Organic silicon modified polyurethane waterproof coating and preparation method thereof

Abstract

The invention belongs to the technical field of polyurethane coatings, and discloses an organosilicon modified polyurethane waterproof coating and a preparation method thereof. The preparation method comprises the following steps: carrying out heating and stirring reaction on hydroxyl-terminated polybutadiene and hydrogen-terminated silicone oil in a molar ratio of (1.8-2.2): 1 in the presence of an organic solvent and a vinyl platinum catalyst to obtain an organic silicon modified hydroxyl-terminated polybutadiene solution; then adding polyol and a filler, mixing, carrying out vacuum dehydration at 100-120 DEG C, cooling to 70-80 DEG C, adding polyisocyanate, carrying out heat preservation and prepolymerization reaction for 2-4 hours, cooling to 50-60 DEG C, adding a catalyst, continuing stirring and reacting for 0.5-1 hour, cooling to room temperature, filling nitrogen into the reaction mixture, and sealing and packaging to obtain the organic silicon modified polyurethane waterproof coating. The organic silicon modified hydroxyl-terminated polybutadiene is adopted for copolymerization modification, so that the flexibility, the water resistance, the heat resistance and the weather resistance of the polyurethane waterproof coating can be remarkably improved, and relatively high strength can be kept.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane coatings, and in particular relates to an organosilicon-modified polyurethane waterproof coating and a preparation method thereof. Background Art

[0002] Polyurethane waterproof coatings are widely used in building waterproofing due to their excellent mechanical properties and strong bonding with concrete. Based on their composition and curing mechanism, polyurethane waterproof coatings are primarily divided into two categories: one-component polyurethane waterproof coatings and multi-component polyurethane waterproof coatings. Because multi-component polyurethane waterproof coatings require specific proportions during on-site construction, uncontrollable factors such as inaccurate batching and uneven mixing can affect construction quality, resulting in poor controllability. One-component polyurethane waterproof coatings, on the other hand, consist of a single component and are ready for use, requiring no mixing or mixing. They are reliable and have gained widespread application.

[0003] One-component polyurethane waterproof coatings are generally made from an isocyanate-containing prepolymer, mixed with catalysts, functional additives, fillers, solvents, etc. However, the flexibility, water resistance, and weather resistance of conventional one-component polyurethane waterproof coatings need further improvement.

[0004] Patent publication number CN 113444439 B describes a silicone-fluorine-modified one-component polyurethane waterproof coating. It uses specific silicone and fluorine-modifying materials to modify the polyurethane coating, achieving enhanced toughness and strengthening. Fluorocarbon side chains also impart hydrophobicity and oleophobicity to the polyurethane resin, significantly improving its weather resistance. This patent utilizes silicone (organosilane end-capping agent) and organofluorine (fluorocarbon alcohol) in the cross-linking reaction. However, the reactivity of the organosilane end-capping agent and fluorocarbon alcohol with polyether and isocyanate varies significantly, resulting in poor reaction controllability. Patent publication number CN 114213618 A describes a hydroxyl-terminated liquid polybutadiene rubber-modified waterborne polyurethane resin. The hydroxyl-terminated liquid polybutadiene rubber is chemically bonded to the polyurethane resin, resulting in a stable structure. The polyurethane resin exhibits excellent sag resistance, impact resistance, high cross-link density, and flexibility. However, the introduction of polybutadiene rubber alone adversely affects the strength, heat resistance, and weather resistance of the polyurethane resin. Summary of the Invention

[0005] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a silicone-modified polyurethane waterproof coating.

[0006] Another object of the present invention is to provide a silicone-modified polyurethane waterproof coating prepared by the above method.

[0007] The purpose of the present invention is achieved through the following technical solutions: A preparation method of a silicone-modified polyurethane waterproof coating, comprising the following preparation steps: (1) Preparation of silicone-modified hydroxyl-terminated polybutadiene: The hydroxyl-terminated polybutadiene and the hydroxyl-terminated silicone oil are added into an organic solvent in a molar ratio of 1.8-2.2:1, uniformly dissolved, then a vinyl platinum catalyst (platinum(0)-divinyltetramethyldisiloxane complex) is added, heated and stirred to react, to obtain a silicone-modified hydroxyl-terminated polybutadiene solution; (2) Preparation of the silicone-modified polyurethane waterproof coating: The silicone-modified hydroxyl-terminated polybutadiene solution of step (1) is mixed with polyols and fillers, then vacuum dehydration is performed at 100-120°C, then the temperature is lowered to 70-80°C, polyisocyanate is added for pre-polymerization reaction for 2-4h, then the temperature is lowered to 50-60°C, a catalyst is added for continued stirring reaction for 0.5-1h, and then the reaction mixture is cooled to room temperature, sealed and packaged under nitrogen, to obtain the silicone-modified polyurethane waterproof coating.

[0008] The hydroxyl-terminated polybutadiene in step (1) has a hydroxyl value of 0.5-2mmol / g and an average molecular weight of 1000-4000.

[0009] The hydroxyl-terminated polybutadiene is a raw material commonly commercially available in the art, such as Yincui POLYVEST HT, and its molecular structure formula is as shown below: x=1,2-double bond [%]: ~22%; y=1,4-trans double bond [%]: ~58%; z=1,4-cis double bond [%]: ~20%.

[0010] The hydroxyl-terminated silicone oil in step (1) has a hydrogen content of 0.05-0.2wt% and an average molecular weight of 1000-4000.

[0011] The hydroxyl-terminated silicone oil is a raw material commonly commercially available in the art, and its structure formula is as shown below: .

[0012] In the present application, the molar ratio of the hydroxyl-terminated polybutadiene to the hydroxyl-terminated silicone oil is controlled to be close to 2:1 (1.8-2.2:1), and the main reaction formula is as follows: .

[0013] By introducing the cross-linked polysiloxane chain with high weather resistance, high heat resistance, high hydrophobicity and good flexibility into the hydroxyl-terminated polybutadiene molecule, the strength, water resistance and flexibility of the obtained polyurethane coating can be improved, and the adverse effects of the polybutadiene molecular chain on the heat resistance, weather resistance and strength can be reduced.

[0014] The organic solvent in step (1) is any one of toluene, xylene, acetone, ethyl acetate, butyl acetate, tetrahydrofuran or a mixed solvent of at least two of them; the amount of the organic solvent is such that the solid content of the finally obtained silicone-modified polyurethane waterproof coating is ≥ 85%.

[0015] The temperature of the heating and stirring reaction in step (1) is 70-90℃, and the time is 3-8h.

[0016] The solid content of the silicone-modified hydroxyl-terminated polybutadiene solution in step (1) is 30%-60%.

[0017] The polyol in step (2) is a mixture of a macromolecular diol with an average molecular weight of 500-2000 and a small molecular diol in a molar ratio of 1:1-2; the macromolecular diol is at least one of polycarbonate diol, polyester diol (such as polycaprolactone diol), polyether diol (such as polytetrahydrofuran), and the small molecular diol is at least one of ethylene glycol, propylene glycol and butanediol.

[0018] The amount of the polyol added in step (2) is 3-10 times the solid content of the silicone-modified hydroxyl-terminated polybutadiene solution.

[0019] The filler in step (2) is calcium carbonate, and the amount of the filler added is 5%-30% of the mass of the polyol.

[0020] The polyisocyanate in step (2) is toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenyl methane diisocyanate (MDI), hexamethylene diisocyanate (HDI) or dicyclohexyl methane diisocyanate (HMDI), and the amount of the polyisocyanate added is 1.2-1.5 times the molar amount of the polyol.

[0021] The catalyst in step (2) is dibutyl tin dilaurate, and the amount of the catalyst added is 0.5%-1% of the mass of the polyol.

[0022] A silicone-modified polyurethane waterproof coating is prepared by the above method.

[0023] Compared with the prior art, the silicone-modified polyurethane waterproof coating has the following advantages: The silicone-modified hydroxyl-terminated polybutadiene prepared by the specific method is used to copolymerize and modify the polyurethane waterproof coating, the introduction of the polybutadiene chain segment improves the flexibility and water resistance of the polyurethane waterproof coating, and the further crosslinking of the polybutadiene chain segment by the polysiloxane chain with high weather resistance, high heat resistance, high hydrophobicity and good flexibility can simultaneously improve the strength, water resistance and flexibility of the obtained polyurethane coating, and improve the adverse effects of the polybutadiene molecular chain on the heat resistance, weather resistance and strength. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto. Example

[0025] A method for preparing a silicone-modified polyurethane waterproof coating comprises the following steps: (1) Preparation of silicone-modified hydroxy-terminated polybutadiene: Hydroxyl-terminated polybutadiene (Evonik POLYVEST HT, hydroxyl value of 0.67 mmol / g, molecular weight ~3000) and hydrogen-terminated silicone oil (hydrogen content of 0.09 wt%, molecular weight ~2200) were added in a molar ratio of 2:1 into a xylene / acetone mixed solvent with a mass ratio of 1:1 and mixed and dissolved evenly. Then, 0.01% of the system mass of vinyl platinum catalyst (platinum (0)-divinyltetramethyldisiloxane complex) was added and heated to 80°C with stirring for 5 hours. The silicon-hydrogen content in the product was measured and no detection was found, indicating that the reaction was complete, thereby obtaining a silicone-modified hydroxyl-terminated polybutadiene solution with a solid content of 40%.

[0026] (2) Preparation of silicone-modified polyurethane waterproof coating: 100 parts by mass of the organosilicon-modified hydroxy-terminated polybutadiene solution of step (1) was added to a reactor, and then 180 parts by mass of polycarbonate diol (commercially available, hydroxyl value 100-120 mgKOH / g, molecular weight ~1000), 20 parts by mass of 1,2-propylene glycol and 36 parts by mass of nano-calcium carbonate were added and mixed, and then vacuum dehydrated at 100-120°C for 2h, and then cooled to 70-80°C, and 124 parts by mass of IPDI was added and prepolymerized for 3h, and then cooled to 50-60°C, and 1.5 parts by mass of dibutyltin dilaurate catalyst was added and stirred for 1h until the viscosity stabilized, and then cooled to room temperature. The reaction mixture was nitrogen-filled and sealed to obtain an organosilicon-modified polyurethane waterproof coating. Example

[0027] A method for preparing a silicone-modified polyurethane waterproof coating comprises the following steps: (1) Preparation of silicone-modified hydroxy-terminated polybutadiene: The hydroxyl-terminated polybutadiene (Yingchuang POLYVEST HT, hydroxyl value 0.67 mmol / g, molecular weight ~ 3000) and the hydrogen-terminated silicone oil (hydrogen content 0.05 wt%, molecular weight ~ 4000) are mixed and dissolved uniformly in a mixed solvent of xylene / acetone in a mass ratio of 1:1 at a molar ratio of 1.8:1, then 0.01% of a vinyl platinum catalyst (platinum(0)-divinyltetramethyldisiloxane complex) by mass of the system is added, heated to 75°C and stirred for 8h. The hydrogen content in the product is not detected, indicating that the reaction is complete. An organic silicon modified hydroxyl-terminated polybutadiene solution with a solid content of 30% is obtained.

[0028] (2) Preparation of silicone-modified polyurethane waterproof coating: Take 100 mass parts of the silicone-modified hydroxyl-terminated polybutadiene solution of step (1) and add it to a reaction kettle, then mix 150 mass parts of polycaprolactone diol (commercially available, PCL-500), 50 mass parts of 1,4-butanediol and 50 parts of nano calcium carbonate, vacuum dehydrate at 100-120°C for 2h, then cool to 70-80°C, add 200 mass parts of TDI, pre-polymerize for 3h, then cool to 50-60°C, add 1 mass part of dibutyltin dilaurate catalyst, continue to stir for 0.5h until the viscosity is stable, cool to room temperature, seal and package the reaction mixture under nitrogen, and obtain a silicone-modified polyurethane waterproof coating. Example

[0029] A method for preparing a silicone-modified polyurethane waterproof coating, comprising the following preparation steps: (1) Preparation of silicone-modified hydroxyl-terminated polybutadiene: The hydroxyl-terminated polybutadiene (Yingchuang POLYVEST HT, hydroxyl value 0.67 mmol / g, molecular weight ~ 3000) and the hydrogen-terminated silicone oil (hydrogen content 0.2 wt%, molecular weight ~ 1000) are mixed and dissolved uniformly in a mixed solvent of xylene / acetone in a mass ratio of 1:1 at a molar ratio of 2.2:1, then 0.01% of a vinyl platinum catalyst (platinum(0)-divinyltetramethyldisiloxane complex) by mass of the system is added, heated to 90°C and stirred for 3h. The hydrogen content in the product is not detected, indicating that the reaction is complete. An organic silicon modified hydroxyl-terminated polybutadiene solution with a solid content of 60% is obtained.

[0030] (2) Preparation of silicone-modified polyurethane waterproof coating: Take 100 parts by mass of the silicone-modified hydroxyl-terminated polybutadiene solution of step (1) into the reaction kettle, then add 200 parts by mass of polytetrahydrofuran (commercially available, hydroxyl value 55-58 mgKOH / g, molecular weight ~2000), 12 parts by mass of ethylene glycol and 12 parts of nano calcium carbonate, mix, then vacuum dehydrate at 100-120°C for 2h, then cool to 70-80°C, add 72 parts by mass of HDI, and pre-polymerize for 3h, then cool to 50-60°C, add 2 parts by mass of dibutyltin dilaurate catalyst, continue to stir for 1h until the viscosity is stable, cool to room temperature, seal the reaction mixture under nitrogen, and package to obtain a silicone-modified polyurethane waterproof coating.

[0031] Comparative Example 1 A method for preparing a polyurethane waterproof coating, compared with Example 1, uses polycarbonate diol with about equal molar hydroxyl content to replace silicone-modified hydroxyl-terminated polybutadiene, including the following preparation steps: Take 60 parts by mass of a mixture of xylene / acetone with a mass ratio of 1:1 into the reaction kettle, then add 190 parts by mass of polycarbonate diol (commercially available, hydroxyl value 100-120 mgKOH / g, molecular weight ~1000), 20 parts by mass of 1,2-propanediol and 36 parts of nano calcium carbonate, mix, then vacuum dehydrate at 100-120°C for 2h, then cool to 70-80°C, add 124 parts by mass of IPDI, and pre-polymerize for 3h, then cool to 50-60°C, add 1.5 parts by mass of dibutyltin dilaurate catalyst, continue to stir for 1h until the viscosity is stable, cool to room temperature, seal the reaction mixture under nitrogen, and package to obtain a polyurethane waterproof coating.

[0032] Comparative Example 2 A method for preparing a polybutadiene-modified polyurethane waterproof coating, compared with Example 1, uses hydroxyl-terminated polybutadiene with about equal molar hydroxyl content to replace silicone-modified hydroxyl-terminated polybutadiene, including the following preparation steps: (1) Add hydroxyl-terminated polybutadiene (Yingchuang POLYVEST HT, hydroxyl value 0.67 mmol / g, molecular weight ~3000) into a mixture of xylene / acetone with a mass ratio of 1:1, mix and dissolve uniformly to obtain a hydroxyl-terminated polybutadiene solution with a solid content of 30%.

[0033] (2) 100 parts by mass of the hydroxyl-terminated polybutadiene solution of step (1) is added to a reaction kettle, then 180 parts by mass of polycarbonate diol (commercially available, hydroxyl value 100-120 mgKOH / g, molecular weight ~1000), 20 parts by mass of 1,2-propanediol and 36 parts of nano calcium carbonate are mixed, vacuum dehydration is performed at 100-120°C for 2h, then the temperature is lowered to 70-80°C, 124 parts by mass of IPDI is added, pre-polymerization is performed for 3h, then the temperature is lowered to 50-60°C, 1.5 parts by mass of dibutyltin dilaurate catalyst is added, stirring is continued for 1h until the viscosity is stable, then the reaction mixture is cooled to room temperature, sealed and packaged under nitrogen, to obtain a silicone-modified polyurethane waterproof coating.

[0034] The physical and mechanical properties of the polyurethane waterproof coatings obtained in examples 1-3 and comparative examples 1-2 above are tested, the test standard is GB / T 19250-2013, and the test results are shown in Table 1 below.

[0035] Table 1: Mechanical properties and water absorption test results of the polyurethane waterproof coatings of examples 1-3 and comparative examples 1-2 As can be seen from the comparison results of comparative example 1 and examples 1-3 in Table 1, without using silicone-modified hydroxyl-terminated polybutadiene for copolymerization modification, the elongation at break of the obtained polyurethane waterproof coating is significantly reduced, the water absorption is significantly increased, the low-temperature bending property after heat treatment and artificial climate aging is significantly reduced, and the tensile strength retention rate and elongation at break are significantly reduced. It shows that the use of silicone-modified hydroxyl-terminated polybutadiene for copolymerization modification can significantly improve the flexibility, water resistance, heat resistance and weather resistance of the polyurethane waterproof coating, and can maintain high strength. As can be seen from the comparison results of comparative example 2 and comparative example 1 and examples 1-3, simply using hydroxyl-terminated polybutadiene for copolymerization modification, the elongation at break of the obtained polyurethane waterproof coating is significantly increased, but the tensile strength is significantly reduced; the water absorption is significantly reduced compared with the unmodified polyurethane waterproof coating in comparative example 1, but is significantly increased compared with examples 1-3; in addition, the heat treatment performance and artificial climate aging treatment performance of comparative example 2 are significantly reduced compared with comparative example 1 and examples 1-3. The above results show that simply using hydroxyl-terminated polybutadiene for copolymerization modification can significantly improve the flexibility and water resistance of the polyurethane waterproof coating, but will lead to a decrease in strength, heat resistance and weather resistance, and the use of end-hydrogen silicone oil to crosslink the hydroxyl-terminated polybutadiene in the present application can avoid the above defects. The reason is that the crosslinked polysiloxane chain can slow down the breakage of double bonds in polybutadiene and material degradation under light, high temperature or oxidation, and plays a role in enhancing the stability of the polymer structure. The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A method for preparing a silicone-modified polyurethane waterproof coating, characterized in that: The method comprises the following preparation steps: (1) Preparation of silicone-modified hydroxy-terminated polybutadiene: Adding hydroxyl-terminated polybutadiene and hydrogen-terminated silicone oil in a molar ratio of 1.8-2.2:1 into an organic solvent and mixing and dissolving them uniformly, then adding a vinyl platinum catalyst and heating and stirring to react to obtain an organosilicon-modified hydroxyl-terminated polybutadiene solution; (2) Preparation of silicone-modified polyurethane waterproof coating: Add polyol and filler to the organosilicon-modified hydroxy-terminated polybutadiene solution of step (1), mix and dehydrate at 100-120°C in vacuum, then cool to 70-80°C, add polyisocyanate and carry out prepolymerization for 2-4 hours, then cool to 50-60°C, add catalyst and continue stirring and reacting for 0.5-1 hour, cool to room temperature, fill the reaction mixture with nitrogen and seal it to obtain an organosilicon-modified polyurethane waterproof coating.

2. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 1, characterized in that: The hydroxyl value of the hydroxy-terminated polybutadiene in step (1) is 0.5-2 mmol / g, and the average molecular weight is 1000-4000; the hydrogen content of the hydrogen-terminated silicone oil is 0.05-0.2 wt%, and the average molecular weight is 1000-4000.

3. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 1, characterized in that: The organic solvent in step (1) is any one of toluene, xylene, acetone, ethyl acetate, butyl acetate, and tetrahydrofuran, or a mixed solvent of at least two thereof; the amount of the organic solvent is such that the solid content of the resulting organosilicon-modified polyurethane waterproof coating is ≥85%.

4. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 1, characterized in that: The temperature of the heating and stirring reaction in step (1) is 70-90° C. and the time is 3-8 hours; the solid content of the organosilicon-modified hydroxy-terminated polybutadiene solution is 30%-60%.

5. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 1, characterized in that: The polyol in step (2) is a mixture of a macromolecular diol with an average molecular weight of 500-2000 and a small molecule diol in a molar ratio of 1:1-2; the macromolecular diol is at least one of polycarbonate diol, polyester diol, and polyether diol, and the small molecule diol is at least one of ethylene glycol, propylene glycol, and butanediol.

6. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 1, characterized in that: The mass of the polyol added in step (2) is 3-10 times the solid content of the organosilicon-modified hydroxy-terminated polybutadiene solution.

7. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 6, characterized in that: The filler in step (2) is calcium carbonate, and the amount of the filler added is 5%-30% of the mass of the polyol.

8. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 6, characterized in that: The polyisocyanate in step (2) is toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate or dicyclohexylmethane diisocyanate, and the amount of the polyisocyanate added is 1.2-1.5 times the molar amount of the polyol.

9. The method for preparing a silicone-modified polyurethane waterproof coating according to claim 6, characterized in that: The catalyst in step (2) is dibutyltin dilaurate, and the amount of catalyst added is 0.5%-1% of the mass of the polyol.

10. A silicone-modified polyurethane waterproof coating, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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