A silane-modified polysiloxane coating composition and a method for preparing the same

Abstract

The application discloses a silane modified polysiloxane coating composition and a preparation method thereof, relates to the technical field of functional organic silicon protective coating, and comprises components A, B, C and D; by controlling the preparation sequence of the component A, low-boiling small molecules are removed after the chain extension reaction of the polysiloxane addition, then the residual addition catalytic activity is utilized to complete the end-capping of the vinyl functional alkoxy silane, and the residual addition catalytic activity is reduced after the end-capping, which is beneficial to reducing the low-boiling small molecule residues in the component A and improving the storage stability; when the coating composition is cured, the hydrolyzable alkoxy contained in the components A, B and C is hydrolyzed and condensed to form a siloxane crosslinking structure; the amino group in the component B and the epoxy group in the component C undergo ring-opening reaction to form a connection containing a beta-hydroxyl amine structure, so that the composition can be cured under room temperature and humidity conditions, and has good adhesion and water resistance.

Description

Technical Field

[0001] This invention relates to the field of functional organosilicon protective coatings, and in particular to a silane-modified polysiloxane coating composition and its preparation method. Background Technology

[0002] Single-component room temperature moisture-curing (RTV-1) silicone coatings use silane-terminated polysiloxanes as the base resin. Under sealed storage conditions, they maintain liquid stability. After being applied to the substrate surface, they rely on ambient moisture to trigger the hydrolysis and condensation of alkoxysilanes, which crosslink to form a polysiloxane coating film. Due to the high Si-O bond energy of the main chain, low surface energy, and excellent air permeability, this type of coating has been widely used in fields such as corrosion protection of building steel structures, concrete surface protection, electronic component coating, wind turbine blade coating, and flexible substrate surface treatment.

[0003] To improve the adhesion of silicone coatings to substrates such as metals, inorganic non-metals, and plastics, the art also commonly employs the formulation of coupling agents such as amino-functionalized alkoxysilanes, epoxy-functionalized alkoxysilanes, or acryloyloxy-functionalized alkoxysilanes. These agents utilize their polar functional groups to form chemical bonds or strong physical adsorption at the substrate interface, thereby enhancing the interfacial bonding strength of the coating under both dry and wet conditions.

[0004] However, existing technologies still have shortcomings. Existing single-component room temperature moisture-curing silicone coatings still struggle to achieve a good balance between low-boiling small molecule residues, storage stability, room temperature curing speed, substrate adhesion, water resistance, and coating mechanical properties. Furthermore, amino-functionalized silanes and epoxy-functionalized silanes are usually added only as coupling agents, and their reaction relationship with the silane-terminated polysiloxane host network lacks targeted design. Summary of the Invention

[0005] In a first aspect, the present invention provides a silane-modified polysiloxane coating composition comprising: component A, component B, component C, and component D; Based on 100 parts by weight of component A, component B is 1.2 parts by weight; Component B is γ-aminopropyltriethoxysilane, and component C is γ-(2,3-epoxypropoxy)propyltrimethoxysilane; The types and amounts of components C and D satisfy any of the following combinations: (1) The C component is 0.6 to 2.4 parts by weight, and the D component is 0.08 parts by weight of dibutyltin dilaurate; (2) The C component is 1.2 parts by weight and the D component is 0.08 parts by weight of tetraisopropyl titanate or bismuth neodecanoate; Component A is a silane-modified polysiloxane prepolymer containing a polysiloxane backbone and hydrolyzable alkoxysilane end groups, and is prepared in the following order: An addition reaction is carried out between linear organosilicones and hydrogen-containing polysiloxanes under the action of an addition catalyst; After the addition reaction is completed, the reaction system is subjected to a low-boiling small molecule removal treatment; After the removal of low-boiling small molecules, vinyl-functionalized alkoxysilane is added to the reaction system, so that the vinyl-functionalized alkoxysilane undergoes an addition-capping reaction with the Si-H groups retained in the hydrogen-containing polysiloxane under the action of the residual addition catalyst. After the addition capping reaction is completed, a terminator is added to the reaction system to reduce the activity of the residual platinum-based addition catalyst, thus obtaining component A.

[0006] Preferably, the organosilicon linear body is α,ω-divinyl polydimethylsiloxane; The hydrogen-containing polysiloxane is a hydrogen-terminated polydimethylsiloxane; The addition catalyst is a platinum-based addition catalyst; The terminator is triphenylphosphine; The vinyl-functionalized alkoxysilane is selected from vinyltrimethoxysilane or vinyltriethoxysilane.

[0007] Preferably, component A is prepared according to the following steps: Add 1000 parts by weight of α,ω-divinyl polydimethylsiloxane and 118 parts by weight of hydrogen-terminated polydimethylsiloxane to the reactor and stir for 30 min under nitrogen protection. The reaction system was heated to 72°C, and 0.18 parts by weight of a platinum-based addition catalyst were added. The reaction was carried out at 72–78°C for 2.5 h. After the addition reaction is complete, the reaction system is heated to 88℃ and subjected to reduced pressure treatment at -0.090 to -0.096 MPa for 1.5 h. The reaction system was cooled to 65°C, and 36 parts by weight of vinyltrimethoxysilane were added. The reaction was carried out at 65-70°C for 2 hours. Add 0.12 parts by weight of triphenylphosphine, stir for 40 min, then treat under reduced pressure for 30 min at -0.085 to -0.092 MPa, cool and filter to obtain component A.

[0008] Preferably, the coating composition is a homogeneous single-component system before curing; In the single-component system, component A constitutes the main resin phase, and components B and C serve as reactive silane components, which are uniformly mixed in the main resin phase.

[0009] Preferably, during the room temperature moisture curing process of the coating composition, ambient moisture causes hydrolyzable alkoxysilane end groups, ethoxysilane groups and methoxysilane groups to hydrolyze and generate silanol groups; In this process, component D catalyzes the condensation reaction between silanol groups, causing component A, at least a portion of component B, and at least a portion of component C to be interconnected through Si-O-Si bonds, forming a siloxane cross-linked structure with the polysiloxane chain segments of component A as the main backbone.

[0010] Preferably, during the room temperature moisture curing process, at least a portion of the amino groups in component B undergoes a ring-opening reaction with the epoxy groups in component C, forming a linkage structure containing a β-hydroxyamine structure between component B and component C. The connecting structure and the siloxane crosslinking structure coexist in the cured coating.

[0011] Preferably, the siloxane crosslinking structure is used to form the main network of the cured coating film, and at least a portion of components B and C are incorporated into the network structure mainly composed of polysiloxane segments; The connecting structure forms an additional connection between component B and component C, and introduces hydroxyl and amine polar structures into the cured coating, so that the cured coating has both the film-forming integrity of the siloxane crosslinking network and the polar effect provided by the β-hydroxyamine connecting structure.

[0012] In a second aspect, the present invention provides a method for preparing a silane-modified polysiloxane coating composition, comprising: After the preparation of component A is completed, component A is added to a dry stirring container under moisture-proof conditions. Under stirring, components B, C and D are added in sequence and mixed evenly to obtain a silane-modified polysiloxane coating composition that is in a uniform single-component state before curing.

[0013] The beneficial effects of this invention are as follows: By controlling the preparation sequence of component A, the invention removes low-boiling small molecules after the polysiloxane addition chain extension reaction, and then utilizes the residual addition catalytic activity to complete the vinyl-functionalized alkoxysilane end-capping. After end-capping, the residual addition catalytic activity is reduced, which is beneficial to reduce the residue of low-boiling small molecules in component A and improve storage stability. When the coating composition is cured, the hydrolyzable alkoxy groups contained in components A, B, and C undergo hydrolysis and condensation to form a siloxane cross-linked structure. The amino group in component B and the epoxy group in component C undergo a ring-opening reaction to form a link containing a β-hydroxyamine structure, which enables the composition to cure under room temperature and humidity conditions and has good adhesion and water resistance. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart illustrating the preparation of the silane-modified polysiloxane coating composition in a specific embodiment; Figure 2 This is a flowchart illustrating the preparation method of silane-modified polysiloxane prepolymer (component A) in a specific embodiment. Figure 3 This is a schematic diagram illustrating the formation of a double cross-linked structure during the room temperature moisture curing process of the coating in a specific embodiment. Detailed Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] Unless otherwise stated, all parts by weight in this application are parts by mass.

[0018] The term "homogeneous single-component system" as used in this application refers to components A, B, C, and D being premixed in the same container or the same construction packaging, and after mixing, no macroscopic stratification, sedimentation, or gelation occurs within a specified observation period. This statement does not imply that the components have completely identical concentration distributions at the molecular scale.

[0019] The term "main resin phase" as used in this application refers to a system in which component A is a continuous film-forming phase, components B and C are mixed as reactive silane components, and component D exists as a condensation catalyst.

[0020] During room temperature moisture curing, the hydrolyzable alkoxysilane end groups of component A, the ethoxysilane groups of component B, and the methoxysilane groups of component C undergo hydrolysis to generate silanol groups.

[0021] The aforementioned silanol groups undergo condensation with each other and with the silanol groups and the alkoxysilane groups that have not yet been hydrolyzed, forming a siloxane crosslinking structure with the polysiloxane chain segment of component A as the main body and at least a portion of components B and C participating therein.

[0022] At the same time, at least a portion of the amino groups in component B undergo a ring-opening reaction with the epoxy groups in component C, forming a link containing a β-hydroxyamine structure between components B and C.

[0023] The structural analysis of the curing reaction and the curing network described above is shown in Experimental Example 2 and Experimental Example 3.

[0024] The viscosity of the α,ω-divinyl polydimethylsiloxane used to prepare component A is preferably 1400–2200 mPa·s at 25°C, and the vinyl content is preferably 0.145–0.175 mmol·g. -1The preferred viscosity of the hydrogen-terminated polydimethylsiloxane at 25°C is 60–140 mPa·s, and the preferred Si-H content is 2.10–2.45 mmol·g. -1 The effective platinum content of the platinum-based addition catalyst is preferably 0.8 to 1.2 wt%, the purity of vinyltrimethoxysilane or vinyltriethoxysilane is preferably not less than 98.0 wt%, and the purity of triphenylphosphine is preferably not less than 99.0 wt%.

[0025] Example 1

[0026] This embodiment provides a silane-modified polysiloxane prepolymer as component A in the subsequent preparation of a silane-modified polysiloxane coating composition. Component A contains a polysiloxane backbone and hydrolyzable alkoxysilane end groups, and is prepared by an addition reaction between an organosilicon linear polymer and a hydrogen-containing polysiloxane, a low-boiling small molecule removal treatment, a vinyl-functionalized alkoxysilane end-capping reaction, and a treatment to reduce residual addition catalytic activity.

[0027] In this embodiment, α,ω-divinyl polydimethylsiloxane is selected as the organosilicon linear body, hydrogen-terminated polydimethylsiloxane is selected as the hydrogen-containing polysiloxane, platinum-based catalyst is selected as the addition catalyst, triphenylphosphine is selected as the terminator, and vinyltrimethoxysilane is selected as the vinyl-functionalized alkoxysilane.

[0028] The α,ω-divinyl polydimethylsiloxane used in this embodiment has a viscosity of 1680 mPa·s at 25°C and a vinyl content of 0.161 mmol·g. -1 The hydrogen-terminated polydimethylsiloxane has a viscosity of 92 mPa·s at 25°C and a Si-H content of 2.28 mmol·g. -1 The effective platinum content of the platinum-based addition catalyst is 1.05 wt%; the purity of vinyltrimethoxysilane is 99.2 wt% and the water content is 0.07 wt%; the purity of triphenylphosphine is 99.3 wt%.

[0029] Based on the above functional group content calculations, the molar ratio of Si-H to vinyl groups at the start of the addition reaction is approximately 1.67:1, ensuring that Si-H groups that can participate in subsequent end-capping reactions are retained after the chain extension reaction; while vinyltrimethoxysilane is added in excess relative to the theoretical residual Si-H.

[0030] During the addition chain extension process, the terminal vinyl groups of α,ω-divinyl polydimethylsiloxane undergo an addition reaction with the Si-H groups of the terminal hydrogen-containing polydimethylsiloxane. Since the Si-H groups are relatively in excess, the polysiloxane intermediate obtained after the addition chain extension still retains Si-H groups that can continue to participate in the end-capping reaction.

[0031] In this embodiment, 36 parts by weight of vinyltrimethoxysilane were added, corresponding to approximately 0.243 mol of vinyltrimethoxysilane. Vinyltrimethoxysilane was added in excess relative to the theoretically remaining Si-H groups after chain extension to promote the end-capping reaction of the remaining Si-H groups. The low-molecular-weight vinyltrimethoxysilane that did not participate in the reaction was at least partially removed in the subsequent vacuum treatment.

[0032] Specifically, 1000 parts by weight of α,ω-divinyl polydimethylsiloxane and 118 parts by weight of hydrogen-terminated polydimethylsiloxane were added to a reactor equipped with a mechanical stirrer, thermometer, nitrogen inlet and pressure reducing port. The mixture was stirred for 30 min under nitrogen protection to ensure uniform mixing. Subsequently, the reaction system was heated to 72 °C, and 0.18 parts by weight of platinum-based addition catalyst were added. The reaction temperature was controlled at 72–78 °C, and the reaction was carried out for 2.5 h to obtain the chain-extended polysiloxane intermediate.

[0033] Samples were taken every 30 minutes during the reaction, and characteristic absorption signals of vinyl groups and Si-H were detected using infrared spectroscopy. Each spectrum was first plotted at 1260 cm⁻¹. -1 The characteristic peak of Si-CH3 in the vicinity was normalized, and the normalized peak area at the beginning of the reaction was recorded as 1. After 2.5 h of reaction, the normalized peak area of ​​vinyl decreased to 0.081, while the normalized peak area of ​​Si-H remained at 0.428, indicating that most of the terminal vinyl groups had participated in the addition reaction, and that the system still retained Si-H groups that could participate in the subsequent end-capping reaction.

[0034] Table 1: Structural signal changes during the addition chain extension process in Example 1 0 1 1 1548 Uniform and transparent 0.5 0.664 0.803 1845 Uniform and transparent 1 0.371 0.642 2218 Uniform and transparent 1.5 0.192 0.533 2576 Uniform and transparent 2 0.096 0.458 2849 Uniform and transparent 2.5 0.081 0.428 2976 Uniform and transparent After the addition reaction is complete, the reaction system is heated to 88℃ and treated under reduced pressure of -0.090 to -0.096 MPa for 1.5 h to remove low-boiling small molecules, unreacted small molecule siloxanes, and some volatile impurities from the system.

[0035] After the removal of low-boiling small molecules, the reaction system is cooled to 65°C. Then, at 65-70°C, 36 parts by weight of vinyltrimethoxysilane are added to the reaction system, and the reaction is continued for 2 hours. Vinyltrimethoxysilane participates in the end-capping reaction under the action of the residual platinum addition catalyst, thereby introducing hydrolyzable methoxysilane end groups into the polysiloxane prepolymer.

[0036] During the end-capping reaction, samples were taken every 30 minutes to detect the characteristic absorption signal of Si-H. Each spectrum was first measured at 1260 cm⁻¹. -1The Si-CH3 characteristic peaks nearby were normalized, and the normalized Si-H peak area at the beginning of the end-capping reaction was recorded as 1. After 2 hours of reaction, the normalized Si-H peak area decreased to 0.064, which was 93.6% lower than at the beginning of the end-capping reaction. Based on this, it was determined that the end-capping reaction was basically completed.

[0037] Table 2: Si-H signal changes during the sealing process in Example 1 0 1 2928 transparent 0.5 0.482 3021 transparent 1 0.224 3096 transparent 1.5 0.103 3157 transparent 2 0.064 3192 Colorless to slightly yellow and transparent After the end-capping reaction was completed, 0.12 parts by weight of triphenylphosphine were added to the reaction system and the mixture was stirred for 40 min to reduce the residual platinum group addition catalytic activity.

[0038] Subsequently, the system was subjected to reduced pressure treatment for 30 minutes at -0.085 to -0.092 MPa to remove unreacted small molecule components. The system was then cooled to room temperature and filtered to obtain component A of this embodiment.

[0039] The obtained component A is a colorless to slightly yellow transparent viscous liquid with a viscosity of 3180 mPa·s at 25℃. Table 2 shows that 3192 mPa·s is the viscosity of the reaction system at the end of the 2-hour capping reaction, and 3180 mPa·s is the viscosity of component A after adding triphenylphosphine, undergoing another depressurization treatment, cooling, and filtration. The characteristic Si-H signal in the infrared spectrum of the obtained component A is reduced by more than 90% compared with the beginning of the capping reaction, and the alkoxysilane group-related signal is detected, indicating that vinyltrimethoxysilane participated in the capping reaction of the residual Si-H groups. The low-boiling residue, VOC content, and storage stability of the obtained component A are shown in Table 3.

[0040] Example 2

[0041] This embodiment provides another silane-modified polysiloxane prepolymer.

[0042] This embodiment is basically the same as Example 1 in terms of main raw material system, reaction equipment, addition chain extension conditions, low-boiling small molecule removal conditions, vinyl-functionalized alkoxysilane end-capping conditions, and residual addition catalytic activity reduction treatment conditions. The difference is: In this embodiment, vinyltriethoxysilane is used instead of vinyltrimethoxysilane in Example 1 for end-capping to obtain a silane-modified polysiloxane prepolymer containing hydrolyzable ethoxysilane end groups.

[0043] The performance ranges of α,ω-divinyl polydimethylsiloxane, hydrogen-terminated polydimethylsiloxane, platinum-based addition catalyst, and triphenylphosphine used in this embodiment are the same as those in Example 1. The purity of vinyltriethoxysilane is not less than 98.0 wt%, and the moisture content is not more than 0.20 wt%.

[0044] 48 parts by weight of vinyltriethoxysilane corresponds to approximately 0.252 mol, which has a similar vinyl molar amount to that of vinyltrimethoxysilane used in Example 1, and is used to cap the residual Si-H groups after chain extension.

[0045] Specifically, 1000 parts by weight of α,ω-divinyl polydimethylsiloxane and 118 parts by weight of hydrogen-terminated polydimethylsiloxane were added to a reactor and stirred for 30 min under nitrogen protection. Then, the temperature was raised to 72 °C, and 0.18 parts by weight of a platinum-based addition catalyst were added. The reaction temperature was controlled at 72–78 °C, and the reaction was carried out for 2.5 h to obtain the chain-extended polysiloxane intermediate.

[0046] After the addition reaction was completed, the low-boiling small molecule removal treatment was carried out in the same manner as in Example 1, that is, the reaction system was heated to 88°C and subjected to reduced pressure treatment at -0.090 to -0.096 MPa for 1.5 h; then the system was cooled to 65°C.

[0047] At 65–70 °C, 48 parts by weight of vinyltriethoxysilane were added to the reaction system and the reaction was continued for 2 hours. Vinyltriethoxysilane participated in the end-capping reaction under the action of residual platinum addition catalyst, thereby introducing hydrolyzable ethoxysilane end groups into the polysiloxane prepolymer.

[0048] After the end-capping reaction is completed, 0.12 parts by weight of triphenylphosphine are added to the reaction system and the mixture is stirred for 40 min. Triphenylphosphine coordinates with the residual platinum-based catalytic active center, which reduces the residual addition catalytic activity and thus reduces the possibility of further addition reactions or other viscosity increases induced by the residual platinum catalytic activity during storage.

[0049] Subsequently, the system was subjected to reduced pressure treatment for 30 minutes at -0.085 to -0.092 MPa to remove unreacted small molecule components. The system was then cooled to room temperature and filtered to obtain component A of this embodiment.

[0050] The obtained component A is a colorless to slightly yellow transparent viscous liquid, and its specific performance results are shown in Table 3.

[0051] To illustrate the effects of low-boiling small molecule removal treatment and residual addition catalytic activity reduction treatment on the stability of component A, control sample 1 and control sample 2 are set up in Table 3.

[0052] The difference between Comparative Sample 1 and Example 1 is that the low-boiling small molecule removal treatment is not performed. The difference between Comparative Sample 2 and Example 1 is that, after the vinyltrimethoxysilane end-capping reaction is completed, triphenylphosphine is not added to reduce the residual addition catalytic activity.

[0053] Apart from the differences mentioned above, the types and amounts of raw materials used in Comparative Sample 1 and Comparative Sample 2, as well as the other process conditions, are the same as in Example 1.

[0054] Low-boiling residue was calculated as the mass difference of the sample before and after vacuum treatment to constant weight at 105±2℃ and -0.090 to -0.096 MPa; viscosity, VOC content and storage conditions were determined using conventional methods in the field.

[0055] Table 3: Preparation conditions and basic performance results of component A Example 1 α,ω-Divinyl polydimethylsiloxane Hydrogen-terminated polydimethylsiloxane Vinyltrimethoxysilane yes yes 0.26 3180 8.7 41 Transparent, without layering, and without gel. Example 2 α,ω-Divinyl polydimethylsiloxane Hydrogen-terminated polydimethylsiloxane Vinyltriethoxysilane yes yes 0.29 3350 9.8 44 Transparent, without layering, and without gel. Comparison Sample 1 α,ω-Divinyl polydimethylsiloxane Hydrogen-terminated polydimethylsiloxane Vinyltrimethoxysilane no yes 1.18 2860 17.9 86 Slightly volatile odor, subsequent film formation with localized pinholes Comparison Sample 2 α,ω-Divinyl polydimethylsiloxane Hydrogen-terminated polydimethylsiloxane Vinyltrimethoxysilane yes no 0.31 3260 46.5 45 Slight thickening and decreased leveling properties after storage As shown in Table 3, both Examples 1 and 2 underwent low-boiling small molecule removal treatment and residual addition catalytic activity reduction treatment. The low-boiling residual amounts of the obtained component A were 0.26% and 0.29%, respectively, and the viscosity change rates after storage at 50°C for 30 days were 8.7% and 9.8%, respectively. This indicates that both vinyl-functionalized alkoxysilanes can be used for end-capping of component A and can obtain silane-modified polysiloxane prepolymers with good storage stability.

[0056] Compared to Example 1, control sample 1, which did not undergo low-boiling small molecule removal treatment, had its low-boiling residue increased to 1.18% and its VOC content increased to 86 g·L⁻¹. -1 The results show that the removal of low-boiling small molecules can effectively reduce the volatile residues in component A and reduce the appearance defects in the subsequent coating and curing processes.

[0057] Although Comparative Sample 2 underwent low-boiling small molecule removal treatment, its low-boiling residual amount was 0.31%, which was close to that of Example 1. However, due to the lack of addition catalyst termination treatment, the viscosity change rate increased to 46.5% after storage at 50°C for 30 days, and slight thickening and decreased leveling properties were observed after storage. This result indicates that addition catalyst termination treatment can suppress the continued induction of side reactions by residual platinum catalysts during storage, thereby improving the storage stability of component A.

[0058] Therefore, the results in Table 3 show that, under the raw materials and process conditions used in this embodiment, the removal of low-boiling small molecules is beneficial to reducing the amount of low-boiling residue and VOC content, and the treatment to reduce the residual addition catalytic activity is beneficial to controlling the viscosity increase during storage. By sequentially performing addition chain extension, removal of low-boiling small molecules, end-capping with vinyl-functionalized alkoxysilane, and treatment to reduce the residual addition catalytic activity, it is possible to balance the control of low-boiling residue of component A, storage stability, and subsequent moisture curing reaction activity.

[0059] Example 3

[0060] The formulation and performance results of this embodiment are shown in Table 4.

[0061] This embodiment provides a silane-modified polysiloxane coating composition, which uses component A obtained in the aforementioned Example 1 as the base resin, selects γ-aminopropyltriethoxysilane as component B, selects γ-(2,3-epoxypropoxy)propyltrimethoxysilane as component C, and selects dibutyltin dilaurate as component D.

[0062] This embodiment is a basic formulation example of the composition of the present invention.

[0063] This embodiment is applicable to the preparation of a single-component room temperature moisture-curing coating for general industrial protection on the surface of sandblasted steel plate; the coating is required to cure by ambient moisture after a single scraping or spraying, and to have good adhesion, water resistance and surface integrity after curing.

[0064] In the specific preparation, 100 parts by weight of component A obtained in Example 1 were added to a dry stirring container and stirred at 300 r / min for 10 min at 25°C; then 1.2 parts by weight of γ-aminopropyltriethoxysilane were added and stirring was continued for 8 min; then 1.2 parts by weight of γ-(2,3-epoxypropoxy)propyltrimethoxysilane were added and stirring was continued for 10 min; finally, 0.08 parts by weight of dibutyltin dilaurate were added and stirred for 15 min under moisture-proof conditions to obtain a uniform transparent to slightly turbid transparent silane-modified polysiloxane coating composition.

[0065] In this embodiment, the weight ratio of component B to component C is 1:1, which is a preferred component ratio of the present invention.

[0066] The obtained coating composition was applied to the surface of a sandblasted steel plate and a clean glass plate. The wet film thickness of the coating used for structural analysis was controlled to be approximately 120 μm. Specimens used for adhesion, water resistance and other routine performance tests were prepared separately according to the conditions in Table 4 and cured at room temperature and humidity at approximately 23°C and 55% relative humidity.

[0067] In this embodiment, component A is used in an amount of 100 parts by weight, constituting the continuous main resin phase of the composition; components B, C and D are used in relatively low amounts and are mixed into component A by sequential addition and stirring. After mixing, the resulting composition is in a uniform transparent to slightly turbid transparent state. After standing for 24 hours, no macroscopic layering, sedimentation and gelation were observed, forming a uniform single-component system before curing.

[0068] After application, ambient moisture causes the hydrolyzable methoxysilane end groups of component A, the ethoxysilane groups of component B, and the methoxysilane groups of component C to hydrolyze and generate silanol groups. Under the catalysis of dibutyltin dilaurate, the generated silanol groups condense with each other and with the incompletely hydrolyzed alkoxysilane groups to form a Si-O-Si linkage structure.

[0069] Through the above hydrolysis and condensation reaction, a siloxane cross-linked structure is formed with the polysiloxane segments of component A as the main body, and at least a portion of component B and at least a portion of component C participate in the formation of the cured network.

[0070] At the same time, at least a portion of the amino groups in component B undergo a ring-opening reaction with the epoxy groups in component C, forming a linking structure containing a β-hydroxyamine structure between component B and component C.

[0071] The aforementioned siloxane crosslinking structure constitutes the main network of the cured coating film, while the β-hydroxyamine linking structure forms an additional link between component B and component C, and introduces hydroxyl groups and nitrogen-containing polar structures into the cured coating film.

[0072] Example 4

[0073] The difference between this embodiment and Example 3 is that the amount of component C, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, is 0.6 parts by weight; the types and amounts of components A and B, the type and amount of component D, the order of adding components B, C, and D, the stirring conditions, the film-forming conditions, and the curing conditions are all the same as in Example 3.

[0074] The resulting composition was uniform and transparent to slightly turbid and transparent. No layering, sedimentation or gelation was observed after standing in a sealed container for 24 hours.

[0075] The formulation and performance results are shown in Table 4.

[0076] Example 5

[0077] The difference between this embodiment and Example 3 is that the amount of component C, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, is 2.4 parts by weight. The other raw materials, their amounts, mixing steps, film-forming conditions, and curing conditions are the same as in Example 3.

[0078] After mixing, the resulting composition was a homogeneous, slightly turbid, and transparent liquid, and no macroscopic layering or gelation was observed; due to the higher amount of component C, its initial viscosity was slightly lower than that of Example 3.

[0079] Example 6

[0080] This embodiment provides silane-modified polysiloxane coating compositions using different condensation catalysts as component D, to illustrate that organotin catalysts, titanate catalysts, and bismuth-based catalysts can all be used as component D in the compositions of this invention.

[0081] In this embodiment, component A is the silane-modified polysiloxane prepolymer obtained in Example 1, component B is γ-aminopropyltriethoxysilane, and component C is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0082] Except for the different types of component D, the mixing method, coating method and curing conditions in this embodiment are the same as in Example 3.

[0083] This embodiment includes Embodiment 6A and Embodiment 6B.

[0084] In Example 6A, 100 parts by weight of component A obtained in Example 1 were taken, and 1.2 parts by weight of γ-aminopropyltriethoxysilane were added and stirred for 8 min; then 1.2 parts by weight of γ-(2,3-epoxypropoxy)propyltrimethoxysilane were added and stirred for another 10 min; finally, 0.08 parts by weight of tetraisopropyl titanate were added and stirred for 15 min to obtain a silane-modified polysiloxane coating composition.

[0085] The resulting composition was a uniform, slightly yellow, transparent liquid. No macroscopic layering or gelation was observed after standing for 24 hours.

[0086] The difference between Example 6B and Example 6A is that tetraisopropyl titanate is replaced with 0.08 parts by weight of bismuth neodecanoate, while the other components and amounts remain unchanged.

[0087] The composition obtained in Example 6B was a homogeneous, slightly turbid, and transparent liquid. After standing for 24 hours, no macroscopic layering or gelation was observed. It showed slight local opalescence but no visible sedimentation.

[0088] Example 7

[0089] This embodiment uses component A containing hydrolyzable ethoxysilane end groups, obtained in Example 2, to prepare a silane-modified polysiloxane coating composition.

[0090] 100 parts by weight of component A obtained in Example 2 were added to a dry stirring container and stirred for 10 min at 25°C and 300 r / min. 1.2 parts by weight of γ-aminopropyltriethoxysilane were added and stirring was continued for 8 min. 1.2 parts by weight of γ-(2,3-epoxypropoxy)propyltrimethoxysilane were added and stirring was continued for 10 min. Finally, 0.08 parts by weight of dibutyltin dilaurate were added and stirring was continued for 15 min under moisture-proof conditions to obtain the silane-modified polysiloxane coating composition.

[0091] After mixing, the resulting composition was uniform, slightly yellow and transparent to slightly cloudy and transparent. No macroscopic layering or gelation was observed. The coating was prepared and tested in the same way as in Example 3. Its formulation, pre-curing state and performance results are listed in Table 4.

[0092] To illustrate the importance of the coexistence of components B and C for the overall performance of the coating and subsequent mechanism verification, comparative sample 3 and comparative sample 4 are set up in Table 4.

[0093] The difference between Comparative Sample 3 and Example 3 is that Component B is not added, but only Components C and D are added; the difference between Comparative Sample 4 and Example 3 is that Component C is not added, but only Components B and D are added.

[0094] Apart from the differences mentioned above, the source of component A, the type and amount of component D, the mixing method, the coating method, and the curing conditions of comparative sample 3 and comparative sample 4 are the same as those of Example 3.

[0095] The surface drying time and complete drying time of the coating composition were determined according to GB / T 1728—2020; adhesion was determined by cross-cut test according to GB / T 9286—2021; pencil hardness was determined according to GB / T 6739—2022; water resistance was evaluated according to GB / T 1733—1993; and the tensile strength and elongation at break of the free film were determined according to GB / T 528—2009.

[0096] Adhesion testing was conducted using sandblasted steel plates, with a dry film thickness controlled at 80–100 μm and a cross-cut spacing of 2 mm. Water resistance testing employed a complete immersion method at a water temperature of 23 ± 2℃; the free film thickness was 1 ± 0.1 mm, and the tensile speed was 200 mm·min. -1 Each test has 3 parallel samples. The surface drying time, actual drying time, tensile strength and elongation at break in the table are the average values ​​of the parallel samples.

[0097] Table 4: Coating Composition Formulation, Pre-Cure State, and Conventional Performance Results Example 3 Component A obtained in Example 1, 100 parts KH-550, 1.2 KH-560, 1.2 Dibutyltin dilaurate, 0.08 1:1 Uniform and transparent to slightly cloudy, without layering or gelation. 34 7.6 0 No bubbling, no peeling, slight loss of gloss H 2.86 148 Example 4 Component A obtained in Example 1, 100 parts KH-550, 1.2 KH-560, 0.6 Dibutyltin dilaurate, 0.08 1:0.5 Uniform and transparent, without layering or gelation. 41 8.9 0～1 No peeling, slight loss of luster at the edges HB~H 2.64 156 Example 5 Component A obtained in Example 1, 100 parts KH-550, 1.2 KH-560, 2.4 Dibutyltin dilaurate, 0.08 1:2 Uniform, slightly turbid and transparent, without layering or gelation. 31 7.4 0 No bubbling, no peeling H 2.93 137 Example 6A Component A obtained in Example 1, 100 parts KH-550, 1.2 KH-560, 1.2 Tetraisopropyl titanate, 0.08 1:1 Uniform, slightly yellow and transparent, without layering or gel. 39 8.4 0 No bubbling, no peeling, slight loss of gloss H 2.74 152 Example 6B Component A obtained in Example 1, 100 parts KH-550, 1.2 KH-560, 1.2 Bismuth neodecanoate, 0.08 1:1 Uniform, slightly turbid and transparent, with a slight opalescence, no sedimentation, no gelation. 43 9.1 0～1 No peeling, slight whitening in some areas HB~H 2.63 158 Example 7 Component A obtained in Example 2, 100 parts KH-550, 1.2 KH-560, 1.2 Dibutyltin dilaurate, 0.08 1:1 Uniform, slightly yellow and transparent to slightly cloudy transparent, without layering or gel. 38 8.3 0～1 No bubbling, no peeling, slight loss of gloss HB~H 2.71 154 Comparison Sample 3 Component A obtained in Example 1, 100 parts 0 KH-560, 1.2 Dibutyltin dilaurate, 0.08 — Uniform and transparent, without layering or gelation. 52 12.4 2 Slight blistering at the edges, with localized whitening. HB 2.12 171 Comparison Sample 4 Component A obtained in Example 1, 100 parts KH-550, 1.2 0 Dibutyltin dilaurate, 0.08 — Uniform, slightly turbid and transparent, without layering or gelation. 27 8.9 1 Slight whitening, localized decrease in adhesion HB~H 2.34 126 Note: KH-550 represents γ-aminopropyltriethoxysilane, KH-560 represents γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and the state before curing in the table is the macroscopic observation result after the composition is mixed and left to stand under sealed conditions for 24 hours; "0~1 grade" in the table means that the adhesion results of the three parallel samples are distributed between grade 0 and grade 1; "HB~H" means that the pencil hardness measured by the three parallel samples is distributed between HB and H.

[0098] As shown in Table 4, Examples 3-5 were able to form continuous coatings under room temperature and humidity conditions. When the amount of component C increased from 0.6 parts by weight to 2.4 parts by weight, the surface drying time, complete drying time, tensile strength, and elongation at break changed accordingly, indicating that the amount of component C can adjust the curing speed and mechanical properties of the coating.

[0099] Example 4 has a relatively long surface drying and hard drying time and a high elongation at break, indicating that a lower C component dosage is beneficial for maintaining a longer open time and flexibility during construction. Example 5 has a shorter surface drying time and higher tensile strength, indicating that a higher C component dosage can improve curing speed and coating strength.

[0100] Examples 6A and 6B used tetraisopropyl titanate and bismuth neodecanoate as component D, respectively. The resulting compositions were able to complete room temperature moisture curing, indicating that the above catalysts can catalyze the hydrolysis-condensation curing of the compositions of the present invention.

[0101] Example 7 uses Component A containing hydrolyzable ethoxysilane end groups prepared in Example 2. Compared with Example 3, the surface drying time and actual drying time of Example 7 are slightly prolonged, the tensile strength is slightly decreased, and the elongation at break is slightly increased, but it still achieves an adhesion grade of 0-1. After 168 hours of water resistance, there is no blistering or peeling. This result indicates that Component A obtained by end-capping with vinyltriethoxysilane can also be used to prepare the silane-modified polysiloxane coating composition of the present invention.

[0102] Compared to Example 3, Comparative Sample 3 lacked component B, resulting in a significant decrease in its adhesion and post-water resistance. Comparative Sample 4 lacked component C, leading to changes in its adhesion, post-water resistance, and elongation at break. These results indicate that the coexistence of components B and C is beneficial for achieving a comprehensive balance between adhesion, water resistance, and mechanical properties in the resulting coating.

[0103] Table 4 directly reflects the correspondence between changes in composition and changes in coating performance. The specific chemical bonding structure was further verified by Experiment 2 and Experiment 3.

[0104] Experimental Example 1 This test example is used to evaluate the single-component state and storage stability of the coating composition before curing.

[0105] Take the coating compositions obtained in Examples 3 to 7 respectively, put them into dry and sealed containers of the same specifications, store one group of samples at 25°C for 30 days, and store the other group of samples at 50°C for 14 days.

[0106] Observe for stratification, sedimentation, clumping, and gelation before and after storage, and test the viscosity at 25°C. The viscosity change rate is calculated according to the following formula: Viscosity change rate = (Viscosity after storage - Initial viscosity) / Initial viscosity × 100%.

[0107] No macroscopic stratification, sedimentation, or gelation was observed in any of the samples after storage at 25℃ for 30 days. The appearance after storage in Table 5 is the result of observation after storage at 50℃ for 14 days and then restoration to 25℃. Table 5 is as follows: Table 5: Individual Component States and Storage Stability of Coating Compositions Before Curing Example 3 2925 5.8 11.9 Uniform, without layering or gelation Example 4 3010 4.9 10.7 Uniform and transparent, without layering, sedimentation, or gelation. Example 5 2795 7.6 15.2 Slightly turbid and transparent, without layering, sedimentation, or gelation. Example 6A 2968 6.7 13.8 Uniform, slightly yellow and transparent, without layering, sedimentation, or gelation. Example 6B 3076 8.4 16.6 Slightly opalescent, no stratification, no sedimentation, no gelation. Example 7 3165 7.2 14.5 Uniform, slightly yellow and transparent, without layering, sedimentation, or gelation. As can be seen from Table 5, the compositions obtained in Examples 3 to 7 all maintained a uniform state of single packaging before curing, and no macroscopic layering or gelation occurred after storage. Different amounts of component C and different condensation catalysts had a certain impact on the viscosity change rate. Among them, Example 6B, which used bismuth neodecanoate, showed a relatively large viscosity change after accelerated storage, but still remained flowable and gel-free.

[0108] Experimental Example 2 This experimental example is used to verify the amino-epoxy ring-opening reaction between components B and C.

[0109] The cured coatings obtained in Examples 3, 4, 5, 6A, 6B and 7 were selected as test objects. Comparative sample 3 and comparative sample 4 were also set up. Each sample was prepared according to the same wet film thickness and curing conditions.

[0110] The changes in the characteristic absorption peaks of epoxy groups and the related absorption peaks of hydroxyl groups were detected by ATR-FTIR at 1260 cm⁻¹. -1 The nearby Si-CH3 characteristic peak was used as a normalized internal standard, with a value of 910±5 cm⁻¹. -1 The attenuation ratio of the epoxy group characteristic peak was calculated based on the area of ​​the characteristic peak of the epoxy group in the vicinity; using the area of ​​the characteristic peak of the epoxy group in the range of 3200–3600 cm⁻¹. -1 The change in the normalized peak area of ​​a region is used to evaluate the hydroxyl-related signal.

[0111] For each formulation, the area of ​​the epoxy group peak after normalization of the Si-CH3 characteristic peak in the composition before curing is denoted as E0, and the area of ​​the epoxy group peak after normalization in the same manner in the coating film after 24 hours of curing is denoted as E1. The attenuation ratio of the epoxy group characteristic peak is calculated according to the following formula: The reduction ratio of the characteristic peak of epoxy group = (E0 - E1) / E0 × 100%.

[0112] To help confirm the ring-opening reaction of amino-epoxy, solid ¹³C direct-excitation magic-angle rotational NMR was performed on the cured sample, and spectra were acquired under the same pulse conditions, rotational speed and sufficient relaxation delay.

[0113] For each formulation, the ratio of the signal integral area in the 65–75 ppm region to the signal integral area of ​​the propyl segment internal standard in the 10–35 ppm region was calculated in the samples before and after curing, and the difference between the area ratios before and after curing was taken as the signal area ratio of oxygen-containing carbon related to the ring-opening reaction.

[0114] The test results are shown in Table 6.

[0115] Table 6: Results of the analysis of the ring-opening reaction of amino-epoxy compounds Example 3 69.8±2.7 26.1±2.1 0.24±0.02 A ring-opening reaction clearly occurred. Example 4 61.9±3.4 20.6±2.5 0.18±0.03 Ring-opening reaction occurs Example 5 75.6±2.3 29.8±2.7 0.29±0.02 High degree of open-loop Example 6A 66.2±3.1 24.0±2.4 0.22±0.02 Ring-opening reaction occurs Example 6B 64.5±3.6 22.8±2.9 0.21±0.03 Ring-opening reaction occurs Example 7 67.1±3 24.6±2.3 0.22±0.02 Ring-opening reaction occurs Comparison sample 3, without B 11.7±1.8 6.1±1.4 0.03±0.01 The epoxy groups changed relatively little. Comparison sample 4, without C not applicable 3.0±1.0 0.02±0.01 Lacking epoxy reaction sites As shown in Table 6, the characteristic peaks of epoxy groups in Examples 3 to 7 were significantly weakened, while the hydroxyl-related absorption region was enhanced, and a new signal corresponding to the hydroxyl-containing carbon structure after the epoxy ring opening appeared in solid ¹³C NMR. The characteristic peaks of epoxy groups in Comparative Sample 3 were less affected because it did not contain component B. Comparative Sample 4 did not contain component C and did not have epoxy reaction sites.

[0116] The above results collectively support that during the room temperature moisture curing process of the composition of the present invention, at least a portion of the amino groups in component B undergoes a ring-opening reaction with the epoxy groups in component C, forming a linkage structure containing a β-hydroxyamine structure.

[0117] The hydroxyl-related infrared absorption may also include contributions from silanol groups and adsorbed water. Therefore, this experiment does not determine the structure of β-hydroxyamine solely based on the broad peak of hydroxyl groups, but rather combines epoxy group consumption and solid ¹³C NMR signals for a comprehensive judgment.

[0118] Experimental Example 3 This experimental example is used to verify the siloxane crosslinking structure and the participation of components B and C in the curing network.

[0119] The cured coatings obtained in Examples 3, 4, 5, 6A, 6B and 7 were selected as test objects, and control samples 3, 4 and 5 were set up.

[0120] Comparative sample 3 did not contain component B, and comparative sample 4 did not contain component C; comparative sample 5 contained only 100 parts by weight of component A and 0.08 parts by weight of dibutyltin dilaurate, without the addition of components B and C. The remaining film-forming and curing conditions of comparative samples 3, 4, and 5 were the same as those in Example 3.

[0121] After curing, the coating film is cut into small pieces no larger than 5mm × 5mm and placed in anhydrous toluene for Soxhlet extraction for 12 hours to remove unreacted, unconnected to insoluble networks or components existing in the form of soluble oligomers.

[0122] After extraction, the insoluble gel was dried to constant weight under vacuum at 80°C, and the gel content was calculated according to the following formula: Gel content = (dry weight after extraction / dry weight before extraction) × 100%.

[0123] Three parallel samples were set up for each sample. The gel content in the table is the average value and standard deviation of the three parallel samples.

[0124] The nitrogen (N) content in the insoluble gel after extraction was determined by elemental analysis to evaluate whether the nitrogen-containing structure from component B was retained in the insoluble network. Free γ-aminopropyltriethoxysilane and γ-(2,3-epoxypropoxy)propyltrimethoxysilane in the extract were detected by gas chromatography-mass spectrometry.

[0125] The insoluble gel after extraction and drying to constant weight was subjected to solid ¹³C MAS nuclear magnetic resonance testing.

[0126] Under the same test parameters, baseline correction and peak area integration were performed on the spectra of each sample.

[0127] Using the integrated area of ​​the Si-CH3 carbon signal of the polydimethylsiloxane segment in component A within the -2 to 3 ppm region as a normalized internal standard, and the integrated area of ​​the ether bond carbon from component C and the hydroxyl-containing carbon structure after ring opening of the epoxy resin within the 67 to 76 ppm region as the characteristic signal of component C, the characteristic carbon signal area ratio SC of component C is calculated according to the following formula: SC = A 67-76 / A -2-3 .

[0128] Among them, A 67-76 A is the integral area of ​​the signal in the 67–76 ppm region. -2-3 The integral area of ​​the Si-CH3 signal in the -2 to 3 ppm region.

[0129] The attribution of the characteristic signals of component C is confirmed in the following way: The characteristic signal of component C was assigned using the uncured spectrum of component C as a peak position reference, and control samples 4 and 5, which do not contain component C, as background controls. When the SC value of the extracted gel was significantly higher than that of control samples 4 and 5, it was considered that there was an organic structure from component C in the gel.

[0130] Further solid-state 29Si MAS nuclear magnetic resonance (NMR) analysis was performed on the extracted insoluble gel, and peak fitting was performed on the T¹, T², and T³ signals of the organotrifunctional silane, where: T¹ represents the R—Si(OSi)(OH or OR)2 structure, with its chemical shift mainly located between -47 and -52 ppm; T² represents the R—Si(OSi)2(OH or OR) structure, with its chemical shift mainly located between -55 and -61 ppm; T³ represents the R-Si(OSi)3 structure, with its chemical shift mainly located between -64 and -70 ppm.

[0131] The degree of condensation αT of the organic trifunctional silane T unit is calculated using the following formula: αT=(IT¹+2IT²+3IT³) / [3×(IT¹+IT²+IT³)]×100%.

[0132] Wherein, IT¹, IT², and IT³ are the integral areas of the structural signals of T¹, T², and T³, respectively. The higher αT is, the higher the average degree of condensation of the organic trifunctional silane group.

[0133] Since the alkoxysilane end groups of component A, as well as components B and C, can all generate T-structure signals, αT is only used to evaluate the overall degree of condensation of the organic trifunctional silane in the cured network. It is not used to determine which component forms the T-structure. Whether component C participates in the insoluble cured network should be judged comprehensively by combining SC, αT, gel content, and the content of free C component in the extract.

[0134] In addition, ATR-FTIR was used to detect the Si-O-Si related absorption signals in the extracted insoluble gel. Considering that the polysiloxane backbone of component A itself contains a large number of Si-O-Si structures, the ATR-FTIR results are only used as auxiliary evidence of the existence of the siloxane network and are not used alone to prove that a specific Si-O-Si connection mode is formed between component C and component A.

[0135] The test results are shown in Tables 7 and 8.

[0136] Table 7: Results of Gel Content and Extractable Components Analysis of Cured Coating Film Example 3 89.4±1.2 0.184±0.009 0.07±0.01 0.09±0.02 Example 4 86.1±1.5 0.198±0.011 0.10±0.02 0.06±0.01 Example 5 91.8±0.9 0.162±0.008 0.05±0.01 0.16±0.03 Example 6A 88.2±1.3 0.176±0.010 0.08±0.02 0.10±0.02 Example 6B 87.6±1.6 0.181±0.012 0.09±0.02 0.12±0.03 Example 7 88.7±1.3 0.179±0.010 0.08±0.02 0.11±0.02 Comparison sample 3, without B 82.2±1.7 Not detected not applicable 0.24±0.04 Comparison sample 4, without C 83.5±1.4 0.207±0.013 0.19±0.03 not applicable Comparison sample 5, excluding B and C 76.8±1.8 Not detected not applicable not applicable Table 8: Characteristic signals of C component source and degree of condensation of organotrifunctional silanes in the extracted insoluble gel. Example 3 0.118±0.009 82.4±1.6 A clear signal originating from component C was detected in the gel, indicating a high degree of condensation of the T units. Example 4 0.064±0.006 78.6±1.9 When the amount of component C is low, the corresponding characteristic signal decreases. Example 5 0.196±0.014 85.1±1.4 A higher dosage of component C resulted in improved characteristic signals and degree of condensation. Example 6A 0.113±0.008 81.6±1.8 A clear signal originating from component C was detected. Example 6B 0.109±0.010 80.7±2.0 A clear signal originating from component C was detected. Example 7 0.115±0.008 81.9±1.7 The signal originating from component C was still detected when using component A with an ethoxy-terminated group. Comparison sample 3, without B 0.091±0.008 75.2±2.2 The C-component signal was detected in the gel, and the organic trifunctional silanes in the system showed a certain degree of condensation, but the overall gel content and the degree of condensation of the T units were low. Comparison sample 4, without C 0.006±0.002 73.6±2.0 Background signal only Comparison sample 5, excluding B and C 0.004±0.001 69.8±2.3 Only background signal and A-component end-group condensation signal As can be seen from Table 7, the gel content of the cured coatings obtained in Examples 3 to 7 is 86.1% to 91.8%, which is higher than that of the control sample 5 which does not contain components B and C. N element can still be detected in the insoluble gel after extraction, and the content of free component B in the extract is low, indicating that at least a portion of the nitrogen-containing structure from component B is retained in the insoluble cured network.

[0137] The content of free C component in the extracts of Examples 3-7 was 0.06wt%-0.16wt%, which was significantly lower than that of control sample 3, which did not contain component B. This result indicates that in the examples where components B and C coexisted, the proportion of C component extracted in the form of unreacted parent material was relatively low.

[0138] As can be seen from Table 8, the characteristic carbon signal area ratio (SC) of component C in the insoluble gels extracted in Examples 3-7 was 0.064-0.196, which was significantly higher than that of control samples 4 and 5, which did not contain component C.

[0139] Specifically, in Examples 4, 3 and 5, the amount of component C was 0.6 parts by weight, 1.2 parts by weight and 2.4 parts by weight, respectively, and their SC values ​​were 0.064, 0.118 and 0.196, respectively. The overall trend was upward as the amount of component C increased.

[0140] The above results indicate that the characteristic signal in the 67–76 ppm region corresponds to the amount of C component added, and can be used to characterize the ether-bonded carbon and the oxygen-containing carbon structure of the C component in the gel after extraction.

[0141] The degree of condensation αT of the organic trifunctional silane T units in Examples 3-7 was 78.6%-85.1%, indicating that the average degree of condensation of the organic trifunctional silane groups in the cured coating film was relatively high.

[0142] Although the control sample 3 does not contain component B, it still contains component C. Therefore, the characteristic carbon signal of component C can be detected in the gel after extraction. Its T unit condensation degree is 75.2%, indicating that the trimethoxysilane group of component C itself can also participate in hydrolysis and condensation.

[0143] Based on the high gel content, characteristic carbon signals of component C in the extracted gel, T² and T³ condensation structures of the organic trifunctional silane, and low extraction amount of free component C in Examples 3-7, it can be concluded that at least a portion of the organic structure derived from component C is retained in the insoluble siloxane-based solidified network, and that the trimethoxysilane group of component C participates in the hydrolysis-condensation reaction.

[0144] The above results support that at least some of the trimethoxysilane groups in component C participate in the formation of the siloxane network; further, combined with the detection results of the amino-epoxy ring-opening reaction in Experimental Example 2, it can be shown that at least some of the epoxy groups in component C undergo a ring-opening reaction with the amino group in component B to form an additional link containing a β-hydroxyamine structure.

[0145] Further combining the detection results of the amino-epoxy ring-opening reaction in Test Example 2, it can be confirmed that during the curing process of the composition of the present invention, the detection results of the amino-epoxy ring-opening reaction in Test Example 2 are used.

[0146] The above results support the participation of at least a portion of the trimethoxysilane groups in component C in the formation of the siloxane network, and support the ring-opening reaction of at least a portion of the epoxy groups in component C with the amino groups in component B to form additional linkages containing β-hydroxyamine structures.

[0147] It should be noted that the results of this experiment are used to prove that the source structure of component C participates in the formation of the insoluble solidification network, and are not used to limit the specific connection position of each component C molecule, nor do they indicate that all components C directly form a unique form of A-Si-O-Si-C connection with component A.

[0148] The cured network may also contain siloxane condensation structures between components C and B, as well as a small amount of self-condensation structures of component C.

[0149] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A silane-modified polysiloxane coating composition, characterized in that, include: Components A, B, C, and D; Based on 100 parts by weight of component A, component B is 1.2 parts by weight; Component B is γ-aminopropyltriethoxysilane, and component C is γ-(2,3-epoxypropoxy)propyltrimethoxysilane; The types and amounts of components C and D satisfy any of the following combinations: (1) The C component is 0.6 to 2.4 parts by weight, and the D component is 0.08 parts by weight of dibutyltin dilaurate; (2) The C component is 1.2 parts by weight and the D component is 0.08 parts by weight of tetraisopropyl titanate or bismuth neodecanoate; Component A is a silane-modified polysiloxane prepolymer containing a polysiloxane backbone and hydrolyzable alkoxysilane end groups, and is prepared in the following order: An addition reaction is carried out between linear organosilicones and hydrogen-containing polysiloxanes under the action of an addition catalyst; After the addition reaction is completed, the reaction system is subjected to a low-boiling small molecule removal treatment; After the removal of low-boiling small molecules, vinyl-functionalized alkoxysilane is added to the reaction system, so that the vinyl-functionalized alkoxysilane undergoes an addition-capping reaction with the Si-H groups retained in the hydrogen-containing polysiloxane under the action of the residual addition catalyst. After the addition capping reaction is completed, a terminator is added to the reaction system to reduce the activity of the residual platinum-based addition catalyst, thus obtaining component A.

2. The silane-modified polysiloxane coating composition according to claim 1, characterized in that, The organosilicon linear body is α,ω-divinyl polydimethylsiloxane; The hydrogen-containing polysiloxane is a hydrogen-terminated polydimethylsiloxane; The addition catalyst is a platinum-based addition catalyst; The terminator is triphenylphosphine; The vinyl-functionalized alkoxysilane is selected from vinyltrimethoxysilane or vinyltriethoxysilane.

3. The silane-modified polysiloxane coating composition according to claim 2, characterized in that, Component A is prepared according to the following steps: Add 1000 parts by weight of α,ω-divinyl polydimethylsiloxane and 118 parts by weight of hydrogen-terminated polydimethylsiloxane to the reactor and stir for 30 min under nitrogen protection. The reaction system was heated to 72°C, and 0.18 parts by weight of a platinum-based addition catalyst were added. The reaction was carried out at 72–78°C for 2.5 h. After the addition reaction is complete, the reaction system is heated to 88℃ and subjected to reduced pressure treatment at -0.090 to -0.096 MPa for 1.5 h. The reaction system was cooled to 65°C, and 36 parts by weight of vinyltrimethoxysilane were added. The reaction was carried out at 65-70°C for 2 hours. Add 0.12 parts by weight of triphenylphosphine, stir for 40 min, then treat under reduced pressure for 30 min at -0.085 to -0.092 MPa, cool and filter to obtain component A.

4. The silane-modified polysiloxane coating composition according to any one of claims 1 to 3, characterized in that, The coating composition is a homogeneous, single-component system before curing; In the single-component system, component A constitutes the main resin phase, components B and C serve as reactive silane components, and component D serves as a condensation catalyst, which is uniformly mixed in the single-component system.

5. The silane-modified polysiloxane coating composition according to claim 4, characterized in that, During the room temperature moisture curing process of the coating composition, ambient moisture causes the hydrolyzable alkoxysilane end groups of component A, the ethoxysilane groups of component B, and the methoxysilane groups of component C to hydrolyze and generate silanol groups. In this process, component D catalyzes the condensation reaction between silanol groups and between silanol groups and alkoxysilane groups that have not yet been hydrolyzed, forming a siloxane crosslinking structure with polysiloxane segments of component A as the main backbone and at least a portion of component B and at least a portion of component C participating in it.

6. The silane-modified polysiloxane coating composition according to claim 5, characterized in that, During the room temperature moisture curing process, at least a portion of the amino groups in component B undergoes a ring-opening reaction with the epoxy groups in component C, forming a linkage structure containing a β-hydroxyamine structure between component B and component C. The connecting structure and the siloxane crosslinking structure coexist in the cured coating.

7. A method for preparing a silane-modified polysiloxane coating composition as described in any one of claims 1 to 6, characterized in that, The coating composition is prepared according to the following method: After the preparation of component A is completed, component A is added to a dry stirring container under moisture-proof conditions. Under stirring, components B, C and D are added in sequence and mixed evenly to obtain a silane-modified polysiloxane coating composition that is in a uniform single-component state before curing.

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