A modified silane coupling agent, a preparation method thereof and application thereof in water-based paint
By introducing hydrophobic groups and an "oil-in-water" structure into silane coupling agents, the problem of easy hydrolysis of silane coupling agents in water-based coatings is solved, achieving stable storage and excellent interfacial bonding effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NINGBO INST OF MATERIALS TECH & ENG CHINESE ACAD OF SCI
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-23
AI Technical Summary
Existing silane coupling agents are prone to hydrolysis and failure in water-based coatings, resulting in cumbersome operation, unstable performance, and inefficient use of the "add as needed" method, which also makes long-term storage impossible.
Hydrophobic groups are introduced into the molecular structure of silane coupling agents to form hydrophobic siloxanes. Through the design of an "oil-in-water" structure, they can be made to exhibit a stable dispersion state in water-based coatings, thus hindering hydrolysis reactions.
It significantly improves the storage stability and interfacial bonding performance of silane coupling agents in water-based coatings, simplifies the operation process, and enhances coating adhesion and salt spray resistance.
Smart Images
Figure CN122255481A_ABST
Abstract
Description
Technical Field
[0001] This invention pertains to silane coupling agent modification technology, specifically relating to a modified silane coupling agent, its preparation method, and its application in water-based coatings. Background Technology
[0002] Silane coupling agents are a class of organosilicon compounds with a bifunctional structure, typically with the formula RSiX3, where R represents a functional group reactive with organic polymers (such as amino, epoxy, methacryloxy, etc.), and X represents a hydrolyzable group (such as methoxy, ethoxy, halogen, etc.). These compounds can bridge the gap between inorganic substrates (such as metals, glass, ceramics, etc.) and organic polymers (such as coating resins), significantly improving interfacial adhesion and thus enhancing key properties of coatings such as adhesion, salt spray resistance, and water resistance. They are widely used in water-based coatings, adhesives, and composite materials.
[0003] However, the methoxy (-OCH3) or ethoxy (-OC2H5) groups in silane coupling agents have strong hydrophilicity and are prone to hydrolysis with water molecules in water-based coating systems to generate unstable silanols (-Si-OH). The silanols further undergo self-condensation reactions to form siloxanes or polymers (Si-O-Si), causing the silane coupling agent to lose its interfacial coupling activity.
[0004] To prevent premature hydrolysis and inactivation of silane coupling agents in water-based coatings, the industry generally adopts a "use-as-you-go" approach. This involves accurately weighing the silane coupling agent and adding it to the coating system before application, then quickly stirring until homogeneous and using immediately. However, this method has significant drawbacks: firstly, precise weighing is required for each use, which is cumbersome, inefficient, and prone to causing fluctuations in coating performance due to weighing errors; secondly, uneven stirring can result in localized concentrations of the silane coupling agent that are too high or too low. Excessive concentration can lead to coating gelation and loss of gloss, while insufficient concentration will fail to achieve the desired interface modification effect, causing significant inconvenience to actual production and application.
[0005] In existing technologies, patent CN201911318157.8 replaces some of the methoxy groups in KH560 with isopropoxy groups, retaining its hydrolysis characteristics while increasing its hydrolysis threshold. However, isopropoxy groups have low steric hindrance, making it difficult to achieve long-term stable storage in acrylic systems (pH>7). Furthermore, the epoxy groups in KH560 are at risk of self-polymerization under the influence of dimethylethanolamine. Patent 202210453946.8 provides a two-component waterborne resin system cured with an epoxy-containing silane coupling agent and its preparation method. This system combines and regulates the excellent properties of organosilicon and thermosetting resins in an waterborne system, resulting in a paint film with high hardness, good flexibility, high transparency, high fullness, and high gloss. However, it still requires "adding it only when needed." Additionally, controlling the pH value of waterborne coatings or adding hydrolysis inhibitors can only temporarily delay hydrolysis and cannot fundamentally solve the problem of long-term storage of silane coupling agents in waterborne coating systems. Therefore, developing a modified silane coupling agent that can be stored in waterborne coating systems for a long time, is not easily hydrolyzed, and can effectively retain the interface enhancement effect has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0006] The main objective of this invention is to provide a modified silane coupling agent, its preparation method, and its application in water-based coatings, so as to overcome the shortcomings of the prior art.
[0007] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:
[0008] This invention provides a method for preparing a modified silane coupling agent, comprising:
[0009] A first reaction system comprising at least a silane coupling agent and a chain extender is subjected to a first reaction to obtain a hydrophobic siloxane; wherein the chain extender comprises any one or more combinations of n-butanol, sec-butanol, pentanol, neopentyl glycol, trimethylpentyl glycol, hexanediol, n-hexanol, n-octanol, octanediol, dodecanol, hexadecyl alcohol, octadecanol, perfluoro-1-hexanol, perfluoro-1-octanol, p-fluorobenzyl alcohol, trifluoromethylbenzyl alcohol, hydrogenated bisphenol A, 1,4-cyclohexanediol, and cyclohexylethanol.
[0010] And, a first reaction is carried out on a second reaction system containing at least the hydrophobic siloxane and a hydrophilic substance to obtain a modified silane coupling agent; wherein the hydrophilic substance includes methoxy polyethylene glycol and / or polyetheramine.
[0011] The present invention also provides a modified silane coupling agent prepared by the aforementioned preparation method.
[0012] The present invention also provides the application of the aforementioned modified silane coupling agent in waterborne epoxy emulsion coatings.
[0013] This invention also provides an aqueous epoxy emulsion coating comprising: the aforementioned modified silane coupling agent, wherein the modified silane coupling agent is dispersed in the aqueous epoxy emulsion coating as an oil phase in a "water-in-oil" structure.
[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0015] (1) This invention introduces specific hydrophobic groups into the molecular structure of silane coupling agents, and utilizes the steric hindrance effect and hydrophobic effect of the hydrophobic groups to effectively isolate water molecules from the contact between water molecules and the methoxy and ethoxy groups in the silane coupling agent molecules, thereby significantly slowing down its hydrolysis rate.
[0016] (2) Through the “water-in-oil” structural design, the hydrophobic active component is preferentially encapsulated in the oil phase core to form dispersed oil droplet particles; the continuous phase is an aqueous medium, and a dense interface film is formed between the oil droplets and the aqueous phase. This interface film forms a stable molecular barrier, which can effectively prevent water molecules in the continuous phase from penetrating into the oil phase core, thereby further improving the storage stability of silane coupling agent in waterborne epoxy coatings. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is the infrared spectrum of the modified silane coupling agent prepared in Example 1 of this invention. Detailed Implementation
[0019] In view of the deficiencies of existing technologies, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. Its main function is to introduce hydrophobic groups into the molecular structure of the silane coupling agent, utilizing the steric hindrance effect of these groups to slow down the hydrolysis rate of methoxy or ethoxy groups. Furthermore, by introducing polyether segments into the molecular structure of the silane coupling agent, the silane coupling agent exhibits an "oil-in-water" spatial structure in water. This achieves long-term stable storage in water-based coatings while retaining the interfacial bonding function of the silane coupling agent, solving the operational problem of "adding only what is needed" in existing technologies.
[0020] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] Specifically, as one aspect of the technical solution of this invention, the preparation method of a modified silane coupling agent includes:
[0022] A first reaction system comprising at least a silane coupling agent and a chain extender is subjected to a first reaction to obtain a hydrophobic siloxane; wherein the chain extender comprises any one or more combinations of n-butanol, sec-butanol, pentanol, neopentyl glycol, trimethylpentyl glycol, hexanediol, n-hexanol, n-octanol, octanediol, dodecanol, hexadecyl alcohol, octadecanol, perfluoro-1-hexanol, perfluoro-1-octanol, p-fluorobenzyl alcohol, trifluoromethylbenzyl alcohol, hydrogenated bisphenol A, 1,4-cyclohexanediol, and cyclohexylethanol, and is not limited thereto;
[0023] And, a first reaction is carried out on a second reaction system containing at least the hydrophobic siloxane and a hydrophilic substance to obtain a modified silane coupling agent; wherein the hydrophilic substance includes methoxy polyethylene glycol and / or polyetheramine.
[0024] In some preferred embodiments, the temperature of the first reaction is 60°C to 200°C.
[0025] Furthermore, the temperature of the first reaction is 120℃~190℃.
[0026] In some preferred embodiments, the first reaction takes 0.5 to 5 hours.
[0027] In some preferred embodiments, the temperature of the second reaction is 60°C to 180°C.
[0028] Furthermore, the temperature of the second reaction is 90℃~120℃.
[0029] In some preferred embodiments, the second reaction takes 1 to 5 hours.
[0030] In some preferred embodiments, the chain extender includes any one or more combinations of p-fluorobenzyl alcohol, trifluoromethylbenzyl alcohol, hydrogenated bisphenol A, 1,4-cyclohexanediethanol, and cyclohexylethanol, but is not limited thereto.
[0031] In some preferred embodiments, the silane coupling agent comprises any one or more combinations of γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-glycidyletheroxypropyltrimethoxysilane, γ-glycidyletheroxypropylmethyldimethoxysilane, γ-glycidyletheroxypropyltriethoxysilane, γ-glycidyletheroxypropylmethyldiethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane, and is not limited thereto.
[0032] In some preferred embodiments, the molecular weight of the methoxy polyethylene glycol is any one of 350, 550, 750, 1000, 2000, 5000, 10000, and 20000, but is not limited thereto.
[0033] In some preferred embodiments, the mass ratio of the silane coupling agent to the chain extender is 100:20~300.
[0034] In some preferred embodiments, the mass ratio of the hydrophobic silane coupling agent to the hydrophilic substance is 100:5~15.
[0035] Another aspect of the present invention provides a modified silane coupling agent prepared by the aforementioned preparation method.
[0036] Another aspect of the present invention provides the application of the aforementioned modified silane coupling agent in waterborne epoxy emulsion coatings.
[0037] Another aspect of the present invention provides an aqueous epoxy emulsion coating comprising: the aforementioned modified silane coupling agent, wherein the modified silane coupling agent is dispersed in the aqueous epoxy emulsion coating as an oil phase in a "water-in-oil" structure.
[0038] In some preferred embodiments, the modified silane coupling agent in the waterborne epoxy emulsion coating is 0.3~1.5 wt%. It is added directly to the waterborne epoxy coating system, stirred evenly, and then stored or applied.
[0039] Furthermore, the content of the modified silane coupling agent in the waterborne epoxy emulsion coating is 0.5~1.0 wt%. When the addition amount is too low, the interface modification effect cannot be fully utilized, and the improvement of coating adhesion and salt spray resistance is not obvious; when the addition amount is too high, it is easy to cause problems such as slow drying speed and low gloss of the coating system.
[0040] The modified silane coupling agent of this invention can be directly added to waterborne epoxy emulsion coatings without needing to be added on the spot. It can significantly improve the film adhesion and salt spray resistance of waterborne coatings without affecting the storage stability and application performance of the coatings.
[0041] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.
[0042] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.
[0043] Example 1
[0044] In a reactor equipped with a stirrer and temperature control device, 50 parts of γ-aminopropyltriethoxysilane and 50 parts of γ-glycidyl etheroxypropyltriethoxysilane, along with 10 parts of trimethylpentanediol and 10 parts of perfluoro-1-octanol, were added in a set molar ratio. The stirring was started and the temperature was slowly increased to 120°C and maintained at this temperature for 0.5 h to allow the silane monomers and chain extenders to undergo a chain extension reaction, yielding a long-chain hydrophobic modified siloxane intermediate. The reaction system was then cooled to 60°C, and 9 parts of methyloxy polyethylene glycol (molecular weight 500) and 9 parts of methoxy polyethylene glycol (molecular weight 2000) hydrophilic monomers were added to the reactor. The temperature was then increased to 90°C and maintained at this temperature for 1 h to achieve bonding and structural regulation between the hydrophilic groups and the hydrophobic siloxane backbone. After the reaction, the mixture was cooled to room temperature to obtain a modified silane coupling agent possessing both a hydrophobic framework and hydrophilic functional groups. The infrared spectrum of the modified silane coupling agent prepared in this example is shown below. Figure 1 As shown by the red line in the image, Figure 1 The blue line in the figure represents another batch of modified silane coupling agent prepared using the same method as in Example 1. As can be seen from the figure, the modified silane coupling agents prepared in different batches are the same.
[0045] Example 2
[0046] In a reactor equipped with a stirrer and temperature control device, 100 parts of γ-aminopropyltrimethoxysilane, 150 parts of n-butanol, and 150 parts of sec-butanol were added in a set molar ratio. The stirring was started and the temperature was slowly raised to 190°C and maintained at this temperature for 5 hours to allow the silane monomer and chain extender to undergo a chain extension reaction, thus preparing a long-chain hydrophobic modified siloxane intermediate. The reaction system was then cooled to 120°C, and 10 parts of methoxy polyethylene glycol with a molecular weight of 350 and 10 parts of methoxy polyethylene glycol hydrophilic monomer with a molecular weight of 3000 were added to the reactor. The temperature was then raised to 180°C and maintained at this temperature for another 5 hours to achieve the bonding and structural regulation of the hydrophilic groups and the hydrophobic siloxane backbone. After the reaction was completed, the mixture was cooled to room temperature to obtain a modified silane coupling agent with both a hydrophobic framework and hydrophilic functional groups.
[0047] Example 3
[0048] In a reactor equipped with a stirrer and temperature control device, 100 parts of γ-glycidoxypropyltrimethoxysilane and 50 parts of neopentyl glycol were added at a set molar ratio. The stirring was started and the temperature was slowly raised to 160°C and maintained at this temperature for 2 hours to allow the silane monomer and chain extender to undergo a chain extension reaction, thus obtaining a long-chain hydrophobic modified siloxane intermediate. The reaction system was then cooled to 90°C, and 15 parts of polyetheramine were added to the reactor. The temperature was then raised to 120°C and maintained at this temperature for another 5 hours to achieve the bonding and structural regulation of the hydrophilic groups and the hydrophobic siloxane backbone. After the reaction was completed, the mixture was cooled to room temperature to obtain a modified silane coupling agent with both a hydrophobic framework and hydrophilic functional groups.
[0049] Example 4
[0050] In a reactor equipped with a stirrer and temperature control device, 100 parts of γ-methacryloxypropyltrimethoxysilane and 100 parts of trifluoromethylbenzyl alcohol were added at a set molar ratio. The stirring was started and the temperature was slowly raised to 180°C and maintained at this temperature for 4 hours to allow the silane monomer and chain extender to undergo a chain extension reaction, thus obtaining a long-chain hydrophobic modified siloxane intermediate. The reaction system was then cooled to 110°C, and 10 parts of methyl polyethylene glycol with a molecular weight of 1000 and 10 parts of hydrophilic polyethylene oxide monomer with a molecular weight of 1000 were added to the reactor. The temperature was then raised to 120°C and maintained at this temperature for another 4 hours to achieve the bonding and structural regulation of the hydrophilic groups and the hydrophobic siloxane backbone. After the reaction was completed, the mixture was cooled to room temperature to obtain a modified silane coupling agent with both a hydrophobic framework and hydrophilic functional groups.
[0051] Example 5
[0052] In a reactor equipped with a stirrer and temperature control device, 100 parts of γ-glycidoxypropyltriethoxysilane and 100 parts of octadecyl alcohol were added at a set molar ratio. The stirring was started and the temperature was slowly raised to 160°C and held at this temperature for 0.5 h to allow the silane monomer and chain extender to undergo a chain extension reaction, thus preparing a long-chain hydrophobic modified siloxane intermediate. The reaction system was then cooled to 110°C, and 5 parts of methyl polyethylene glycol hydrophilic monomer with a molecular weight of 500 were added to the reactor. The temperature was then raised to 170°C and held at this temperature for another 2 h to achieve bonding and structural regulation between the hydrophilic groups and the hydrophobic siloxane backbone. After the reaction was completed, the mixture was cooled to room temperature to obtain a modified silane coupling agent with both a hydrophobic framework and hydrophilic functional groups.
[0053] Comparative Example 1
[0054] The only difference from Example 1 is that 5 parts of trimethylpentanediol and 5 parts of perfluoro-1-octanol were used in Comparative Example 1.
[0055] Comparative Example 2
[0056] The only difference from Example 1 is that Comparative Example 2 uses 200 parts of trimethylpentanediol and 200 parts of perfluoro-1-octanol.
[0057] Comparative Example 3
[0058] The only difference from Example 1 is that trimethylpentanediol and perfluoro-1-octanol were not used in Comparative Example 3.
[0059] Comparative Example 4
[0060] The only difference from Example 1 is that 18 parts of methoxy polyethylene glycol with a molecular weight of 200 were used in Comparative Example 4.
[0061] Comparative Example 5
[0062] The only difference from Example 1 is that Comparative Example 5 uses 18 parts of methoxy polyethylene glycol with a molecular weight of 25,000.
[0063] Comparative Example 6
[0064] The only difference from Example 1 is that methoxy polyethylene glycol was not used in Comparative Example 6, that is, it was only reacted with a chain extender.
[0065] The modified silane coupling agent obtained in the above examples and comparative examples was used to prepare anti-rust coatings with commercially available waterborne epoxy resin (Huntsman 3961-1). The coating formulations are shown in Table 1.
[0066] Table 1. Formulation of epoxy resin anti-rust coating
[0067] A waterborne epoxy emulsion anti-rust coating, prepared based on a modified silane coupling agent and commercially available epoxy resin, is applied to a carbon steel plate to form a dried anti-rust coating with a thickness of 60~120μm.
[0068] Under the same conditions, the above-mentioned anti-rust coatings and anti-rust coatings were subjected to relevant performance tests. The relevant performance test methods are shown in Table 2.
[0069] Table 2 Test methods for relevant performance of anti-rust coatings
[0070] Table 3. Relevant properties of anti-rust coatings and anti-rust coatings based on the above embodiments and comparative examples of waterborne epoxy emulsions.
[0071] As can be seen from Table 3, the modified silane coupling agent prepared using the embodiments of the present invention has better storage stability and salt spray resistance than the comparative example in the anti-rust coating and coating of waterborne epoxy emulsion. Moreover, the directional coating obtained has excellent construction performance, with good flexibility and good adhesion, and obvious comprehensive performance advantages.
[0072] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.
[0073] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.
Claims
1. A method for preparing a modified silane coupling agent, characterized in that, include: A first reaction system comprising at least a silane coupling agent and a chain extender is subjected to a first reaction to obtain a hydrophobic siloxane; wherein the chain extender comprises any one or more combinations of n-butanol, sec-butanol, pentanol, neopentyl glycol, trimethylpentyl glycol, hexanediol, n-hexanol, n-octanol, octanediol, dodecanol, hexadecyl alcohol, octadecanol, perfluoro-1-hexanol, perfluoro-1-octanol, p-fluorobenzyl alcohol, trifluoromethylbenzyl alcohol, hydrogenated bisphenol A, 1,4-cyclohexanediol, and cyclohexylethanol. And, a first reaction is carried out on a second reaction system containing at least the hydrophobic siloxane and a hydrophilic substance to obtain a modified silane coupling agent; wherein the hydrophilic substance includes methoxy polyethylene glycol and / or polyetheramine.
2. The preparation method according to claim 1, characterized in that: The temperature of the first reaction is 60℃~200℃, preferably 120℃~190℃; and / or the time of the first reaction is 0.5~5h.
3. The preparation method according to claim 1, characterized in that: The temperature of the second reaction is 60℃~180℃, preferably 90℃~120℃; and / or the time of the second reaction is 1~5h.
4. The preparation method according to claim 1, characterized in that: The chain extender includes any one or more combinations of p-fluorobenzyl alcohol, trifluoromethylbenzyl alcohol, hydrogenated bisphenol A, 1,4-cyclohexanediol, and cyclohexyl alcohol. And / or, the silane coupling agent comprises any one or more combinations of γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-glycidyletheroxypropyltrimethoxysilane, γ-glycidyletheroxypropylmethyldimethoxysilane, γ-glycidyletheroxypropyltriethoxysilane, γ-glycidyletheroxypropylmethyldiethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.
5. The preparation method according to claim 1, characterized in that: The molecular weight of the methoxy polyethylene glycol is any one of 350, 550, 750, 1000, 2000, 5000, 10000, and 20000.
6. The preparation method according to claim 1, characterized in that: The mass ratio of the silane coupling agent to the chain extender is 100:20~300; And / or, the mass ratio of the hydrophobic silane coupling agent to the hydrophilic substance is 100:5~15.
7. The modified silane coupling agent prepared by any one of claims 1-6.
8. The application of the modified silane coupling agent according to claim 7 in waterborne epoxy emulsion coatings.
9. A water-based epoxy emulsion coating, characterized in that, include: The modified silane coupling agent of claim 7 is dispersed in an oil phase in an "oil-in-water" structure in an aqueous epoxy emulsion coating.
10. The waterborne epoxy emulsion coating according to claim 9, characterized in that: The modified silane coupling agent in the waterborne epoxy emulsion coating is 0.3~1.5wt%, preferably 0.5~1.0wt.