High temperature and high humidity resistant polyisocyanate composition and method of making

Abstract

The application discloses a high-temperature and high-humidity resistant polyisocyanate composition and a preparation method thereof. The polyisocyanate composition comprises a silicon-based isocyanurate mononuclear structure formed by aliphatic diisocyanate and alkoxy silane monoisocyanate. The isocyanate composition has the advantages of no solvent addition, low viscosity, excellent stability in a high-temperature and high-humidity environment, simple manufacturing process, and the like, and is particularly suitable for fields with complex and changeable use environments and long service life, such as the automobile industry coating and adhesive fields.

Description

Technical Field

[0001] This invention belongs to the field of isocyanates, and particularly relates to a high-temperature and high-humidity resistant polyisocyanate composition and its preparation method. Background Technology

[0002] Polyurethane resin is a general term for macromolecular compounds containing repeating urethane groups in their main chain. It can be widely used in coatings, adhesives, sealants, elastomers, foams, and reinforced composite materials. Especially in automotive coatings and structural adhesives, polyurethane products are expected to possess high mechanical strength, strong adhesion to substrates, and excellent weather resistance. While ordinary polyurethane has good mechanical properties and excellent abrasion resistance, it often requires a primer for bonding and adhesion, and is prone to foaming and delamination failure, particularly in high-temperature and high-humidity environments.

[0003] In recent years, some studies have attempted to modify polyurethane products with silicone-based resins, but many problems still need to be solved.

[0004] The technical solution of CN105482758A uses an NCO-terminated polyurethane prepolymer to react with phenylaminomethyltriethoxysilane to obtain a silane-terminated polymer. However, this technical solution has the following drawbacks: the reaction rate is slow, and the steric hindrance effect of the benzene ring will result in incomplete end-capping, which will affect the final performance of the product. In addition, its high viscosity will affect the wetting of the substrate interface and will not prevent it from being damaged by moisture.

[0005] CN117384579A uses mercaptopropyltrimethoxysilane and hydroxyethyl methacrylate to react with azobisisobutyronitrile (AIB) to obtain a modified silane coupling agent. This agent is then reacted with a polyurethane prepolymer until the product is free of NCO groups. This product can introduce organosilane structures into polyurethane through chemical bonds via reactive groups, thereby improving the tensile strength and elongation at break of the product. However, this process is complex, and since all NCO groups are reacted, it is difficult to achieve further thermal or wet crosslinking reactions, making it unsuitable for long-term use in high-temperature and high-humidity environments.

[0006] In summary, there is an urgent need for a solvent-free, low-viscosity polyisocyanate composition containing siloxanes with excellent overall mechanical properties. Summary of the Invention

[0007] One objective of this invention is to provide a polyisocyanate composition containing siloxane alkyl groups. This composition has the advantages of being solvent-free and having low viscosity, and can significantly improve construction efficiency and the overall mechanical properties of the product. In particular, it has been found that products prepared from this composition exhibit excellent performance stability under high temperature and high humidity environments.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A polyisocyanate composition containing siloxane, the polyisocyanate composition comprising a silyl isocyanurate mononuclear structure formed from an aliphatic diisocyanate and an alkoxysilane monoisocyanate, as shown in Formula I:

[0010]

[0011] Wherein, R1 is the residual group of an aliphatic diisocyanate after removing the isocyanate group, R2 is an alkyl group with carbon number between C1 and C8, and R3, R4, and R5 are each independently an alkyl or alkoxy group with carbon number between C1 and C4, and at least one of R3, R4, and R5 is an alkoxy group, preferably two or three of R3, R4, and R5 are alkoxy groups.

[0012] Aliphatic isocyanates possess excellent weather resistance and anti-yellowing properties. Polyisocyanurates polymerized from them have monocyclic or polycyclic structures. The six-membered ring structure of these isocyanurates is stable and exhibits excellent chemical resistance and mechanical properties. The inventors discovered that copolymerizing alkoxysilane monoisocyanates with aliphatic diisocyanates allows for the introduction of alkoxysilanes via chemical bonds without affecting the six-membered ring structure. This effectively prevents migration from the resin matrix, resulting in a system with stronger adhesion than that achieved by introducing traditional small-molecule monosiloxane structures. This further improves the isocyanate composition and makes it suitable for various applications.

[0013] In one embodiment of the present invention, the polyisocyanate composition comprises an aliphatic diisocyanate oligomer, a silyl isocyanurate mononuclear monomer, a free aliphatic diisocyanate monomer, and a free alkoxysilane monoisocyanate; preferably, the mass fraction of the silyl isocyanurate mononuclear monomer in the polyisocyanate composition is 1-30% based on the total mass of the composition; preferably, the sum of the contents of the free aliphatic diisocyanate monomer and the free alkoxysilane monoisocyanate is less than 1.0%.

[0014] In one embodiment of the present invention, the aliphatic diisocyanate is selected from C4-C atoms containing two terminal isocyanate groups, wherein the isocyanate groups are not directly connected to the benzene ring. 30 Diisocyanate, preferably one or more of pentamethylene diisocyanate, hexamethylene diisocyanate, phenyl diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate, more preferably one or more of hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate.

[0015] In one embodiment of the present invention, the alkoxysilane monoisocyanate is selected from C1-C64S alkoxysilanes containing terminal isocyanate groups. 10 The alkoxysilane is preferably one or more of the following monoisocyanates: propylmethyldiethoxysilane, propylmethyldimethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butylmethyldimethoxysilane, butylmethyldiethoxysilane, and butyltriethoxysilane; more preferably, propyltrimethoxysilane and / or propyltriethoxysilane.

[0016] Another object of the present invention is to provide a method for preparing a polyisocyanate composition containing siloxane.

[0017] A method for preparing a polyisocyanate composition containing siloxane, wherein the composition is the above-mentioned polyisocyanate composition, and the preparation method comprises the following steps:

[0018] Aliphatic diisocyanate and alkoxysilane monoisocyanate react under catalytic conditions, the reaction is terminated, and a solution of isocyanate mixture is obtained. Unreacted aliphatic diisocyanate and alkoxysilane monoisocyanate are removed to obtain the target polyisocyanate composition.

[0019] In one embodiment of the present invention, the reaction temperature is 50-150°C, preferably 100-135°C.

[0020] In one embodiment of the present invention, the catalyst is one or more of a halogenated quaternary phosphonium salt, a halogenated spirocyclic ammonium salt, and a metal alkoxide, preferably one or more of 5-aza-spiro[4.5]decane difluoride, zirconium tetrapentoxide, (2-hydroxyethyl)triphenylphosphonium chloride, and tetrabutylphosphonium difluoride; preferably, the amount of catalyst added is 50-2000 ppm based on the total mass of aliphatic diisocyanate and alkoxysilane monoisocyanate, more preferably 100-1000 ppm. The catalyst can catalyze the self-polymerization of aliphatic diisocyanate monomers to form oligomers, and can also catalyze the hybrid polymerization of aliphatic diisocyanate and alkoxysilanes with terminal isocyanate groups, but has no significant catalytic effect on the polymerization of alkoxysilanes with terminal isocyanate groups themselves.

[0021] In one embodiment of the present invention, the termination reaction is achieved by adding a terminator; preferably, the reaction is terminated when the polymerization conversion of the aliphatic diisocyanate reaches 35-65%, more preferably 40-50%.

[0022] Another object of the present invention is to provide the use of a polyisocyanate composition containing siloxane.

[0023] Use of a polyisocyanate composition containing siloxane, said composition being the polyisocyanate composition described above, or a composition prepared by the method described above, said composition being used in coatings or adhesives, preferably in automotive coatings or adhesives, more preferably in polyurethane automotive sealants.

[0024] Another object of the present invention is to provide a polyurethane automotive sealant.

[0025] A polyurethane automotive sealant, wherein the sealant uses the above-described polyisocyanate composition or a composition prepared by the above-described preparation method, and the sealant uses a polyisocyanate composition containing siloxane as a curing agent.

[0026] Methods for preparing automotive polyurethane sealants from isocyanate compositions are well known in the art. For example, the present invention preferably employs the following method to prepare a polyurethane sealant from an isocyanate composition: At 15-50°C and relative humidity below 35%, 40-80 parts of trifunctional polyether polyol A with a molecular weight of 1000-6000 Daltons, 10-40 parts of difunctional polyether polyol B with a molecular weight of 500-3000 Daltons, and 10-20 parts of carbon black filler are added to an adhesive preparation apparatus, along with 0.01-1% of any additives based on the total mass of polyether polyols A and B and the carbon black filler. After mechanically mixing 200-1500 ppm of urethane catalyst, add the isocyanate composition containing siloxane at an NCO / OH ratio of 1.0-1.05. Mechanically stir for 2-5 minutes to ensure uniform mixing. Remove air bubbles by vacuuming at room temperature, then pour the mixture into a standard mold. The mold can be made with glass or plastic substrate, depending on the situation. After pouring, cure at 80℃-120℃ for 0.5-3 hours, and then cure at room temperature for 12-48 hours to finally obtain polyurethane sealant resin samples.

[0027] For example, the polyether polyol is selected from at least one of polypropylene oxide ether polyol, polyethylene oxide ether polyol, and polypropylene oxide-ethylene oxide ether copolyol, preferably selected from at least one of polypropylene oxide ether polyol and polypropylene oxide-ethylene oxide ether polyol, and more preferably selected from polypropylene oxide ether polyol.

[0028] For example, the initiator of the difunctional polyether polyol is a diol, such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, trimethylpentanediol, cyclohexanediol, 1,5-pentanediol, or 1,6-hexanediol. The initiator of the trifunctional polyether polyol is a triol, such as trimethylolpropane, ethoxylated trimethylolpropane, or glycerol.

[0029] For example, the additive can be one or a mixture of any of the following additives: defoamer, wetting agent, dispersant, leveling agent, silane coupling agent, etc.

[0030] Compared with the prior art, the advantages of this invention are as follows:

[0031] The composition of this invention not only ensures that the product has the advantages of being solvent-free and having low viscosity, but also significantly improves the construction efficiency and the overall mechanical properties of the product. In particular, it has been found that the product prepared by this composition has excellent performance stability under high temperature and high humidity environments, and is therefore particularly suitable for polyurethane sealants or automotive clear coats. Detailed Implementation

[0032] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0033] The main raw materials and their sources in the following embodiments and comparative examples of this invention are as follows:

[0034] Isophorone diisocyanate (IPDI), Wanhua Chemical Group Co., Ltd.

[0035] Hexamethylene diisocyanate (HDI), Wanhua Chemical Group Co., Ltd.

[0036] 3-Isocyanate propyltrimethoxysilane, purchased from Huai'an Hongtu New Materials Co., Ltd.;

[0037] 3-Isocyanate propyltriethoxysilane, purchased from Huai'an Hongtu New Materials Co., Ltd.;

[0038] 3-Isocyanate butylmethyldimethoxysilane, purchased from Huai'an Hongtu New Materials Co., Ltd.;

[0039] Zirconium tetrapentyl alcohol, a metal alkoxide catalyst, was purchased from Jianrui New Materials Co., Ltd.

[0040] 5-Nazonium-spiro[4.5]decane difluoride, a halogenated spirocyclic catalyst, was purchased from Aladdin Chemical Reagent Co., Ltd.

[0041] Dioctyl phosphate, a terminator, was purchased from Hangzhou Qianyang Technology Co., Ltd.

[0042] T12, dibutyltin dilaurate, is a commonly used urethane catalyst for polyurethane resins, purchased from Nanjing Aidewang Co., Ltd.

[0043] Wanol F3135 is a polyether polyol commonly used in polyurethane sealants. It has an average functionality of 3 and a molecular weight of approximately 5000 g / mol. It is used as a reactive resin in isocyanate compositions for polyurethane sealants and is sourced from Wanhua Chemical Group Co., Ltd.

[0044] Puranol D220, a polyether polyol commonly used in polyurethane sealants, has an average functionality of 2 and a molecular weight of approximately 2000 g / mol. It is used as a reactive resin in isocyanate compositions for polyurethane sealants and was purchased from Jiahe Chemical Co., Ltd.

[0045] AD-4810, a composite additive for polyurethane sealants, was purchased from Guangzhou Honghai New Material Technology Co., Ltd.

[0046] Unless otherwise specified, all contents in this invention refer to mass content.

[0047] (1) The NCO content test shall be performed in accordance with standard GB / T 12009.4;

[0048] (2) Viscosity testing shall be performed according to the dynamic viscosity at 25°C using a slab viscometer (Brookfield DT-2);

[0049] (3) The method for analyzing the mononuclear structure of silicon-based isocyanurate is as follows:

[0050] Using an AVANCE 600 FT-NMR spectrometer manufactured by Bruker, with deuterated chloroform (CDCl3) as the solvent, and at a sample concentration of 5% (mass concentration of the prepared isocyanurate product), the NMR was performed at 600 MHz for 48 hours. 13 Qualitative analysis was performed using C10 NMR spectroscopy. For example, the characteristic shifts of the C10 NMR spectroscopy of the six-membered ring structure of silane-based isocyanurate, as shown in Structure I prepared based on hexamethylene diisocyanate and 3-isocyanate propyltrimethoxysilane, were δ137.6 ppm, δ152.7 ppm, and δ155.8 ppm, respectively.

[0051] (4) The mass fraction test method for the mononuclear structure (I) of silicone isocyanurate is as follows: The terminal isocyanate group in the polyisocyanate composition is derivatized with methanol and analyzed by liquid chromatography-mass spectrometry (LC / MS). The preparation and test method are as follows:

[0052] (a) Sample preparation method: Weigh a quantitative amount of polyisocyanate composition and dilute it with an excess of stoichiometric methanol. Allow the mixture to stand for three days to allow the existing isocyanate groups to react completely with the methanol, thereby preparing a methanol-derived solution.

[0053] (b) Measurement method:

[0054] The methanol-derived solution obtained above was measured using the following apparatus.

[0055] Agilent LC (Liquid Chromatograph), Agilent 1100 series

[0056] Column: Phenomenex, Kinetex 2.6μXB-C18 100A (inner diameter 2.1mm, length 50mm)

[0057] Column temperature: 40℃

[0058] Detection: 205nm

[0059] Flow rate: 0.35 mL / mins

[0060] Mobile phase: a gradient between solutions A and B, where A = water (0.05% formic acid) and B = methanol.

[0061] Injection volume: 2μL

[0062] Thermo MS (mass spectrometer)

[0063] Device: Thermo Electron, LCQ

[0064] Ionization: APCI

[0065] Mode: Positive ion

[0066] Scan range: m / z 150~2000

[0067] The mass fraction is determined by the integral area of ​​the methanol adduct of structure (I).

[0068] (5) The sum of the contents of free aliphatic diisocyanate monomers and alkoxysilane monoisocyanates was tested using high performance liquid chromatography (HPLC) to establish an external standard curve. The key parameters are as follows:

[0069] Column: Waters XSelect HSS T3 5um 4.6*250mm;

[0070] Automated Sampler: SIL-20A

[0071] Column temperature: 40℃

[0072] Injection volume: 10 μL

[0073] Detection wavelength: 281nm

[0074] Derivatizing reagent: 4% 1-methoxyphenylpiperazine-acetonitrile solution.

[0075] The concentrations of the free aliphatic diisocyanate monomer and alkoxysilane monoisocyanate were determined based on their respective peak areas and external standard curves. The sum of these two concentrations was then used as the total content of the free aliphatic diisocyanate monomer and alkoxysilane monoisocyanate monomer in the polyisocyanate composition.

[0076] Example 1

[0077] Under an inert gas atmosphere, 1000g of hexamethylene diisocyanate was first added to the reaction vessel and heated to 105℃. Then, 0.50g of 5-aza-spiro[4.5]decane hydrogen difluoride catalyst was added. Simultaneously, 3-isocyanate propyltrimethoxysilane was added dropwise using a continuous feeding method, and the polymerization reaction was carried out continuously under the action of the catalyst. The addition of 3-isocyanate propyltrimethoxysilane was controlled to a cumulative amount of 200g over 50 minutes, and then the dropwise addition was stopped. The reaction rate was maintained until the polymerization conversion of hexamethylene diisocyanate reached 65%. At that time, 0.25g of dioctyl phosphate terminator was added to terminate the reaction, resulting in an isocyanate mixture solution. Unreacted hexamethylene diisocyanate and 3-isocyanate propyltrimethoxysilane were further removed by distillation to obtain polyisocyanate composition 1#. After analysis, the NCO content of the polyisocyanate composition was 14.0%, the sum of the contents of free hexamethylene diisocyanate and 3-isocyanate propyltrimethoxysilane monomers was 0.51%, the viscosity was 2875cp / 25℃, and the content of mononuclear structure I was 15.3%.

[0078] Example 2

[0079] Under an inert gas atmosphere, 1000g of hexamethylene diisocyanate was first added to the reaction vessel and heated to 110°C. Then, 0.20g of 5-aza-spiro[4.5]decane hydrogen difluoride catalyst was added. Simultaneously, 3-isocyanate propyltrimethoxysilane was added dropwise using a continuous feeding method, and a continuous copolymerization reaction was carried out under the action of the catalyst. The continuous addition of 3-isocyanate propyltrimethoxysilane was controlled to 200g over 110 minutes and then stopped. The reaction rate was maintained until the polymerization conversion of hexamethylene diisocyanate reached 35%. At a certain percentage, 0.11 g of dioctyl phosphate terminator was added to terminate the reaction, yielding an isocyanate mixture solution. Unreacted hexamethylene diisocyanate and 3-isocyanate propyltrimethoxysilane were further removed by distillation to obtain polyisocyanate composition 2#. Analysis showed that the NCO content of the polyisocyanate composition was 18.1%, the sum of the contents of free hexamethylene diisocyanate and 3-isocyanate propyltrimethoxysilane monomers was 0.25%, the viscosity was 1839 cp / 25℃, and the mononuclear structure I content was 23.7%.

[0080] Example 3

[0081] Under an inert gas atmosphere, 1000g of hexamethylene diisocyanate was first added to the reaction vessel and heated to 105℃. Then, 0.25g of tetra-n-pentyl zirconium catalyst was added. Simultaneously, 3-isocyanate butylmethyldimethoxysilane was added dropwise using a continuous feeding method, and a continuous copolymerization reaction was carried out under the action of the catalyst. The addition of 3-isocyanate butylmethyldimethoxysilane was controlled to a cumulative amount of 40g over 80 minutes, and then the dropwise addition was stopped. The reaction rate was maintained until the polymerization conversion of hexamethylene diisocyanate reached 50%, at which point 0. The reaction was terminated with 12g of dioctyl phosphate terminator to obtain an isocyanate mixture solution. Unreacted hexamethylene diisocyanate and 3-isocyanate butylmethyldimethoxysilane were further removed by distillation to obtain polyisocyanate composition 3#. Analysis showed that the NCO content of the polyisocyanate composition was 21.2%, the sum of the contents of free hexamethylene diisocyanate and 3-isocyanate butylmethyldimethoxysilane monomers was 0.51%, the viscosity was 1612cp / 25℃, and the content of mononuclear structure I was 2.8%.

[0082] Example 4

[0083] Under an inert gas atmosphere, 1000g of isophorone diisocyanate was first added to the reaction vessel and heated to 130℃. Then, 0.6g of tetra-n-pentyl zirconium catalyst was added. Simultaneously, 3-isocyanate propyltriethoxysilane was added dropwise using a continuous feeding method, and a continuous copolymerization reaction was carried out under the action of the catalyst. The addition of 3-isocyanate propyltriethoxysilane was controlled to accumulate to 100g over 80 minutes and then stopped. The reaction rate was maintained until the polymerization conversion of isophorone diisocyanate reached 40%, at which point 0. The reaction was terminated with 33g of dioctyl phosphate terminator to obtain an isocyanate mixture solution. Unreacted isophorone diisocyanate and 3-isocyanate propyltriethoxysilane were further removed by distillation to obtain polyisocyanate composition 4#. After analysis, the NCO content of the polyisocyanate composition was 21.0%, the sum of the contents of free isophorone diisocyanate and 3-isocyanate propyltriethoxysilane monomers was 0.80%, the viscosity was 4408cp / 25℃, and the mononuclear structure I content was 17.4%.

[0084] Comparative Example 1

[0085] Compared with Example 3, the only difference is that 3-isocyanate butylmethyldimethoxysilane is not added.

[0086] Under an inert gas atmosphere, 1000g of hexamethylene diisocyanate was first added to the reaction vessel and heated to 105℃. Then, 0.25g of tetra-n-pentanol zirconium catalyst was added, and a continuous polymerization reaction was carried out under the action of the catalyst until the polymerization conversion rate of hexamethylene diisocyanate reached 50%. At this point, 0.12g of dioctyl phosphate terminator was added to terminate the reaction, resulting in an isocyanate mixture solution. Unreacted hexamethylene diisocyanate was further removed by distillation, yielding polyisocyanate composition 5#. Analysis showed that the NCO content of the polyisocyanate composition was 21.8%, the viscosity was 2781 cP / 25℃, the mononuclear structure I content was 0%, and the free hexamethylene diisocyanate content was 0.12%.

[0087] Comparative Example 2

[0088] Compared with Example 4, the only difference is that 3-isocyanate propyltriethoxysilane is not added.

[0089] Under an inert gas atmosphere, 1000g of isophorone diisocyanate was first added to the reaction vessel and heated to 130℃. Then, 0.6g of tetra-n-pentyl zirconium catalyst was added, and a continuous polymerization reaction was carried out under the action of the catalyst until the polymerization conversion rate of isophorone diisocyanate reached 40%. At this point, 0.33g of dioctyl phosphate terminator was added to terminate the reaction, resulting in an isocyanate mixture solution. Unreacted isophorone diisocyanate was further removed by distillation, yielding polyisocyanate composition 6#. Analysis showed that the NCO content of the polyisocyanate composition was 16.9%, the viscosity was >30000cP / 50℃, requiring dilution with butyl acetate before use, the mononuclear structure I content was 0%, and the free isophorone diisocyanate content was 0.70%.

[0090] Examples of the preparation and application of polyisocyanate compositions.

[0091] At 25℃ and relative humidity below 35%, 50g of polyether polyol Wanol F3135, 30g of polyether polyol Puranol D220, and 20g of carbon black filler were added to the adhesive container, along with 0.2g of composite additive AD-4810 and 0.2g of dibutyltin dilaurate. After mechanically stirring and mixing evenly, isocyanate compositions 1-7# were added according to an NCO / OH ratio of 1.07. The mixture was mechanically stirred for 3-10 minutes to ensure uniform mixing. Vacuum was applied at room temperature to remove air bubbles, and the mixture was then poured into a standard mold. The mold used polyethylene terephthalate (PET, purchased from Toyobo, model EcosyarVE500) as the substrate. The mixture was cured at 90℃ for 2 hours and then cured at room temperature for 24 hours to obtain the final test sample.

[0092] (1) Peel strength test: The test sample was cut into 15mm*200mm pieces and a tensile strength tester was used to perform a 180° peel test at a test speed of 50mm / min at 25℃.

[0093] Evaluation criteria: Peel strength ≥10N / 15mm is considered excellent;

[0094] A peel strength of 6N / 15mm ≤ peel strength ≤ 10N / 15mm is considered good.

[0095] A peel strength of 1N / 15mm ≤ peel strength ≤ 6N / 15mm is considered poor.

[0096] (2) High temperature and high humidity hydrolysis resistance test: The test sample was cut into 15mm*200mm pieces, placed in a pressure cooker, and treated at 120℃ and 0.1Mpa for 25 hours. After taking it out, it was aged at room temperature for 1 day. Then, a tensile strength tester was used to perform a 180° peel test at a test speed of 50mm / min.

[0097] Evaluation criteria: Peel strength ≥10N / 15mm is considered excellent;

[0098] A peel strength of 6N / 15mm ≤ peel strength ≤ 10N / 15mm is considered good.

[0099] A peel strength of 1N / 15mm ≤ peel strength ≤ 6N / 15mm is considered poor.

[0100] (3) Weather resistance test: The test sample was cut into 50mm*150mm pieces, and the composite layer was accelerated aging test using a xenon lamp weather resistance tester. The appearance after light aging was observed according to ASTM G155 standard.

[0101] Evaluation criteria: No change is considered excellent;

[0102] Slight discoloration or cracks are acceptable;

[0103] Significant discoloration or cracking indicates a poor result;

[0104] (4) Peel strength test after light exposure: The test sample was cut into 50mm*150mm pieces. The composite layer was subjected to accelerated aging test using a xenon lamp weathering tester. According to ASTM G155 standard, after light exposure, a tensile strength tester was used to perform a 180° peel test at 25℃ and a test speed of 50mm / min.

[0105] Evaluation criteria: Peel strength ≥ 9N / 15mm is considered excellent;

[0106] A peel strength of 5N / 15mm ≤ peel strength ≤ 9N / 15mm is considered good.

[0107] A peel strength of 1N / 15mm ≤ peel strength ≤ 4N / 15mm is considered poor.

[0108] (5) Moist heat aging resistance test: Cut the test sample into 15mm*200mm pieces and put them into a high temperature and high humidity test chamber. The test conditions are: humidity 85%, temperature 85℃, time 1000h. Moist heat aging resistance test is carried out. Observe whether the coating layer has powdering, bubbles, etc. At the same time, the adhesion is tested by cross-cut method. 95% or more without peeling is qualified, and the rest are unqualified.

[0109] Table 1. Overall performance test results of the examples and comparative sample pieces.

[0110]

[0111] As shown in Table 1, the test samples prepared in Examples 1-4 exhibited excellent performance in terms of peel strength, peel strength after high temperature and humidity aging, and weather resistance. The isocyanate composition had low viscosity and did not require the use of additional solvents. In contrast, the test samples prepared in Comparative Examples 1-2 showed significant deficiencies in some indicators. The overall performance of the products decreased significantly after high temperature and humidity aging, and some products required dilution with solvents due to their excessively high viscosity, making it difficult to meet the actual working conditions.

[0112] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A polyisocyanate composition containing siloxane alkyl groups, characterized in that, The polyisocyanate composition comprises a silyl isocyanurate mononuclear structure formed from an aliphatic diisocyanate and an alkoxysilane monoisocyanate, as shown in Formula I: Equation I Wherein, R1 is the residual group of an aliphatic diisocyanate after removing the isocyanate group, R2 is an alkylene group with carbon number between C1 and C8, and R3, R4, and R5 are each independent alkyl or alkoxy groups with carbon number between C1 and C4, and at least one of R3, R4, and R5 is an alkoxy group. In the polyisocyanate composition, the mass fraction of the silane-based isocyanurate mononuclear body is 1-30% based on the total mass of the composition.

2. The composition according to claim 1, characterized in that, In Formula I, two or three of R3, R4, and R5 are alkoxy groups.

3. The composition according to claim 1 or 2, characterized in that, The polyisocyanate composition comprises an aliphatic diisocyanate oligomer, a silyl isocyanurate mononuclear polymer, a free aliphatic diisocyanate monomer, and a free alkoxysilane monoisocyanate.

4. The composition according to claim 3, characterized in that, In the polyisocyanate composition, the sum of the contents of free aliphatic diisocyanate monomer and free alkoxysilane monoisocyanate is less than 1.0%.

5. The composition according to claim 1 or 2, characterized in that, The aliphatic diisocyanate is selected from C4-C atoms containing two terminal isocyanate groups, wherein the isocyanate groups are not directly connected to the benzene ring. 30 Diisocyanate.

6. The composition according to claim 5, characterized in that, The aliphatic diisocyanate is selected from one or more of pentamethylene diisocyanate, hexamethylene diisocyanate, phenyl diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate.

7. The composition according to claim 6, characterized in that, The aliphatic diisocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate.

8. The composition according to claim 1 or 2, characterized in that, The alkoxysilane monoisocyanate is selected from C1-C606 containing terminal isocyanate groups. 10 Alkoxysilanes.

9. The composition according to claim 8, characterized in that, The alkoxysilane monoisocyanate is selected from one or more of 3-isocyanate propylmethyldiethoxysilane, 3-isocyanate propylmethyldimethoxysilane, 3-isocyanate propyltrimethoxysilane, 3-isocyanate propyltriethoxysilane, 3-isocyanate butyltrimethoxysilane, 3-isocyanate butylmethyldimethoxysilane, 3-isocyanate butylmethyldiethoxysilane, and 3-isocyanate butyltriethoxysilane.

10. The composition according to claim 9, characterized in that, The alkoxysilane monoisocyanate is selected from 3-isocyanatepropyltrimethoxysilane and / or 3-isocyanatepropyltriethoxysilane.

11. A method for preparing a polyisocyanate composition containing siloxane, wherein the composition is the polyisocyanate composition according to any one of claims 1-10, characterized in that, The preparation method includes the following steps: Aliphatic diisocyanate and alkoxysilane monoisocyanate react under catalytic conditions, the reaction is terminated to obtain a solution of isocyanate mixture, and unreacted aliphatic diisocyanate and alkoxysilane monoisocyanate are removed to obtain the target polyisocyanate composition. The catalyst is one or more of the following: halogenated quaternary phosphonium salt, halogenated spirocyclic ammonium salt, and metal alkoxide.

12. The preparation method according to claim 11, characterized in that, The reaction temperature is 50-150℃; And / or, the catalyst is one or more of the following: 5-aza-spiro[4.5]decane difluoride, zirconium tetrapentoxide, (2-hydroxyethyl)triphenylphosphonium chloride, and tetrabutylphosphonium difluoride; And / or, the terminating reaction is terminated by adding a terminating agent.

13. The preparation method according to claim 12, characterized in that, The reaction temperature is 100-135℃; The catalyst addition amount is 50-2000 ppm based on the total mass of aliphatic diisocyanate and alkoxysilane monoisocyanate; The reaction is terminated when the polymerization conversion of aliphatic diisocyanate reaches 35-65%.

14. The preparation method according to claim 13, characterized in that, The catalyst addition amount is 100-1000 ppm based on the total mass of aliphatic diisocyanate and alkoxysilane monoisocyanate; The reaction is terminated when the polymerization conversion of aliphatic diisocyanate reaches 40-50%.

15. Use of a polyisocyanate composition containing a siloxane, said composition being the polyisocyanate composition of any one of claims 1-10, or a composition prepared by any one of claims 11-14, said composition being used in coatings or adhesives.

16. The use according to claim 15, characterized in that, The composition is used in automotive coatings or adhesives.

17. The use according to claim 16, characterized in that, The composition is used in polyurethane automotive sealants.

18. A polyurethane automotive sealant, characterized in that, The sealant is made of the polyisocyanate composition according to any one of claims 1-10, or a composition prepared by any one of the preparation methods described in claims 11-14, wherein the sealant uses a polyisocyanate composition containing siloxane as a curing agent.

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