Water-based polyisocyanate curing agent and preparation method thereof

Abstract

The invention relates to the technical field of preparation of polyisocyanate curing agents, and particularly discloses a water-based polyisocyanate curing agent and a preparation method thereof. The waterborne polyisocyanate curing agent is prepared from the following raw material components in parts by weight: 80 to 100 parts of polyisocyanate, 10 to 40 parts of methoxy polyethylene glycol acrylate, 5 to 20 parts of an amine compound, 5 to 20 parts of an acid compound and 0.01 to 0.1 part of a catalyst. According to the brand-new water-based polyisocyanate curing agent and the preparation method thereof, various alcohol ether solvents are not used in the preparation process of the water-based polyisocyanate curing agent, the VOC content is greatly reduced, and the solid content of the product is also improved; besides, compared with the existing polyisocyanate curing agent, the activation period of the waterborne polyisocyanate curing agent disclosed by the invention is remarkably or even greatly prolonged; and meanwhile, the hardness of the product is also remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of polyisocyanate curing agents, and particularly relates to an aqueous polyisocyanate curing agent and a preparation method thereof. Background Art

[0002] In the context of increasingly strict environmental regulations, the aqueous modification of polyisocyanates has become prominent in various application fields in recent years. Based on traditional solvent-based polyurethane curing agents, since there is no water in them, it can ensure the complete reaction of isocyanate groups with hydroxyl groups and form a coating film with high density and strong water resistance. After the current polyisocyanates are made aqueous, there are problems such as short pot life, poor compatibility, low crosslinking density, and poor water resistance. The research on aqueous polyurethane curing agents in China started relatively late. Enterprises only focus on cost control and patent protection, resulting in still being in the promotion stage and being difficult to sell on a large scale. Therefore, many research technicians have shown great interest in the aqueous modification of polyisocyanate curing agents.

[0003] Currently, there is little research on related aqueous cationic polyurethane curing agents. Most are first to synthesize trimers, then add chain extenders for chain extension, and finally quaternize to form salts. In this process, a large amount of toxic and harmful solvents are used, increasing the content of VOCs, and it is also difficult to obtain products with high solid content. Chinese Patent CN14656615A discloses an aqueous cationic polyurethane curing agent. This aqueous curing agent is composed of 50 - 60 parts by weight of isocyanate monomers, 10 - 20 parts by weight of diol ether solvents, 0.1 - 0.3 parts by weight of catalysts, 14 - 22 parts by weight of dihydroxy quaternary ammonium salt compounds, 20 - 30 parts by weight of water-soluble aprotic solvents, and 0.05 - 0.5 parts by weight of polymerization inhibitors. Although this patent can achieve the aqueous modification of polyurethane curing agents, and the hardness and water resistance are better than those of commercially available aqueous curing agents, alcohol ether solvents are still used in the reaction process, increasing the VOC content in the aqueous polyurethane curing agent. At the same time, the process time is long and relatively complex, and the manufacturing cost is high.

[0004] Therefore, in view of the current environmental protection requirements, providing a preparation method for an aqueous polyisocyanate that can reduce the VOC content has important application value; especially providing an aqueous polyisocyanate with a simple preparation process, low production cost, and / or long pot life has even more important application value. Summary of the Invention

[0005] In order to overcome at least one of the technical problems existing in the prior art, the present invention provides an aqueous polyisocyanate curing agent and a preparation method thereof.

[0006] The technical solution of the present invention is as follows: The present invention first provides an aqueous polyisocyanate curing agent, which comprises the following raw material components in parts by weight: 80 - 100 parts of polyisocyanate, 10 - 40 parts of methoxypolyethylene glycol acrylate, 5 - 20 parts of amine compound, 5 - 20 parts of acid compound, 0.01 - 0.1 part of catalyst.

[0007] Preferably, the polyisocyanate is selected from at least one of toluene diisocyanate trimer, toluene diisocyanate adduct, diphenylmethane diisocyanate trimer, diphenylmethane diisocyanate adduct, hexamethylene diisocyanate trimer, hexamethylene diisocyanate adduct, isophorone diisocyanate trimer, and isophorone diisocyanate adduct.

[0008] Preferably, the methoxypolyethylene glycol acrylate is selected from at least one of MPEG - 350 acrylate, MPEG - 400 acrylate, MPEG - 550 acrylate, MPEG - 600 acrylate, MPEG - 1000 acrylate, MPEG - 2000 acrylate, MPEG - 3400 acrylate, MPEG - 5000 acrylate, MPEG - 10000 acrylate, and MPEG - 20000 acrylate.

[0009] Preferably, the amine compound is selected from at least one of aniline, p - toluidine, 2 - methylcyclohexylamine, 1 - benzofuran - 2 - amine, aminoimidazole, aminopyridine, aminoquinoline, cyclohexylamine, and pentylamine.

[0010] Preferably, the acid compound is selected from at least one of glacial acetic acid, propionic acid, acetic acid, and acetic anhydride.

[0011] Preferably, the catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, tin naphthenate, lead naphthenate, cobalt naphthenate, dibutyltin maleate, dibutyltin diacetate, and benzyl glycidyl ether.

[0012] The present invention also provides a preparation method of the above - mentioned water - based polyisocyanate curing agent, which comprises the following steps: a) Mix methoxypolyethylene glycol acrylate, amine compound and catalyst, and stir - react; b) After the reaction in step a) is completed, add polyisocyanate and continue to react until the content of isocyanate group no longer changes; c) After step b) is completed, add acid compound for neutralization and quaternization to obtain the water - based polyisocyanate curing agent.

[0013] Preferably, the stirring reaction in step a) is carried out at 50 - 150 °C for 2 - 5 h.

[0014] Preferably, the temperature of the reaction in step b) is 100 - 150 °C.

[0015] Preferably, in step c), after step b) is completed, the temperature is controlled at 50-80°C, and an acid compound is added to carry out neutralization quaternization.

[0016] Beneficial effects: (1) The present invention provides a brand-new waterborne polyisocyanate curing agent and its preparation method. In the preparation process of this waterborne polyisocyanate curing agent, various alcohol ether solvents are not used, which greatly reduces the VOC content and also increases the solid content of the product.

[0017] (2) The present invention uses methoxypolyethylene glycol acrylate as a raw material to prepare a waterborne polyisocyanate curing agent. Compared with the existing polyisocyanate curing agents, its activation period has been significantly even greatly extended; at the same time, the hardness of the product has also been significantly improved.

[0018] (3) The waterborne polyisocyanate curing agent prepared by the present invention belongs to quaternary ammonium salt compounds, which have good water solubility, can eliminate the use of external emulsifiers and high shear forces, and greatly simplifies the preparation of waterborne curing agents; in addition, due to the presence of quaternary ammonium salts, the anti-corrosion and anti-mildew properties of the product are also improved, and the shelf life of the product is extended.

[0019] (4) The process route of the present invention is advanced, the preparation process is simple, the operability is strong, the reaction process is easy to control, and the quality of the prepared product is stable. Specific embodiments

[0020] The following further elaborates on the present invention in detail with specific embodiments, but the embodiments do not limit the present invention in any form.

[0021] Example 1 Preparation of waterborne polyisocyanate curing agent a) Put 12 parts of MPEG-550 acrylate, 6 parts of aminopyridine and 0.05 part of stannous octoate into a reaction kettle, start stirring and heat up to 120°C, and react for 4 h.

[0022] b) After the reaction in step a) is completed, add 80 parts of tolylene diisocyanate trimer, control the temperature at 100°C, and continue to react until the isocyanate group content no longer changes.

[0023] c) After step b) is completed, control the temperature at 60°C, add 5 parts of glacial acetic acid according to the formula amount to carry out neutralization quaternization to obtain waterborne polyisocyanate curing agent S1.

[0024] Example 2 Preparation of waterborne polyisocyanate curing agent a) Put 12 parts of MPEG-1000 acrylate, 6 parts of aminoimidazole and 0.05 part of stannous octoate into a reaction kettle, start stirring and heat up to 120 °C, and react for 3 h.

[0025] b) After the reaction in step a) is completed, add 80 parts of tolylene diisocyanate trimer, control the temperature at 120 °C, and continue to react until the isocyanate group content no longer changes.

[0026] c) After the completion of step b), control the temperature at 60 °C, add 5 parts of glacial acetic acid according to the formula amount for neutralization and quaternization to obtain the waterborne polyisocyanate curing agent S2.

[0027] Example 3 Preparation of waterborne polyisocyanate curing agent a) Put 12 parts of MPEG-1000 acrylate, 6 parts of aminoimidazole and 0.05 part of stannous octoate into a reaction kettle, start stirring and heat up to 120 °C, and react for 3 h.

[0028] b) After the reaction in step a) is completed, add 80 parts of hexamethylene diisocyanate trimer, control the temperature at 120 °C, and continue to react until the isocyanate group content no longer changes.

[0029] c) After the completion of step b), control the temperature at 60 °C, add 5 parts of glacial acetic acid according to the formula amount for neutralization and quaternization to obtain the waterborne polyisocyanate curing agent S3.

[0030] Example 4 Preparation of waterborne polyisocyanate curing agent a) Put 14 parts of MPEG-1000 acrylate, 8 parts of 2-methylcyclohexylamine and 0.05 part of stannous octoate into a reaction kettle, start stirring and heat up to 120 °C, and react for 3 h.

[0031] b) After the reaction in step a) is completed, add 90 parts of tolylene diisocyanate trimer, control the temperature at 100 °C, and continue to react until the isocyanate group content no longer changes.

[0032] c) After the completion of step b), control the temperature at 60 °C, add 5 parts of glacial acetic acid according to the formula amount for neutralization and quaternization to obtain the waterborne polyisocyanate curing agent S4.

[0033] Example 5 Preparation of waterborne polyisocyanate curing agent a) Put 20 parts of MPEG-5000 acrylate, 10 parts of 2-methylcyclohexylamine and 0.05 part of stannous octoate into a reaction kettle, start stirring and heat up to 120 °C, and react for 5 h.

[0034] b) After the reaction in step a) is completed, add 80 parts of hexamethylene diisocyanate trimer, control the temperature at 100 °C, and continue the reaction until the isocyanate group content no longer changes.

[0035] c) After the temperature control in step b) ends at 50 °C, add 5 parts of glacial acetic acid according to the formula amount for neutralization and quaternization to obtain the waterborne polyisocyanate curing agent S5.

[0036] Example 6 Preparation of waterborne polyisocyanate curing agent a) Put 14 parts of MPEG-550 acrylate, 10 parts of cyclohexylamine and 0.05 part of stannous octoate into the reaction kettle, start stirring and heat up to 120 °C, and react for 3 h.

[0037] b) After the reaction in step a) is completed, add 90 parts of toluene diisocyanate trimer, control the temperature at 120 °C, and continue the reaction until the isocyanate group content no longer changes.

[0038] c) After the temperature control in step b) ends at 60 °C, add 5 parts of propionic acid according to the formula amount for neutralization and quaternization to obtain the waterborne polyisocyanate curing agent S6.

[0039] The waterborne polyisocyanate curing agents S1-S6 (abbreviated as curing agents S1-S6 in Table 1) prepared in Examples 1-6 and the commercially available waterborne isocyanate curing agents S7-S9 were in the state in water (0.5%); and they were formulated into a two-component with the waterborne polyurethane emulsion according to a weight ratio of 1:5, and then their pot lives and pencil hardness were tested. The test results are shown in Table 1.

[0040] Table 1 Test results of various properties of the waterborne polyisocyanate curing agent of the present invention

[0041] As can be seen from Table 1, the curing agents S1-S6 and the comparative examples S7 and S9 can be stably dispersed in water, while the curing agent S8 cannot be stably dispersed in water.

[0042] The pot lives and pencil hardness of the curing agents S1-S9 formulated into a two-component with the polyurethane emulsion were tested. The pot lives and pencil hardness of Examples S1-S6 were better than those of the comparative examples S7-S9.

[0043] It can also be seen from Table 1 that the pot lives of the curing agents S1-S6 are significantly or even greatly longer than those of the curing agents S7-S9; at the same time, their pencil hardness is also better. This shows that: the present invention uses methoxypolyethylene glycol acrylate as a raw material to prepare a waterborne polyisocyanate curing agent. Compared with the existing polyisocyanate curing agents, its pot life has been significantly or even greatly extended; at the same time, the hardness of the product has been significantly improved.

[0044] It can also be seen from Table 1 that among the curing agents S1 to S6, the activation period of the curing agent S2 is significantly or even substantially longer than that of the curing agent S1 and the curing agents S3 - S6; this shows that: the specific selection of polyisocyanate, methoxypolyethylene glycol acrylate and amine compounds in the raw materials of the present invention has an important influence on the activation period of the waterborne polyisocyanate curing agent prepared; the above experimental results show that the waterborne polyisocyanate curing agent prepared by using toluene diisocyanate trimer, MPEG-1000 acrylate and aminoimidazole as raw materials has a significantly or even substantially longer activation period than the waterborne polyisocyanate curing agent prepared by using other polyisocyanates, methoxypolyethylene glycol acrylate and amine compounds as raw materials.

[0045] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made by using the content of the specification of the present invention, or directly or indirectly applied in the relevant technical field, shall be equally included in the patent protection scope of the present invention.

Claims

1. An aqueous polyisocyanate curing agent, characterized in that, The raw material components include the following parts by weight: 80 - 100 parts of polyisocyanate, 10 - 40 parts of methoxypolyethylene glycol acrylate, 5 - 20 parts of amine compound, 5 - 20 parts of acid compound, 0.01 - 0.1 part of catalyst.

2. The aqueous polyisocyanate curing agent according to claim 1, characterized in that, The polyisocyanate is selected from at least one of toluene diisocyanate trimer, toluene diisocyanate adduct, diphenylmethane diisocyanate trimer, diphenylmethane diisocyanate adduct, hexamethylene diisocyanate trimer, hexamethylene diisocyanate adduct, isophorone diisocyanate trimer, and isophorone diisocyanate adduct.

3. The aqueous polyisocyanate curing agent according to claim 1, characterized in that, The methoxypolyethylene glycol acrylate is selected from at least one of MPEG - 350 acrylate, MPEG - 400 acrylate, MPEG - 550 acrylate, MPEG - 600 acrylate, MPEG - 1000 acrylate, MPEG - 2000 acrylate, MPEG - 3400 acrylate, MPEG - 5000 acrylate, MPEG - 10000 acrylate, and MPEG - 20000 acrylate.

4. The aqueous polyisocyanate curing agent according to claim 1, characterized in that, The amine compound is selected from at least one of aniline, p - toluidine, 2 - methylcyclohexylamine, 1 - benzofuran - 2 - amine, aminoimidazole, aminopyridine, aminoquinoline, cyclohexylamine, and pentylamine.

5. The aqueous polyisocyanate curing agent according to claim 1, wherein The acid compound is selected from at least one of glacial acetic acid, propionic acid, acetic acid, and acetic anhydride.

6. The aqueous polyisocyanate curing agent according to claim 1, wherein The catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, tin naphthenate, lead naphthenate, cobalt naphthenate, dibutyltin maleate, dibutyltin diacetate, and benzyl glycidyl ether.

7. A method for preparing the aqueous polyisocyanate curing agent according to any one of claims 1 to 6, characterized in that, It includes the following steps: a) Mix methoxypolyethylene glycol acrylate, amine compound, and catalyst, and then stir and react. b) After the reaction in step a) is completed, add polyisocyanate and continue to react until the content of isocyanate groups no longer changes. c) After step b) ends, add acid compound for neutralization and quaternization to obtain an aqueous polyisocyanate curing agent.

8. The preparation method according to claim 7, characterized in that, In step a), the stirring reaction is carried out at 50 - 150 °C for 2 - 5 h.

9. The preparation method according to claim 7, characterized in that, In the reaction of step b), the temperature is 100 - 150 °C.

10. The preparation method according to claim 7, wherein In step c), after step b) ends, control the temperature at 50 - 80 °C, and add acid compound for neutralization and quaternization.

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