Stable-structure Karst catalyst for synthesis of silane modified polyether

Abstract

The invention relates to the field of Karstedt catalysts, and discloses a stable-structure Karstedt catalyst for silane modified polyether synthesis, and the stable-structure Karstedt catalyst is prepared from the following raw materials in parts by weight: 2-4 parts of a Karstedt catalyst, 5-8 parts of a polyether siloxane block copolymer, 1-3 parts of nano silicon dioxide, 0.5-1.5 parts of triphenylphosphine, 20-25 parts of propylene glycol monomethyl ether and 0.5-1.0 part of an organosiloxane coupling agent. A polyether siloxane block copolymer is introduced into a Karstedt Catalyst system, and a flexible coating layer is formed outside a catalytic center by utilizing molecular compatibility of a silicon-oxygen chain segment of the polyether siloxane block copolymer and a platinum ligand, so that the exposure degree of the platinum center is remarkably reduced, interference of moisture and polar impurities in air is effectively inhibited, and the catalytic activity of the catalyst is improved. Therefore, the oxidation resistance and the storage stability of the catalyst are improved.

Description

Technical Field

[0001] This invention relates to the field of caster catalyst technology, specifically to a stable structural caster catalyst for the synthesis of silane-modified polyethers. Background Technology

[0002] Castrol catalyst is a platinum complex centered on platinum and formed by a divinyltetramethyldisiloxane ligand, with the chemical formula: Castella catalysts typically exist as pale yellow liquids with an active platinum content of approximately 20% or higher. They exhibit extremely high hydrosilylation activity in organosilicon chemistry and are widely used in the synthesis of silane-modified polyethers, silicone rubbers, silane-crosslinked polyethylene, and organosilicon elastomers. Through the action of castella catalysts, Si-H and C=C groups can undergo efficient addition under mild conditions, thereby achieving silane end-group modification of polymer molecular chains. However, castella catalysts are highly sensitive to moisture, oxygen, and polar impurities, and are prone to platinum center decoupling, oxidation, or aggregation during storage or use, leading to decreased catalytic activity or even deactivation.

[0003] In existing technologies, to improve the stability of cassiterite catalysts, modifications such as organophosphorus compounds, silicon-containing ligands, or resin loading are commonly employed. For example, triphenylphosphine is added to form Pt–P auxiliary coordination bonds to inhibit platinum oxidation, or the catalyst is loaded onto supports such as silica or porous resins to delay deactivation. However, these methods still have significant shortcomings: on the one hand, single ligand modification often only provides electronic effect regulation and is difficult to prevent platinum clustering; on the other hand, physical loading methods are prone to uneven distribution of active sites or support detachment; furthermore, there is a lack of effective interfacial bridging structures between organophosphorus compounds and siloxanes, resulting in limited system stability. Therefore, existing cassiterite catalysts are still prone to precipitation, discoloration, and activity decay after long-term storage or repeated use, limiting their application in the synthesis of silane-modified polyethers. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a stable cassiterite catalyst for the synthesis of silane-modified polyethers, thus solving the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a stable Karstedt catalyst for the synthesis of silane-modified polyethers, comprising the following raw materials in parts by weight: 2-4 parts of Karstedt catalyst, 5-8 parts of polyether siloxane block copolymer, 1-3 parts of nano silica, 0.5-1.5 parts of triphenylphosphine, 20-25 parts of propylene glycol methyl ether, and 0.5-1.0 parts of organosiloxane coupling agent.

[0006] Preferably, the chemical formula of the Karstedt catalyst is as follows: It contains ≥20% active platinum and is a pale yellow liquid.

[0007] Preferably, the polyether siloxane block copolymer is an organophilic phase protectant that forms a spatial encapsulation structure with platinum ligands at the molecular level.

[0008] Preferably, the surface of the nano-silica is silanized, which enables it to form hydrogen bonds with organosiloxane segments, thereby improving the uniformity of dispersion.

[0009] Preferably, a method for preparing a stable cassiterite catalyst for the synthesis of silane-modified polyethers includes the following steps: S1. The reaction vessel shall be constructed under an inert gas protective environment with an oxygen content ≤0.5%; S2. Add nano-silica to propylene glycol methyl ether and disperse to obtain a stable dispersion; S3. Prepare a triphenylphosphine solution to form an auxiliary ligand complex solution; S4. Slowly add the cassiterite catalyst to the dispersion and add an auxiliary ligand complexing solution to allow the platinum center to form a coordination complex with the phosphine group; S5. Add KH-550 to the mixed system to form an organic-inorganic interface bridge; S6. The system is matured and stabilized to obtain a uniform and transparent stable cassiterite catalyst.

[0010] Preferably, in step S1, after sealing the reactor, nitrogen gas with a purity of ≥99.9% is introduced from the bottom for 5-8 minutes, maintaining a slight positive pressure of 0.01-0.02 MPa and an oxygen content of ≤0.5%.

[0011] Preferably, in step S2, 1-3 parts of nano-silica are added to 10-15 parts of propylene glycol methyl ether, and intermittent stirring is used, with stirring for 5 minutes and stopping for 1 minute, for a total stirring time of 30-40 minutes, at a speed of 800-1000 r / min, so that the nano-silica... They are scattered and do not come together.

[0012] Preferably, in step S3, 0.5-1.5 parts of triphenylphosphine are added to 10 parts of propylene glycol methyl ether, the temperature is raised to 40-45°C, and the mixture is stirred at 600-800 r / min for 20 min until it is completely dissolved and forms a clear liquid.

[0013] Preferably, the ripening temperature in step S6 is 25-30℃, the time is 1-2 hours, and the oxygen content is ≤0.5%. This invention provides a stable cassiterite catalyst for the synthesis of silane-modified polyethers. It possesses the following beneficial effects: 1. This invention introduces a polyether siloxane block copolymer into the Karstedt Catalyst system. By utilizing the molecular-level compatibility between its siloxane segments and platinum ligands, a flexible coating layer is formed outside the catalytic center, which significantly reduces the exposure of the platinum center and effectively suppresses the interference of moisture and polar impurities in the air, thereby improving the catalyst's antioxidant capacity and storage stability.

[0014] 2. This invention utilizes surface-silanized nano-silica as a dispersant and anti-agglomeration stabilizer. By forming hydrogen bonds with organosiloxane segments, it constructs a composite structure of "inorganic framework-organic coating", thereby achieving uniform dispersion and anti-agglomeration of the cassiterite catalyst and keeping the catalytic activity stable during long-term storage and use.

[0015] 3. This invention further utilizes an organosiloxane coupling agent to initiate an interfacial condensation reaction in the system. The amino group of the coupling agent forms a weak hydrogen bond complex with the organophosphine ligand, and the siloxane end group forms a Si–O–Si bond with the surface of nano-silica. This creates a stable "organic-inorganic interface bridge" between the organic and inorganic phases, effectively preventing the precipitation and migration of platinum complexes. This results in a more complete and stable overall catalyst structure, and exhibits higher reaction selectivity and reusability in the synthesis of silane-modified polyethers. Attached Figure Description

[0016] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0018] Example: Please see the appendix Figure 1 This invention provides a stable structural cassiterite catalyst for the synthesis of silane-modified polyethers, comprising the following raw materials in parts by weight: Karstedt catalyst, as the active ingredient: 2-4 parts; its chemical formula is... With a molecular weight of 381.48 and CAS number 68478-92-2, it is a pale yellow liquid with an active platinum content of ≥20%. As the main catalytic center, its Pt atoms form coordination complexes with Si-H and C=C groups, exhibiting extremely high activity in hydrosilylation reactions. However, this complex is sensitive to moisture and polar impurities, which can easily lead to decoupling or precipitation of the platinum center and deactivation. Polyether siloxane block copolymer, an organophilic phase protectant: 5-8 parts; its siloxane segments are compatible with platinum ligands and can form a spatial encapsulation structure at the molecular level, reducing the exposure of the platinum center and thus inhibiting the interference of moisture or impurities in the air; Nano-silica, as a physical dispersant and anti-aggregation stabilizer: 1-3 parts; its surface hydroxyl groups are silanized and then form hydrogen bonds with organosiloxane segments, which improves the dispersion uniformity of the catalyst in organic solvents and prevents platinum clustering; Organophosphorus ligands, including triphenylphosphine: 0.5-1.5 parts; used to enhance the electron cloud density of platinum centers, form auxiliary ligands, inhibit platinum atom oxidation, and improve the storage stability of the catalyst; Propylene glycol methyl ether: 20-25 parts; as a solvent and dispersion medium, it has moderate polarity and is compatible with organosiloxane and organophosphine systems, ensuring system homogeneity; Organosiloxane coupling agents, such as KH-550: 0.5-1.0 parts; form weak hydrogen bond complexes with amino groups and phosphine ligands, while the siloxane ends interact with nano-... Surface condensation constructs an "organic-inorganic bridge," enhancing the overall system structure and resistance to exudation. Inert gas (nitrogen or argon): used for oxidation protection; to maintain the oxygen content in the reaction system ≤0.5% and prevent the platinum complex from decomposing into Pt black or inactive oxides.

[0019] A method for preparing a stable structural cassiterite catalyst for the synthesis of silane-modified polyethers S1. Establishment of an inert gas protective environment In a reactor equipped with a nitrogen inlet and oxygen content monitoring device, first check the sealing performance and confirm that there is no leakage. Then, introduce nitrogen with a purity of ≥99.9% from the bottom and maintain it for 5-8 minutes. Detect the oxygen content in the reactor using an oxygen sensor to ensure it is ≤0.5%. At the same time, maintain a slight positive pressure (0.01-0.02MPa) to remove air and water vapor and build an inert system.

[0020] This step lays the foundation for the subsequent introduction of the Karstedt catalyst, preventing the platinum center from being oxidized to Pt. 0 Alternatively, PtO_x can be used to ensure that the active centers of the catalyst are in a stable valence state.

[0021] S2. Preparation of nano-silica dispersion Under the aforementioned inert environment, add 1-3 parts by weight of surface-silanized nano-silica to 10-15 parts by weight of propylene glycol methyl ether, start the stirring device, control the speed at 800-1000 r / min, and continue stirring for 30-40 min. To prevent excessive shearing... Agglomeration can be achieved by intermittent stirring (stirring for 5 minutes, stopping for 1 minute, and circulating), while maintaining nitrogen gas flow to keep the oxygen content ≤0.5%. After thorough dispersion, a stable nano-SiO2 dispersion is obtained.

[0022] This dispersion will serve as a support phase in subsequent steps to carry the organic phase ligands and the Karstedt catalyst, thereby forming a multiphase stable framework.

[0023] S3. Preparation of auxiliary ligand complexing solution In a separate reaction vessel equipped with the same inert protective device, add 0.5-1.5 parts triphenylphosphine to 10 parts propylene glycol methyl ether, heat to 40-45℃, maintain a stirring speed of 600-800 r / min, and stir for 20 min until completely dissolved, forming a homogeneous and clear solution. The triphenylphosphine solution can act as an electron-rich aggregate, forming weak coordination bonds (Pt–P bonds) with platinum atoms during subsequent compounding processes. This increases the electron cloud density of the platinum centers, reducing their reactivity with polar molecules such as water and alcohols, thus laying the foundation for subsequent chemical stabilization.

[0024] S4. Introduction and in-situ coordination of the main catalyst Maintain an inert gas atmosphere in the S2 step system, with an oxygen content ≤0.5%. Control the reaction temperature at 25-30℃, adjust the stirring speed to 500-700 r / min, and slowly add 2-4 parts of Karstedt catalyst to nanometer size. In the dispersion, the dropping rate was controlled at 0.2 mL / min to prevent phase separation caused by excessively high local concentrations. After the addition was complete, stirring was continued for 15 min to ensure uniform dispersion. Then, the triphenylphosphine solution obtained from S3 was slowly added while stirring and monitoring the color change of the system. It should remain pale yellow and transparent. Stirring was continued for 20 min to allow the platinum center and phosphine group to form a stable coordination complex structure.

[0025] This step enables the formation of a "dispersed framework + electronically stable dual structure," which allows the Karstedt catalyst to be dual-coated with organic ligands and inorganic supports, significantly improving its stability.

[0026] S5. Interfacial strengthening reaction of organosiloxane coupling agents In the mixing system of step S4, the temperature is maintained at 25-30℃, the stirring speed at 600 r / min, and the oxygen content is ≤0.5%. 0.5-1.0 parts of KH-550 (γ-aminopropyltriethoxysilane) are added, and stirring is continued for 15-20 min. The amino group in KH-550 forms a weak hydrogen bond complex with the π-electrons of the benzene ring of triphenylphosphine, while its siloxane end group undergoes a condensation reaction with the hydroxyl groups on the surface of nano-SiO2 to generate Si–O–Si bonds. This forms an "organic-inorganic interface bridge" in the system, significantly improving the structural integrity and long-term dispersion stability of the catalyst. At this point, the system gradually transforms from a molecular-level coordination mechanism into a three-dimensional network composite structure.

[0027] S6. System maturation and stabilization The reactor was kept under a slight positive nitrogen pressure for 1-2 hours, with the temperature controlled at 25-30℃, and the oxygen content was monitored periodically (≤0.5%). During the maturation period, coordination and hydrogen bond rearrangement in the system gradually reached equilibrium, and triphenylphosphine formed a stable dynamic complex equilibrium with the Karstedt catalyst, while KH-550 and... The condensation reaction further stabilizes the structure and prevents component migration during storage. After aging, nitrogen gas is slowly released, and the mixture is cooled to room temperature to obtain a homogeneous, transparent, pale yellow, stable cassiterite catalyst.

[0028] The following is a specific example: Example 1: A stable cassiterite catalyst for the synthesis of silane-modified polyethers comprises the following raw materials in parts by weight: Karstedt catalyst: 2 parts Polyether siloxane block copolymer: 5 parts Nano silica (surface silanization treatment): 1 part Triphenylphosphine: 0.5 parts Propylene glycol methyl ether: 20 parts KH-550 coupling agent: 0.5 parts Prepared using steps S1 to S6.

[0029] Example 2: Karstedt catalyst: 4 parts Polyether siloxane block copolymer: 8 parts Nano silica (surface silanization treatment): 3 parts Triphenylphosphine: 1.5 parts Propylene glycol methyl ether: 25 parts KH-550 coupling agent: 1 part Prepared using steps S1 to S6 To verify the actual effectiveness of this invention, the following comparative examples are prepared: Comparative Example 1: Raw material composition (parts by weight): Karstedt catalyst: 2 parts Polyether siloxane block copolymer: 5 parts (lower limit than the example). Nano silica (surface silanization treatment): 1 part Triphenylphosphine: 0.5 parts Propylene glycol methyl ether: 20 parts KH-550 coupling agent: omitted Inert gas (nitrogen): Maintain oxygen content ≤0.5% as needed. The preparation method is basically the same as in Example 1, but the KH-550 coupling agent is omitted in the interface strengthening step, while the other steps remain the same, including the dispersion of nano-SiO2, the compounding of auxiliary ligands and the addition of Karstedt catalyst.

[0030] Comparative Example 2: Raw material composition (parts by weight): Karstedt catalyst: 2 parts Polyether siloxane block copolymer: 5 parts Nano-silica: 1 part (unsilanized) Triphenylphosphine: 0.5 parts Propylene glycol methyl ether: 20 parts KH-550 coupling agent: 0.5 parts Inert gas (nitrogen): Maintain oxygen content ≤0.5% as needed. The preparation method is similar to that in Example 1, but the nano-silica was not subjected to surface silanization treatment. The remaining steps are the same.

[0031] Comparative Example 3: Raw material composition (parts by weight): Karstedt catalyst: 2 parts Polyether siloxane block copolymer: 5 parts Nano silica (surface silanization treatment): 1 part Triphenylphosphine: 0.25 parts (half the dose) Propylene glycol methyl ether: 20 parts KH-550 coupling agent: 0.5 parts Inert gas (nitrogen): Maintain oxygen content ≤0.5% as needed. The preparation method remains the same as in Example 1, but the amount of the auxiliary ligand triphenylphosphine is halved. All other steps remain unchanged.

[0032] Comparative Example 4: Raw material composition (parts by weight): Karstedt catalyst: 2 parts Polyether siloxane block copolymer: 5 parts Nano silica (surface silanization treatment): 1 part Triphenylphosphine: 0.5 parts Propylene glycol methyl ether: 20 parts KH-550 coupling agent: 0.5 parts Inert gas protection omitted The preparation method is basically the same as in Example 1, but the operation is carried out in air without nitrogen protection.

[0033] Comparative Example 5: Use commercially available Karstedt Catalyst and commercial tin-based catalyst DBTDL-Standard directly; To verify the properties of the stable cassiterite catalyst for the synthesis of silane-modified polyethers provided by this invention, the following experiment was designed: I. Experimental Objective By comparing the examples and comparative examples, the activity, long-term stability and dispersion uniformity of the stable structure cassiterite catalyst prepared in this invention in the hydrosilylation reaction are verified.

[0034] II. Experimental Materials Catalysts prepared in Examples 1 and 2 Comparative Examples 1 to 5 Catalysts Silane-modified polyether substrate (H-PEG-SiH, national standard requires purity ≥98%) Organic solvent: toluene Nitrogen (purity ≥ 99.9%) III. Experimental Instruments Glass reactor (with stirring, temperature control, and nitrogen protection) Fourier Transmission Infrared Spectrometer (FT-IR) Nuclear magnetic resonance (¹H-NMR) Viscometer (Brookfield type) Laser particle size analyzer (for dispersion testing) Incubator (for storage stability testing) IV. Experimental Methods 1. Catalytic activity determination Add 10 g of silane-modified polyether substrate to 100 mL of toluene and purge with nitrogen for protection. Add 0.5 wt% catalyst (based on the weight of polyether) Reaction temperature: 80℃, stirring at 500 rpm Reaction time: Real-time monitoring and recording of the time required for the reaction to complete (disappearance of the hydroxyl group absorption peak, FT-IR detection), recording of reaction yield and reaction time, catalytic efficiency = (conversion rate / reaction time) 2. Dispersion and Uniformity Test The prepared catalyst was added to toluene and diluted to 10 wt%. The particle size distribution was determined using a laser particle size analyzer. The uniformity evaluation indicators were: particle size D50 and multipeak rate. The smaller the D50 and the more uniform the single peak, the better the dispersibility. 3. Long-term stability testing The catalyst was stored in a sealed container at 25°C and 60% relative humidity. Samples were taken periodically (at 0, 15, 30, and 60 days) to determine the activity retention rate (using the hydrosilylation rate). Color changes and precipitation were also observed. 4. Evaluation of Interface Strengthening Effect: Comparison of Catalysts Containing KH-550 and Catalysts Omitting KH-550; Measurement of Particle Size and Reaction Rate; Evaluation of the Influence of Organic-Inorganic Bridges on Stability. V. Experimental Data Catalytic activity experiment

[0035] Experimental conclusions: The catalysts in Examples 1 and 2 exhibited the highest activity, with a conversion rate ≥99%, and their reaction times were significantly shorter than those of the comparative example, indicating that the stable structural design of this invention effectively improved catalytic efficiency. The comparative example catalyst showed a significant decrease in activity due to the lack of an organic-inorganic interface or auxiliary ligand protection. Commercially available catalysts showed moderate performance, but their stability was inferior to that of the examples.

[0036] Dispersion experiment

[0037] Experimental conclusions: The catalysts in the examples exhibited excellent dispersibility, with uniform and stable particle size, indicating that the nano-SiO2 dispersion framework and the organic-inorganic interface bridge effectively inhibited platinum clustering. The comparative examples, lacking surface treatment or interface protection, showed increased particle size and multiple peaks, making them prone to precipitation.

[0038] Long-term stability test

[0039] Experimental conclusion: The catalyst in the example maintained extremely high activity and no precipitation under long-term storage conditions, proving that the stable structure can effectively prevent platinum decoordination and agglomeration. The comparative catalyst and commercially available catalysts showed significantly insufficient stability.

[0040] Interface enhancement effect experiment

[0041] Experimental conclusion: The organic-inorganic interface bridge (KH-550) significantly improves the dispersion uniformity and activity of the catalyst, proving that the interface strengthening effect is indispensable in stabilizing catalysts.

[0042] By introducing polyether siloxane block copolymers as organophilic phase protectants, nano-silica as a dispersing and anti-aggregation framework, and organophosphine ligands as electronically stabilizing centers, and supplemented with organosiloxane coupling agents to form an "organic-inorganic interface bridge," the structural stability and antioxidant properties of the system can be significantly improved while maintaining catalytic activity. This meets the requirements for long-term high efficiency and stable reaction of catalysts in the synthesis of silane-modified polyethers. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A stable structural cassiterite catalyst for the synthesis of silane-modified polyethers, characterized in that: The raw materials include the following parts by weight: 2-4 parts Karstedt catalyst, 5-8 parts polyether siloxane block copolymer, 1-3 parts nano silica, 0.5-1.5 parts triphenylphosphine, 20-25 parts propylene glycol methyl ether, and 0.5-1.0 parts organosiloxane coupling agent.

2. The stable structural cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 1, characterized in that: The chemical formula of the Karstedt catalyst is as follows: It contains ≥20% active platinum and is a pale yellow liquid.

3. The stable structural cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 1, characterized in that: The polyether siloxane block copolymer is an organophilic phase protectant that forms a spatial encapsulation structure with platinum ligands at the molecular level.

4. The stable cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 1, characterized in that: The surface of the nano-silica is silanized, which enables it to form hydrogen bonds with organosiloxane segments, thereby improving the uniformity of dispersion.

5. A method for preparing a stable structural cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 1, 2, 3, or 4, characterized in that: Includes the following steps: S1. The reaction vessel shall be constructed under an inert gas protective environment with an oxygen content ≤0.5%; S2. Add nano-silica to propylene glycol methyl ether and disperse to obtain a stable dispersion; S3. Prepare a triphenylphosphine solution to form an auxiliary ligand complex solution; S4. Slowly add the cassiterite catalyst to the dispersion and add an auxiliary ligand complexing solution to allow the platinum center to form a coordination complex with the phosphine group; S5. Add KH-550 to the mixed system to form an organic-inorganic interface bridge; S6. The system is matured and stabilized to obtain a uniform and transparent stable cassiterite catalyst.

6. The method for preparing a stable structural cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 5, characterized in that: In step S1, after sealing the reactor, nitrogen gas with a purity of ≥99.9% is introduced from the bottom for 5-8 minutes, maintaining a slight positive pressure of 0.01-0.02 MPa and an oxygen content of ≤0.5%.

7. The method for preparing a stable structural cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 5, characterized in that: In step S2, 1-3 parts of nano-silica are added to 10-15 parts of propylene glycol methyl ether, and intermittent stirring is used, with stirring for 5 minutes and stopping for 1 minute, for a total stirring time of 30-40 minutes at a speed of 800-1000 r / min, so that the nano-silica... They are fully dispersed and do not cluster together.

8. The method for preparing a stable structural cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 5, characterized in that: In step S3, 0.5-1.5 parts of triphenylphosphine are added to 10 parts of propylene glycol methyl ether, the temperature is raised to 40-45°C, and the mixture is stirred at 600-800 r / min for 20 min until it is completely dissolved and forms a clear liquid.

9. The method for preparing a stable structural cassiterite catalyst for the synthesis of silane-modified polyethers according to claim 5, characterized in that: The S6 step involves a curing temperature of 25-30℃, a curing time of 1-2 hours, and an oxygen content of ≤0.5%.

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