agent obtained by reacting the isocyanate polymer with the monohydroxy polyether polyol has the advantages of good water solubility, good compatibility with water-based resin, excellent paint film performance, long storage stability and good use effect. The grafted monohydroxy polyether polyol has uniform molecular weight, and the adopted raw material contains monohydroxy and only one grafting group, and simultaneously, the dripping process is adopted, so that the molecular weight of the product is ensured to be stable.
(2) The water-based blocked polyurethane curing agent disclosed by the invention is low in deblocking temperature and short in deblocking time, and can be widely applied to water-based baking varnish and water-based glue.
(3) The preparation method has simple process and low equipment requirement, and can be used for large-scale production and preparation.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments.
Example 1
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8 parts of hexamethylene diisocyanate trimer, 2 parts of monohydroxy polyethylene glycol and 4.3 parts of methyl ethyl ketoxime; wherein the molar mass of the monohydroxy polyethylene glycol is 300 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 60 ℃, dropwise adding monohydroxy polyethylene glycol into hexamethylene diisocyanate tripolymer in a reaction kettle for 1 hour; the reaction was carried out at 60 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 1 hour, and reacting for 5 hours at the temperature of 80 ℃ to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 13.4%.
Example 2
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 10 parts of hexamethylene diisocyanate trimer, 1.8 parts of monohydroxypropylene glycol and 4.7 parts of methylpyrazole; wherein the molar mass of the monohydroxypolypropylene glycol is 500 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 65 ℃, dropwise adding monohydroxypropylene glycol into hexamethylene diisocyanate trimer in a reaction kettle for 0.5 hour; the reaction was carried out at 70 ℃ for 2 hours to obtain an aqueous isocyanate polymer.
(2) And (3) dropwise adding methylpyrazole into the water-based isocyanate polymer for 2 hours, and reacting at the temperature of 85 ℃ for 5 hours to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 13.8 percent.
Example 3
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 10 parts of hexamethylene diisocyanate trimer, 1.5 parts of monohydroxy polyethylene glycol and 1 part of caprolactam; wherein the molar mass of the monohydroxy polyethylene glycol is 500 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 50 ℃, dropwise adding monohydroxy polyethylene glycol into hexamethylene diisocyanate tripolymer in a reaction kettle for 2 hours; the reaction was carried out at 50 ℃ for 5 hours to obtain an aqueous isocyanate polymer.
(2) And (3) dropwise adding caprolactam into the water-based isocyanate polymer for 1 hour, and reacting at the temperature of 85 ℃ for 3 hours to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 13.2 percent.
Example 4
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 10 parts of isophorone diisocyanate trimer, 0.5 part of monohydroxy polyethylene glycol and 2 parts of methyl ethyl ketoxime; wherein the molar mass of the monohydroxy polyethylene glycol is 350 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 70 ℃, dropwise adding monohydroxy polyethylene glycol into isophorone diisocyanate tripolymer in a reaction kettle for 2 hours; the reaction was carried out at 70 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 2 hours, and reacting at the temperature of 90 ℃ for 2.5 hours to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 9 percent.
Example 5
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 12 parts of dicyclohexylmethane diisocyanate trimer, 3 parts of monohydroxypropylene glycol and 5 parts of phenol; wherein the molar mass of the monohydroxypolypropylene glycol is 500 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 80 ℃, dropwise adding monohydroxypropylene glycol into dicyclohexyl methane diisocyanate tripolymer in a reaction kettle for 2 hours; the reaction was carried out at 80 ℃ for 2 hours to obtain an aqueous isocyanate polymer.
(2) And (3) dropwise adding phenol into the water-based isocyanate polymer for 5 hours, and reacting at the temperature of 95 ℃ for 2 hours to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 8.4%.
Example 6
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 5 parts of isophorone diisocyanate trimer, 5 parts of hexamethylene diisocyanate trimer, 1.2 parts of monohydroxypropylene glycol and 2 parts of diethyl malonate; wherein the molar mass of the monohydroxypolypropylene glycol is 2000 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 70 ℃, dropwise adding monohydroxypropylene glycol into isophorone diisocyanate tripolymer and hexamethylene diisocyanate tripolymer in a reaction kettle for 0.5 hour; the reaction was carried out at 70 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (3) dropwise adding diethyl malonate into the water-based isocyanate polymer for 1 hour, and reacting at the temperature of 100 ℃ for 2 hours to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 10.8 percent.
Comparative example 1 (less than 0.5 parts by weight of monohydroxypolyethylene glycol compared with example 1)
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8 parts of hexamethylene diisocyanate trimer, 0.3 part of monohydroxy polyethylene glycol and 4.3 parts of methyl ethyl ketoxime; wherein the molar mass of the monohydroxy polyethylene glycol is 300 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 60 ℃, dropwise adding monohydroxy polyethylene glycol into hexamethylene diisocyanate tripolymer in a reaction kettle for 1 hour; the reaction was carried out at 60 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 1 hour, and reacting for 5 hours at the temperature of 80 ℃ to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 14.8 percent.
Comparative example 2 (more than 3 parts by weight of monohydroxypolyethylene glycol compared with example 1)
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8 parts of hexamethylene diisocyanate trimer, 5 parts of monohydroxy polyethylene glycol and 4.3 parts of methyl ethyl ketoxime; wherein the molar mass of the monohydroxy polyethylene glycol is 300 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 60 ℃, dropwise adding monohydroxy polyethylene glycol into hexamethylene diisocyanate tripolymer in a reaction kettle for 1 hour; the reaction was carried out at 60 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 1 hour, and reacting for 5 hours at the temperature of 80 ℃ to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 9.7 percent.
Comparative example 3 (comparison with example 1, using bishydroxy polyethylene glycol)
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8 parts of hexamethylene diisocyanate trimer, 2 parts of dihydroxyl polyethylene glycol and 4.3 parts of methyl ethyl ketoxime; wherein the molar mass of the dihydroxyl polyethylene glycol is 300 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 60 ℃, dropwise adding monohydroxy polyethylene glycol into hexamethylene diisocyanate tripolymer in a reaction kettle for 1 hour; the reaction was carried out at 60 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 1 hour, and reacting for 5 hours at the temperature of 80 ℃ to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 8.2 percent.
Comparative example 4 (comparison with example 1, using toluene diisocyanate trimer)
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8 parts of toluene diisocyanate trimer, 2 parts of monohydroxy polyethylene glycol and 4.3 parts of methyl ethyl ketoxime; wherein the molar mass of the monohydroxy polyethylene glycol is 300 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen at the temperature of 60 ℃, dropwise adding monohydroxy polyethylene glycol into the toluene diisocyanate tripolymer in a reaction kettle for 1 hour; the reaction was carried out at 60 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 1 hour, and reacting for 5 hours at the temperature of 80 ℃ to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 7.6 percent.
Comparative example 5 (in comparison with example 1, the temperature of dropwise addition of monohydroxypolyethylene glycol in step 1 was 25 ℃ C.)
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8 parts of hexamethylene diisocyanate trimer, 2 parts of monohydroxy polyethylene glycol and 4.3 parts of methyl ethyl ketoxime; wherein the molar mass of the monohydroxy polyethylene glycol is 300 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 25 ℃, dropwise adding monohydroxy polyethylene glycol into hexamethylene diisocyanate tripolymer in a reaction kettle for 1 hour; the reaction was carried out at 60 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 1 hour, and reacting for 5 hours at the temperature of 80 ℃ to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 14.8 percent.
Comparative example 6 (temperature of dropping monohydroxypolyethylene glycol in step 1 was 100 ℃ C. compared with example 1)
The water-based blocked polyurethane curing agent is prepared from the following components in parts by weight: 8 parts of hexamethylene diisocyanate trimer, 2 parts of monohydroxy polyethylene glycol and 4.3 parts of methyl ethyl ketoxime; wherein the molar mass of the monohydroxy polyethylene glycol is 300 g/mol.
The preparation method of the waterborne blocked polyurethane curing agent comprises the following steps:
(1) under the protection of nitrogen and at the temperature of 100 ℃, dropwise adding monohydroxy polyethylene glycol into hexamethylene diisocyanate trimer in a reaction kettle for 1 hour; the reaction was carried out at 60 ℃ for 4 hours to obtain an aqueous isocyanate polymer.
(2) And (2) dropwise adding methyl ethyl ketoxime into the water-based isocyanate polymer for 1 hour, and reacting for 5 hours at the temperature of 80 ℃ to obtain the water-based blocked polyurethane curing agent.
Wherein the blocked effective NCO content of the waterborne blocked polyurethane curing agent is 8.6 percent.
Examples of the experiments
The performance of the aqueous blocked polyurethane curing agent of the present invention and the aqueous blocked polyurethane curing agents of comparative examples 1 to 6 was tested under the same test conditions, and the test results are shown in table 1.
TABLE 1
As can be seen from the table above, compared with the comparative example, the waterborne blocked polyurethane curing agent disclosed by the invention has the advantages of good stability, appropriate deblocking conditions and good comprehensive performance, can be effectively applied to waterborne resin and has a certain application prospect.
Claims (10)
1. The water-based blocked polyurethane curing agent is characterized by being prepared from the following components: isocyanate polymer, monohydroxy polyether polyol and blocking agent.
2. The water-based blocked polyurethane curing agent is characterized by being prepared from the following components in parts by weight: 8-12 parts of isocyanate polymer, 0.5-3 parts of monohydroxy polyether polyol and 1-5 parts of sealant.
3. The aqueous blocked polyurethane curing agent according to claim 1 or 2, wherein the isocyanate polymer is one or more of hexamethylene diisocyanate polymer, isophorone diisocyanate polymer, and dicyclohexyltoluene diisocyanate polymer.
4. The waterborne blocked polyurethane curing agent according to claim 3, wherein the hexamethylene diisocyanate polymer is a hexamethylene diisocyanate trimer; the isophorone diisocyanate polymer is isophorone diisocyanate trimer; the dicyclohexylmethane diisocyanate polymer is dicyclohexylmethane diisocyanate trimer.
5. The waterborne blocked polyurethane curing agent of claim 1, wherein the monohydroxy polyether polyol is one or both of monohydroxy polyethylene glycol and monohydroxy polypropylene glycol.
6. The waterborne blocked polyurethane curing agent of claim 5, wherein the monohydroxy polyether polyol has a molar mass of 300-2000 g/mol.
7. The waterborne blocking polyurethane curing agent of claim 1, wherein the blocking agent is one or more of methyl ethyl ketoxime, methyl pyrazole, caprolactam, diethyl malonate and phenol.
8. The method for preparing the aqueous blocked polyurethane curing agent according to any one of claims 1 to 7, comprising the steps of:
(1) adding a monohydroxy polyether polyol to the isocyanate polymer; the reaction gives an aqueous isocyanate polymer.
(2) And adding a blocking agent into the water-based isocyanate polymer to react to obtain the water-based blocked polyurethane curing agent.
9. The method of preparing the waterborne blocked polyurethane curing agent according to claim 8, wherein the reaction of the isocyanate polymer with the monohydroxy polyether polyol in the step (1) is carried out under the protection of an inert gas.
10. The method for preparing the waterborne blocked polyurethane curing agent according to claim 8, wherein in the step (1), the monohydroxy polyether polyol is added dropwise at a temperature of 50 to 80 ℃ for 0.5 to 2 hours; then reacting for 2-5 hours at the temperature of 50-80 ℃ to obtain a water-based isocyanate polymer; in the step (2), the sealant is added in a dropwise manner, wherein the dropwise adding time is 1-5 hours; then reacting for 2-5 hours at the temperature of 80-100 ℃ to obtain the water-based blocked polyurethane curing agent.
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| CN114410174A (en) * | 2022-02-24 | 2022-04-29 | 郑州中科新兴产业技术研究院 | High-performance water-based acrylic polyurethane coating and preparation method thereof |
| WO2023206758A1 (en) * | 2022-04-24 | 2023-11-02 | 苏州市陆氏新材料有限公司 | Heating cross-linking polyurethane adhesive, and polyurethane adhesive film and preparation method therefor |
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