A modified alkoxy crosslinker, dealcoholized silicone sealant and preparation method thereof

Abstract

The application provides a modified alkoxy crosslinking agent, a dealcoholized silicone sealant and a preparation method thereof, and relates to the technical field of sealants. The modified alkoxy crosslinking agent is a trimethoxysilane-terminated polyurethane oligomer, and high-activity groups are introduced to accelerate the curing speed of the silicone sealant. The preparation method of the dealcoholized silicone sealant is that the modified alkoxy crosslinking agent, alpha, omega-dihydroxypolydimethylsiloxane, inorganic fillers, a complex coupling agent and a catalyst are used to prepare a silicone weather-resistant sealant in an alcohol type system. The silicone weather-resistant sealant has excellent weather resistance and mechanical properties, high displacement capacity, fast surface drying speed, and the alcohol small molecules removed during vulcanization are environmentally friendly and have no corrosiveness to most building materials, and the operation is simple and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of sealant technology, and in particular to a modified alkoxy crosslinking agent, a dealcoholized silicone sealant, and a method for preparing the same. Background Technology

[0002] One-component condensation-type room temperature vulcanizing liquid silicone rubber is a paste-like substance made by mixing α,ω-polydimethylsiloxane as a base polymer with crosslinking agents, fillers, plasticizers, coupling agents, and catalysts in a moisture-proof container. It cures at room temperature by reacting with water in the air to form elastic silicone rubber. It has many excellent properties such as a wide operating temperature range, excellent weather resistance, good electrical insulation properties, excellent biocompatibility, and good adhesion to materials. The de-alcoholized silicone sealant has the advantages of being odorless and non-corrosive, and is therefore widely used in construction, electronics, and automotive industries.

[0003] Currently, the mainstream single-component de-alcoholized silicone sealants on the market are generally formulated with α,ω-dihydroxypolydimethylsiloxane as the main resin, methyltrimethoxysilane as the crosslinking agent, and titanium or tin compounds as catalysts. However, due to the low activity of the crosslinking agent, the overall curing speed is slow, which restricts the application scenarios of de-alcoholized silicone sealants.

[0004] Existing patent CN112662370B discloses a one-component de-alcoholized silicone sealant and its preparation method. This method uses a composition of 1,2-bis(trimethoxysilyl ethane) and propyltrimethoxysilane as a composite crosslinking agent, and prepares a one-component de-alcoholized silicone sealant with α,ω-dihydroxypolydimethylsiloxane, plasticizer, inorganic filler, silane coupling agent and catalyst in a specific weight ratio. The internal curing speed of the prepared sealant is relatively fast and the physical and mechanical properties are good. However, the activity of 1,2-bis(trimethoxysilyl ethane) is not high and the crosslinking points are too dense, which is not conducive to the mechanical properties of the silicone sealant. In addition, the existing technology for preparing silane-modified polyurethane sealant using silane-terminated polyurethane has the following defects: (1) The viscosity increases significantly after adding the end-capping agent, and the curing speed of the prepared polyurethane silane-modified polyurethane sealant is slow. For example, patent CN101348550A discloses a method for synthesizing silane-terminated polyurethane prepolymers. This method involves reacting hydroxyl-terminated polyethers or polyesters with diisocyanates under the catalysis of bismuth, zinc, etc., to synthesize isocyanate-terminated polyurethane prepolymers. Then, the synthesized isocyanate-terminated polyurethane prepolymers are reacted with functional silanes to obtain silane-terminated polyurethane prepolymers. Although this method can obtain silane-terminated prepolymers, the hydrolytic reactivity of the silane-terminated prepolymers prepared by this method is very low, the viscosity increases significantly, and the curing speed of silane-modified polyurethane sealants prepared by this method is also very slow. (2) The silanes used to prepare silane-terminated polyurethane prepolymers all have the disadvantage of being difficult to end-cap. For example, patent CN101402845A discloses a method for preparing flame-retardant building sealant. The method first uses polyol and isocyanate to react under the condition of dibutyltin dilaurate catalyst to obtain polyurethane prepolymer, then adds end-capping silane coupling agent to obtain silane-endopeptide polyurethane prepolymer, and finally adds various additives and fillers to produce sealant. However, the end-capping silanes used in this method all have the disadvantage of difficulty in end-capping. In addition, this method also has the disadvantage of excessive viscosity change.

[0005] Therefore, this invention designs a modified alkoxy crosslinking agent with rapid deep curing and good mechanical properties, a dealcoholized silicone sealant, and a method for preparing the same. Summary of the Invention

[0006] This invention provides a modified alkoxy crosslinking agent, a dealcoholized silicone sealant, and a method for preparing the same, with the aim of solving the following problems.

[0007] To achieve the above objectives, embodiments of the present invention provide a modified alkoxy crosslinking agent, a de-alcoholized silicone sealant, and a method for preparing the same. The modified alkoxy crosslinking agent is a trimethoxysilane-terminated polyurethane oligomer, which accelerates the curing speed of the silicone sealant by incorporating highly active groups. The method for preparing the de-alcoholized silicone sealant involves reacting the modified alkoxy crosslinking agent with α,ω-dihydroxy polysiloxane, inorganic fillers, a complex crosslinking agent, and a catalyst in an alcohol-based system to obtain a weather-resistant silicone sealant. This weather-resistant silicone sealant possesses excellent weather resistance and mechanical properties, high displacement capability, and fast surface drying speed. The small alcohol molecules removed during vulcanization are environmentally friendly, non-corrosive to most building materials, and easy to operate, making it suitable for large-scale production.

[0008] One aspect of the present invention provides a modified alkoxy crosslinking agent, wherein the modified alkoxy crosslinking agent has the following structural formula:

[0009]

[0010] in, 3≤n≤10.

[0011] Based on a general inventive concept, the present invention also provides a method for preparing the above-mentioned modified alkoxy crosslinking agent, comprising the following steps:

[0012] The product is prepared by reacting 3-isocyanate-propyltrimethoxysilane, polybutylene adipate diol, and a catalyst under nitrogen or inert gas protection.

[0013] Preferably, the molar ratio of 3-isocyanate-propyltrimethoxysilane to polyethylene glycol is 2.2:1.

[0014] Preferably, the degree of polymerization n in the polybutylene adipate diol is 3 to 10.

[0015] Preferably, the reaction temperature is 70°C and the reaction time is 6 hours.

[0016] Preferably, the catalyst is dibutyltin dilaurate, used in an amount of 0.05 wt.%.

[0017] Another aspect of the present invention provides a dealcoholized silicone sealant, wherein the modified crosslinking agent is the modified alkoxy crosslinking agent described above or the modified alkoxy crosslinking agent prepared by the above preparation method.

[0018] Preferably, the product comprises the following components by mass:

[0019]

[0020] Preferably, the viscosity of the α,ω-dihydroxypolysiloxane at 25°C is 5–150 Pa·s; the viscosity of the dimethyl silicone oil at 25°C is 0.1–10 Pa·s; the crosslinking agent I is at least one of methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, and propyltriethoxysilane; the complex crosslinking agent is at least two of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, γ-glycidyl etheroxypropyltriethoxysilane, N-β-aminoethylγ-aminopropyltriethoxysilane, glycidyltriethoxysilane, and glycidyltrimethoxysilane; and the titanate vulcanizing agent is diisopropoxytitanium bis(ethyl acetoacetate) chelate.

[0021] Another aspect of the present invention provides a method for preparing the above-mentioned dealcoholized silicone sealant, comprising the following steps:

[0022] S1: Add α,ω-dihydroxypolysiloxane, dimethyl silicone oil, and nano-activated calcium carbonate to a kneader and dehydrate and blend for 30 to 300 minutes at a temperature of 80 to 150°C and a vacuum of -0.06 to 0.099 MPa to obtain the base material;

[0023] S2: At room temperature, the base material, crosslinking agent I and modified crosslinking agent obtained above are added to a planetary mixer or a high-speed dispersion mixer, and reacted for 5 to 30 minutes under vacuum of -0.02 to 0.04 MPa and rotation speed of 10 to 800 rpm; then, the complex crosslinking agent and titanate vulcanizing agent are added, and reacted for 30 to 120 minutes under vacuum of -0.06 to 0.099 MPa and rotation speed of 10 to 800 rpm to obtain the product.

[0024] Reaction mechanism

[0025] This invention addresses the shortcomings of existing dealcohol-type silicone sealants, such as low crosslinking activity and slow overall curing speed. First, a trimethoxy-terminated modified alkoxy crosslinking agent was prepared and then introduced into the dealcohol-type silicone sealant, ultimately resulting in a dealcohol-type silicone sealant with fast curing speed and excellent mechanical properties. Because the urethane group has an electron-donating effect, it can significantly improve the hydrolytic activity of the methoxy group and accelerate the reaction rate. Furthermore, ester groups with good hydrophilic properties are introduced into the polysiloxane molecular backbone through chemical bonds, increasing the affinity for moisture in the air and accelerating the penetration of moisture into the sealant. Simultaneously, the introduction of polar groups such as ester groups and urethane groups can also greatly improve the adhesion and mechanical properties of the dealcohol-type silicone sealant to polar substrates.

[0026] The above-described solution of the present invention has the following beneficial effects:

[0027] 1. The present invention prepares a modified crosslinking agent by reacting 3-isocyanate-propyltrimethoxysilane, polybutylene adipate diol and a catalyst, thereby accelerating the curing speed of de-alcoholized silicone sealant.

[0028] 2. The de-alcoholized silicone sealant of the present invention is environmentally friendly. The small molecules released during the curing process are alcohol molecules. It adopts a neutral curing system and is non-corrosive to building materials such as metals, glass, and concrete. It has a wide range of applications.

[0029] 3. The de-alcoholized silicone sealant of the present invention has good adhesion and water-resistant adhesion. After curing, it forms a strong bond with most building materials without the need for a primer.

[0030] 4. The de-alcoholized silicone sealant product of the present invention is easy to apply. Detailed Implementation

[0031] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.

[0032] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0033] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0034] This invention addresses existing problems by providing a modified alkoxy crosslinking agent, a dealcoholized silicone sealant, and a method for preparing the same.

[0035] Example 1

[0036] A method for preparing a dealcoholized silicone sealant includes the following steps:

[0037] First, 100 parts of α,ω-dihydroxypolydimethylsiloxane (viscosity 50000 mPa·s), 110 parts of nano-activated calcium carbonate, and 5 parts of dimethyl silicone oil (viscosity 500 mPa·s) were added to a kneader and dehydrated and mixed for 120 min at 120℃ and -0.09 MPa vacuum to obtain a base material, which was then cooled for later use. Next, the above base material was added to a planetary mixer, followed by 5 parts of methyltrimethoxysilane and modified alkoxy... Two parts of crosslinking agent were chemically reacted with the base material under a vacuum of 0.04 MPa and a rotation speed of 300 rpm for 15 minutes. Finally, two parts of γ-aminopropyltrimethoxysilane, 0.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane, and four parts of diisopropoxytitanium bis(ethyl acetoacetate) chelate were chemically reacted under a vacuum of -0.09 MPa and a rotation speed of 300 rpm for 40 minutes to prepare a long-term stable alcohol-based silicone sealant.

[0038] Example 2

[0039] A method for preparing a dealcoholized silicone sealant includes the following steps:

[0040] First, 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 60000 mPa·s, 120 parts of nano-activated calcium carbonate, and 7 parts of dimethyl silicone oil with a viscosity of 500 mPa·s were added to a kneader and dehydrated and mixed for 150 min at a temperature of 130℃ and a vacuum of -0.09 MPa to obtain a base material, which was then cooled for later use. Next, the above base material was added to a planetary mixer, followed by 4.5 parts of methyltrimethoxysilane and modified alkoxy crosslinking agents. 2.5 parts of the agent, together with the base material, were chemically reacted for 15 minutes under a vacuum of -0.03 MPa and a rotation speed of 350 rpm. Finally, 1.5 parts of γ-aminopropyltrimethoxysilane, 1 part of γ-glycidyl etheroxypropyltrimethoxysilane, and 4.5 parts of diisopropoxytitanium bis(ethyl acetoacetate) chelate were chemically reacted for 40 minutes under a vacuum of -0.09 MPa and a rotation speed of 300 rpm to prepare a long-term stable alcohol-based silicone sealant.

[0041] Example 3

[0042] A method for preparing a dealcoholized silicone sealant includes the following steps:

[0043] First, 100 parts of α,ω-dihydroxypolydimethylsiloxane (viscosity 80000 mPa·s), 100 parts of nano-activated calcium carbonate, and 10 parts of dimethyl silicone oil (viscosity 500 mPa·s) were added to a kneader and dehydrated and mixed for 180 minutes at 120°C and -0.09 MPa vacuum to obtain a base material, which was then cooled for later use. Next, the above base material was added to a planetary mixer, followed by 4.5 parts of methyltrimethoxysilane and modified alkoxy... Three parts of crosslinking agent were chemically reacted with the base material under vacuum of -0.03 MPa and rotation speed of 300 rpm for 15 minutes. Finally, one part of γ-aminopropyltrimethoxysilane, 1.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane, and five parts of diisopropoxytitanium bis(ethyl acetoacetate) chelate were chemically reacted under vacuum of -0.09 MPa and rotation speed of 300 rpm for 40 minutes to prepare a long-term stable alcohol-based silicone sealant.

[0044] Example 4

[0045] A method for preparing a dealcoholized silicone sealant includes the following steps:

[0046] First, 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s, 120 parts of nano-activated calcium carbonate, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s were added to a kneader and dehydrated and mixed for 120 min at 120℃ and a vacuum of -0.09 MPa to obtain a base material, which was then cooled for later use. Next, the above base material was added to a planetary mixer, followed by 4.5 parts of methyltrimethoxysilane and modified alkoxy crosslinking. 3.5 parts of the binder were chemically reacted with the base material under a vacuum of -0.04 MPa and a rotation speed of 300 rpm for 15 minutes. Finally, 1.5 parts of γ-aminopropyltrimethoxysilane, 1 part of γ-glycidyl etheroxypropyltrimethoxysilane, and 4 parts of diisopropoxytitanium bis(ethyl acetoacetate) chelate were chemically reacted under a vacuum of -0.09 MPa and a rotation speed of 300 rpm for 40 minutes to prepare a long-term stable alcohol-based silicone sealant.

[0047] Comparative Example 1

[0048] The difference between this comparative example and Example 1 is that no modified crosslinking agent was added.

[0049] First, 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of nano-activated calcium carbonate, and 8 parts of dimethyl silicone oil with a viscosity of 500 mPa·s were added to a kneader and dehydrated and mixed for 140 min at a temperature of 130℃ and a vacuum of -0.09 MPa to obtain a base material, which was then cooled for later use. Next, the above base material was added to a planetary mixer, and then 7 parts of methyltrimethoxysilane were added. The mixture was then chemically reacted with the base material at a vacuum of -0.03 MPa and a rotation speed of 300 rpm for 15 minutes. Finally, 2 parts of γ-aminopropyltrimethoxysilane, 1 part of γ-glycidyl etheroxypropyltrimethoxysilane, and 4.5 parts of diisopropoxytitanium bis(ethyl acetoacetate) chelate were chemically reacted at a vacuum of -0.09 MPa and a rotation speed of 300 rpm for 40 minutes to prepare a long-term stable alcohol-based silicone sealant.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is the addition of an excessive amount of modified crosslinking agent.

[0052] First, 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 80000 mPa·s, 90 parts of nano-activated calcium carbonate, and 10 parts of dimethyl silicone oil with a viscosity of 500 mPa·s were added to a kneader and dehydrated and mixed for 160 min at 120℃ and a vacuum of -0.09 MPa to obtain a base material, which was then cooled for later use. Next, the above base material was added to a planetary mixer, followed by 4.5 parts of methyltrimethoxysilane and modified alkoxy crosslinking. Six parts of the binder were chemically reacted with the base material under a vacuum of -0.03 MPa and a rotation speed of 300 rpm for 15 minutes. Finally, 1.5 parts of γ-aminopropyltrimethoxysilane, 0.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane, and 5 parts of diisopropoxytitanium bis(ethyl acetoacetate) chelate were chemically reacted under a vacuum of -0.09 MPa and a rotation speed of 300 rpm for 40 minutes to prepare a long-term stable alcohol-based silicone sealant.

[0053] The surface drying time of the de-alcoholized one-component silicone sealant in the above examples and comparative examples was tested according to "GB / T 13477 Test Methods for Building Sealing Materials". The internal curing speed of the sealant was tested according to Method 2: the wedge groove method specified in "GB / T 32369-2015 Determination of Curing Degree of Sealants". The tensile strength and elongation at break were tested according to the requirements of Type 1 specimens in 6.1 of GB / T 528-2009. Detailed test results are shown in Table 1.

[0054] Table 1. Overall performance test results of each embodiment and comparative example.

[0055]

[0056]

[0057] By comparing Examples 1, 2, 3, and 4 with Comparative Examples 1 and 2, it can be seen that the de-alcoholized silicone sealant prepared by the modified crosslinking agent introduced in this invention can effectively accelerate the surface drying time, improve the curing depth, and at the same time increase the tensile strength of the silicone sealant.

[0058] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dealcoholized silicone sealant, characterized in that, According to the mass meter, it includes the following components: 100 parts of α,ω-dihydroxypolysiloxane 1-10 parts of dimethyl silicone oil 70-140 parts of nano-activated calcium carbonate Crosslinking agent I 3~10 parts Modified crosslinking agent 0.5~3 parts 1-3 doses of combined couple agent 2-6 parts of titanate vulcanizing agent; The structural formula of the modified crosslinking agent is as follows: 3≤n≤10, the modified crosslinking agent is prepared by reacting 3-isocyanate-propyltrimethoxysilane, polybutylene adipate diol and catalyst under nitrogen or inert gas protection; The reaction temperature is 70℃ and the reaction time is 6 h; the catalyst is dibutyltin dilaurate, and the amount used is 0.05 wt.%; the molar ratio of 3-isocyanate-propyltrimethoxysilane and polybutylene adipate diol is 2.2:

1.

2. The dealcoholized silicone sealant according to claim 1, characterized in that, The viscosity of the α,ω-dihydroxypolysiloxane at 25°C is 5–150 Pa·s.

3. The dealcoholized silicone sealant according to claim 1, characterized in that, The viscosity of the dimethyl silicone oil at 25°C is 0.1–10 Pa·s.

4. The dealcoholized silicone sealant according to claim 1, characterized in that, The crosslinking agent I is at least one of methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, and propyltriethoxysilane.

5. The dealcoholized silicone sealant according to claim 1, characterized in that, The complex coupling agent is at least two of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, γ-glycidyl etheroxypropyltriethoxysilane, N-β-aminoethylγ-aminopropyltriethoxysilane, glycidyltriethoxysilane, and glycidyltrimethoxysilane.

6. The dealcoholized silicone sealant according to claim 1, characterized in that, The titanate ester sulfiding agent is a diisopropoxytitanium bis(ethyl acetoacetate) chelate.

7. The method for preparing the dealcoholized silicone sealant according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Add α,ω-dihydroxypolysiloxane, dimethyl silicone oil, and nano-activated calcium carbonate to a kneader and dehydrate and blend for 30 to 300 minutes at a temperature of 80 to 150°C and a vacuum of -0.06 to 0.099 MPa to obtain the base material; S2: At room temperature, the base material, crosslinking agent I and modified crosslinking agent obtained above are added to a planetary mixer or a high-speed dispersion mixer, and reacted for 5 to 30 minutes under vacuum of -0.02 to 0.04 MPa and rotation speed of 10 to 800 rpm; then, the complex crosslinking agent and titanate vulcanizing agent are added, and reacted for 30 to 120 minutes under vacuum of -0.06 to 0.099 MPa and rotation speed of 10 to 800 rpm to obtain the product.

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