Modified silane coupling agent and preparation method thereof, anti-yellowing dealcoholized sealant, preparation method thereof, and application thereof
By preparing a modified silane coupling agent, the reaction of trimethylsilyl with primary amino groups forms Si-N bonds and a high volume effect, solving the storage stability and anti-yellowing problems of traditional de-alcoholized sealants, and realizing the application of sealants with high stability and long service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HESHENG SILICON (JIAXING) CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-06-23
AI Technical Summary
Traditional alcohol-based sealants have shortcomings in storage stability and anti-yellowing performance, making it difficult to meet the application scenarios with high mechanical reliability requirements, especially in the field of building curtain wall sealing. Furthermore, existing improvement methods, such as adding cyclodextrin metal frame materials or modifying isopropyl titanate catalysts, have side effects.
Modified silane coupling agents were prepared by combining trimethylsilyl silazane compounds with primary amino silane compounds. The oxidation activity of primary amino groups was reduced through Si-N bond formation and high volume effect. Combined with appropriate vacuum treatment, anti-yellowing de-alcoholized sealant was prepared.
It improves the sealant's UV resistance, thermo-oxidative aging resistance, and storage stability, extends its shelf life, reduces the risk of yellowing, and enhances its color stability in harsh environments.
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Abstract
Description
Technical Field
[0001] This application relates to the field of organosilicon sealant technology, and in particular to modified silane coupling agents and their preparation methods, anti-yellowing de-alcoholized sealants and their applications. Background Technology
[0002] Currently, dealcoholized sealants are widely used in construction, automotive, and electronics industries due to their rapid curing and the release of only low-toxicity, environmentally friendly small molecules such as methanol and ethanol during the curing process, which have no corrosive effect on metal and plastic substrates. However, with the expansion of sealant applications, traditional dealcoholized sealants exhibit poor storage stability and resistance to yellowing. For example, the shelf life of dealcoholized sealants currently on the market is generally only 6-9 months, which is insufficient to meet the needs of various applications. On the other hand, although some dealcoholized sealants use surface drying time changes as test data to evaluate their storage stability, the long-term retention of their mechanical properties is not considered.
[0003] Based on this, the applicant, through actual sampling and testing of several mainstream de-alcoholized sealant samples on the market, found that although some test samples showed no significant abnormalities in surface drying time during storage and could undergo normal curing reactions, the mechanical properties of the cured products deteriorated severely after aging; for example, the retention rate of tensile strength was only 20% to 30%. These poor mechanical properties make these de-alcoholized sealants unsuitable for applications requiring high mechanical reliability, such as in building curtain wall sealing, leading to a high risk of seal failure and potential structural loosening.
[0004] Therefore, in order to increase the storage stability and curing performance of de-alcoholized sealants, it is urgent to develop a de-alcoholized sealant and its preparation process that can produce a sealant with long storage life, low yellowing risk and high storage stability. Summary of the Invention
[0005] One objective of this application is to provide a modified silane coupling agent and its preparation method, an anti-yellowing de-alcoholized sealant and its application, which is beneficial to increasing the storage life and storage stability of the anti-yellowing de-alcoholized sealant, reducing the risk of yellowing, and further increasing market competitiveness.
[0006] To achieve the above objectives, this application provides a method for preparing a modified silane coupling agent, comprising the following steps: S100: mixing a silazane compound and a silane compound to obtain a coupling agent precursor, wherein the silazane compound has a trimethylsilyl group and the silane compound has a primary amino group; S200: heating the coupling agent precursor under vacuum conditions to remove low-boiling substances from the coupling agent precursor, and then cooling to obtain the modified silane coupling agent.
[0007] In some embodiments, the preparation method satisfies at least one of the following conditions: the molar ratio of the trimethylsilyl group to the primary amino group is (1~2):1; the silazane compound is at least one of N-methylhexamethyldisilazane, octamethyltrisilazane, and hexamethyldisilazane, and the silane compound is at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane; when the silazane compound is hexamethyldisilazane and the silane compound is γ-aminopropyltriethoxysilane, the molar ratio of the hexamethyldisilazane to the γ-aminopropyltriethoxysilane is 1:(1~2); the blending temperature in step S100 is 70℃~90℃, and the blending time is 3h~6h; the heating temperature in step S200 is 80℃~100℃, and the heating time is 1h~6h; the vacuum degree in step S200 is -0.1MPa~-0.08MPa.
[0008] To achieve the above objectives, this application provides a modified silane coupling agent prepared by the aforementioned preparation method.
[0009] To achieve the above objectives, this application provides an anti-yellowing, alcohol-free sealant, comprising: a modified silane coupling agent as described above, α,ω-dihydroxy polydimethylsiloxane, a crosslinking agent, and a catalyst, wherein the α,ω-dihydroxy polydimethylsiloxane is present in a mass fraction of 40 to 70 parts, the crosslinking agent in a mass fraction of 2 to 10 parts, the modified silane coupling agent in a mass fraction of 0.5 to 5 parts, and the catalyst in a mass fraction of 0.5 to 2 parts.
[0010] In some embodiments, the anti-yellowing de-alcoholized sealant satisfies at least one of the following conditions: the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 20000 mPa·s to 80000 mPa·s; the crosslinking agent is a mixture of methyltrimethoxysilane and phenyltrimethoxysilane, wherein the mass ratio of methyltrimethoxysilane to phenyltrimethoxysilane is (1~2):1; and the catalyst is at least one of bis(ethyl acetoacetate) titanate, tetrabutyl titanate, and tetraisopropyl titanate.
[0011] In some embodiments, the anti-yellowing de-alcoholized sealant further includes dimethyl silicone oil and filler, wherein the dimethyl silicone oil is present in parts by weight of 2 to 10 parts and the filler is present in parts by weight of 30 to 60 parts.
[0012] In some embodiments, the anti-yellowing de-alcoholized sealant meets at least one of the following conditions: the viscosity of the dimethyl silicone oil at 25°C is 100 mPa·s to 500 mPa·s; the filler is at least one of nano-activated calcium carbonate, heavy calcium carbonate, and fumed silica; and the particle size of the filler is 30 nm to 150 nm.
[0013] To achieve the above objectives, this application provides a method for preparing an anti-yellowing dealcoholized sealant, comprising the following steps: A100: providing α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil, filler, modified silane coupling agent, crosslinking agent, and catalyst as described above; and performing dehydration and homogenization treatment on the α,ω-dihydroxy polydimethylsiloxane, the dimethyl silicone oil, and the filler under vacuum conditions to obtain a first base material; A200: under vacuum conditions, blending a portion of the crosslinking agent and the first base material to obtain a second base material; A300: under vacuum conditions, blending another portion of the crosslinking agent, the modified silane coupling agent, and the catalyst to obtain an anti-yellowing dealcoholized sealant.
[0014] In some embodiments, the preparation method satisfies at least one of the following conditions: in step A100, the temperature of the dehydration and homogenization treatment is 110℃~130℃, the time of the dehydration and homogenization treatment is 2h~4h, and the vacuum degree is -0.1MPa~-0.08MPa; in step A200, the blending amount of the crosslinking agent accounts for 70%~90% of the total amount of the crosslinking agent, the blending time is 20min~60min, and the vacuum degree is -0.1MPa~-0.08MPa; in step A300, the blending amount of the crosslinking agent accounts for 10%~30% of the total amount of the crosslinking agent, the blending time is 20min~60min, and the vacuum degree is -0.1MPa~-0.08MPa.
[0015] To achieve the above objectives, this application also provides the application of the aforementioned modified anti-yellowing de-alcoholized sealant or the anti-yellowing de-alcoholized sealant prepared by the aforementioned preparation method in the sealing and bonding of electronic appliances, buildings, automobiles, handicrafts, and LED lighting fixtures.
[0016] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application prepares modified silane coupling agents by using silazane compounds with trimethylsilyl groups and silane compounds with primary amino groups. This is beneficial for reducing the oxidative activity of primary amino groups in silane compounds, thereby improving UV resistance, thermo-oxidative aging resistance, and storage stability, so that they can maintain color stability even after long-term use or in harsh environments. On the one hand, since the trimethylsilyl group in the silazane compound reacts with the primary amino group of the silane compound to form Si-N bonds, the content of primary amino groups is reduced compared to traditional amine coupling agents. On the other hand, the trimethylsilyl group with high volume effect provides high physical steric hindrance, thereby reducing the risk of oxygen or water and other substances contacting the primary amino group, and further reducing the risk of oxidation reaction of the primary amino group. Furthermore, since the trimethylsilyl group has strong hydrophobicity, it is beneficial for reducing the risk of water and oxygen, which are prone to oxidative yellowing, especially the risk of reactants that cause oxidation of primary amino groups, penetrating and contacting the primary amino group.
[0017] (2) The anti-yellowing dealcohol type sealant provided in this application uses the modified silane coupling agent provided in this application. The modified silane coupling agent with good storage stability and storage life further increases the storage stability and storage life of the anti-yellowing dealcohol type sealant, and can also reduce the risk of yellowing of the anti-yellowing dealcohol type sealant. Detailed Implementation
[0018] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0019] As used herein, the terms “prepared from” and “comprising” are synonymous. The terms “comprising,” “including,” “having,” “containing,” or any other variation thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements and may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.
[0020] When a quantity, concentration, or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range is disclosed as “1 to 5”, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range includes its endpoints and all integers and fractions within that range.
[0021] Approximate terms used in the specification and claims to modify quantities indicate that the invention is not limited to that specific quantity, but also includes acceptable modifications close to that quantity that do not alter the relevant essential function. Correspondingly, the use of "about," "approximately," etc., to modify a numerical value means that the invention is not limited to that precise value. In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In this application's specification and claims, scope definitions can be combined and / or interchanged, unless otherwise stated, these scopes include all subscopes contained therein.
[0022] The applicant found that although the industry can extend shelf life by adding cyclodextrin metal framework materials to remove free hydroxyl groups in dealcoholized sealants, the reinforcing effect of cyclodextrin metal framework materials is poor, and large quantities are required, which significantly affects the mechanical properties of dealcoholized sealants. Furthermore, while dealcoholized sealants with added cyclodextrin metal framework materials can cure normally after 18 months of storage, the surface drying time is extended by approximately two times, reducing their versatility.
[0023] Furthermore, the industry has also used modified isopropyl titanate catalysts to maintain catalyst activity and thus improve storage stability. However, the introduction of salicylate esters can easily cause yellowing of dealcoholized sealants. In addition, amino coupling agents used in combination with modified isopropyl titanate catalysts are also prone to yellowing, thus reducing the stability of dealcoholized sealants in use.
[0024] Based on this, this application provides a method for preparing a modified silane coupling agent, comprising the following steps: S100: mixing a silazane compound and a silane compound to obtain a coupling agent precursor, wherein the silazane compound has a trimethylsilyl group and the silane compound has a primary amino group; S200: heating the coupling agent precursor under vacuum conditions to remove low-boiling substances from the coupling agent precursor, and obtaining the modified silane coupling agent after cooling.
[0025] It is worth mentioning that this application prepares modified silane coupling agents using silazane compounds with trimethylsilyl groups and silane compounds with primary amino groups. This is beneficial for reducing the oxidative activity of primary amino groups in silane compounds, thereby improving UV resistance, thermo-oxidative aging resistance, and storage stability, allowing them to maintain color stability even after long-term use or in harsh environments. On the one hand, because the trimethylsilyl group in the silazane compound reacts with the primary amino group of the silane compound to form a Si-N bond, the content of primary amino groups is reduced compared to traditional amine coupling agents. On the other hand, the trimethylsilyl group with high volume effect provides high physical steric hindrance, thereby reducing the risk of oxygen or water contacting the primary amino group, further reducing the risk of oxidation of the primary amino group. Furthermore, because the trimethylsilyl group has strong hydrophobicity, it is beneficial for reducing the risk of moisture and oxygen, which easily cause oxidative yellowing, especially the risk of reactants that cause primary amino oxidation, penetrating and contacting the primary amino group.
[0026] On the other hand, the trimethylsilyl group in silazane compounds can also consume the silanol groups in silane compounds, further reducing the number of active groups, which is beneficial to extending the storage life and storage stability of de-alcoholized sealants.
[0027] In some embodiments, the molar ratio of trimethylsilyl group to primary amino group is (1~2):1. This is because, in the theoretical reaction process, one trimethylsilyl group reacts with one primary amino group to form a Si-N bond, reducing the number of primary amino groups. On the other hand, the trimethylsilyl group has a high volume effect, which can protect the primary amino group. Based on this, appropriately increasing the amount of trimethylsilyl group used is beneficial to enhance the protective performance of the primary amino group and further improve the stability of the modified silane coupling agent.
[0028] In some embodiments, the silazane compound is at least one selected from N-methylhexamethyldisilazane, octamethyltrisilazane, and hexamethyldisilazane, and the silane compound is at least one selected from γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane. By selecting suitable silazane and silane compounds to stably provide trimethylsilyl and primary amino groups, the protective performance of the trimethylsilyl group on the primary amino group is enhanced, thereby increasing the stability of the prepared modified silane coupling agent in use.
[0029] In some embodiments, the silazane compound is hexamethyldisilazane, the silane compound is γ-aminopropyltriethoxysilane, and the molar ratio of hexamethyldisilazane to γ-aminopropyltriethoxysilane is 1:(1~2). Specifically, the molar ratio of hexamethyldisilazane to γ-aminopropyltriethoxysilane can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2. It should be understood that in the theoretical reaction process, the trimethylsilyl group in hexamethyldisilazane reacts with the primary amino group in γ-aminopropyltriethoxysilane to form a Si-N bond, meaning the ratio of trimethylsilyl group to primary amino group should be 1:1. However, hexamethyldisilazane contains two trimethylsilyl groups that can react simultaneously with silanol groups, meaning that one hexamethyldisilazane can react with two γ-aminopropyltriethoxysilanes at the same time. Therefore, it is necessary to appropriately increase the amount of hexamethyldisilazane used to increase the degree of silanol group consumption in the γ-aminopropyltriethoxysilane.
[0030] It is worth mentioning that this application prepares a modified silane coupling agent by reacting hexamethyldisilazane with γ-aminopropyltriethoxysilane, which helps to reduce the oxidative activity of the amino groups in γ-aminopropyltriethoxysilane, thereby improving the UV resistance, thermo-oxidative aging resistance, and storage stability of the anti-yellowing, alcohol-based sealant, allowing it to maintain color stability even after long-term use or in harsh environments. On the one hand, the trimethylsilyl group in hexamethyldisilazane reacts with the primary amino group in γ-aminopropyltriethoxysilane to form Si-N bonds, reducing the number of primary amino groups. On the other hand, the trimethylsilyl group has a high volume effect, thereby reducing the risk of oxygen or water contacting the amino group, further reducing the risk of oxidation. Furthermore, the strong hydrophobicity of the trimethylsilyl group helps to reduce the risk of moisture and oxygen, which easily cause oxidative yellowing, especially the risk of reactants that cause amino oxidation, penetrating and contacting the amino group.
[0031] On the other hand, the trimethylsilyl group in hexamethyldisilazane can also consume the silanol group in γ-aminopropyltriethoxysilane, further reducing the number of active groups, which is beneficial to extending the storage life and storage stability of the de-alcoholized sealant.
[0032] It is worth noting that when the amount of hexamethyldisilazane is too small, a large number of silanol groups in γ-aminopropyltriethoxysilane do not participate in the reaction. This means that a large number of reactive primary amino groups and silanol groups remain in the modified silane coupling agent, thus reducing its shelf life and storage stability, and exacerbating yellowing. When the amount of hexamethyldisilazane is too large, γ-aminopropyltriethoxysilane is excessively coated with hexamethyldisilazane, causing the amino groups to be overly shielded and reducing adhesive activity. Therefore, selecting appropriate amounts of hexamethyldisilazane and γ-aminopropyltriethoxysilane is beneficial for improving the shelf life and storage stability of the prepared modified silane coupling agent, further reducing the risk of yellowing.
[0033] In some embodiments, the blending temperature in step S100 is 70°C to 90°C, and the blending time is 3 hours to 6 hours. It is understood that the blending temperature can be 70°C, 75°C, 80°C, 85°C, or 90°C, and the blending time can be 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours. Selecting suitable blending conditions is beneficial for obtaining a highly uniform coupling agent precursor.
[0034] In some embodiments, the heating temperature in step S200 is 80℃~100℃, and the heating time is 1h~6h; the vacuum degree in step S200 is -0.1MPa~-0.08MPa. It is understood that the heating temperature can be 80℃, 85℃, 90℃, 95℃, or 100℃, and the heating time can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, or 6h. By selecting suitable blending conditions, it is beneficial to obtain highly uniform modified silane coupling agents.
[0035] It is worth mentioning that, when using the modified silane coupling agent provided in this application, by changing some parameters in the preparation process within the parameter range provided in this application, modified silane coupling agents with different degrees of reaction between silazane compounds and silane compounds can be obtained. For example, by changing parameters such as vacuum degree, blending temperature, or processing time, modified silane coupling agent A and modified silane coupling agent B can be obtained. In practical use, modified silane coupling agent A and / or modified silane coupling agent B can be used simultaneously, thereby achieving fine-tuning of the anti-yellowing and adhesive properties of the anti-yellowing and de-alcoholizing sealant when added to it, increasing the applicability of the modified silane coupling agent.
[0036] This application provides a modified silane coupling agent prepared by the aforementioned method. The preparation method provided in this application improves the shelf life and storage stability of the prepared modified silane coupling agent, further reducing the risk of yellowing.
[0037] This application provides an anti-yellowing and de-alcoholizing sealant, comprising: a modified silane coupling agent as described above, α,ω-dihydroxy polydimethylsiloxane, a crosslinking agent, and a catalyst, wherein the α,ω-dihydroxy polydimethylsiloxane is present in parts by weight of 40 to 70, the crosslinking agent in parts by weight of 2 to 10, the modified silane coupling agent in parts by weight of 0.5 to 5, and the catalyst in parts by weight of 0.5 to 2.
[0038] It is understood that the anti-yellowing dealcoholizing sealant provided in this application uses α,ω-dihydroxy polydimethylsiloxane as the basic polymer backbone. Under the action of a catalyst, the silanol groups at the ends of the α,ω-dihydroxy polydimethylsiloxane can undergo a dealcoholization condensation reaction with a crosslinking agent, forming a three-dimensionally connected network of elastic silicone rubber matrix for the anti-yellowing dealcoholizing sealant. Furthermore, the main chain of the elastic silicone rubber matrix is composed of Si-O-Si bonds, possessing high bond energy, which gives the anti-yellowing dealcoholizing sealant excellent resistance to ultraviolet radiation, ozone, and high and low temperatures.
[0039] In some embodiments, the viscosity of α,ω-dihydroxypolydimethylsiloxane at 25°C is 20000 mPa·s to 80000 mPa·s; the crosslinking agent is a mixture of methyltrimethoxysilane and phenyltrimethoxysilane, with a mass ratio of methyltrimethoxysilane to phenyltrimethoxysilane of (1~2):1. It is understood that the three methoxy groups in methyltrimethoxysilane are linked to methylsilane, resulting in low steric hindrance and high crosslinking density and curing speed. Furthermore, by combining methyltrimethoxysilane and phenyltrimethoxysilane, the benzene ring structure in phenyltrimethoxysilane exhibits extremely high thermal stability and UV absorption capacity, which is beneficial for enhancing the heat resistance and UV aging resistance of anti-yellowing and de-alcoholized sealants.
[0040] In some embodiments, the catalyst is at least one of bis(ethyl acetoacetate) titanate diisopropyl, tetrabutyl titanate, and tetraisopropyl titanate. By selecting a suitable catalyst and dosage, it is beneficial to obtain an anti-yellowing de-alcoholized sealant with good weather resistance, storage stability, and shelf life.
[0041] In some embodiments, the anti-yellowing de-alcoholized sealant further includes dimethyl silicone oil and filler, wherein the dimethyl silicone oil is present in parts by weight of 2 to 10 parts, and the filler is present in parts by weight of 30 to 60 parts. It is understood that dimethyl silicone oil can act as a process and performance modifier to reduce the viscosity of the adhesive, resulting in a more uniform distribution of internal stress and reducing the risk of internal cracking due to shrinkage or deformation. On the other hand, the filler helps to reduce volume shrinkage during the curing process, further improving sealing performance and bonding reliability.
[0042] In some embodiments, the viscosity of dimethyl silicone oil at 25°C is 100 mPa·s to 500 mPa·s. By selecting dimethyl silicone oil with a suitable viscosity, the internal stress distribution of the adhesive can be made more uniform, reducing the risk of internal cracking caused by shrinkage or deformation. This is beneficial for producing anti-yellowing de-alcoholized sealant with good weather resistance, storage stability and storage life.
[0043] In some embodiments, the filler is at least one of nano-activated calcium carbonate, heavy calcium carbonate, and fumed silica, with a particle size of 30 nm to 150 nm. Specifically, the particle size of the filler is 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm. The light calcium carbonate is activated nano-calcium carbonate treated with stearic acid or a silane coupling agent, and has a cubic crystal form. By selecting appropriate fillers and dosages, it is beneficial to obtain an anti-yellowing, de-alcoholized sealant with good weather resistance, storage stability, and shelf life.
[0044] This application provides a method for preparing an anti-yellowing dealcoholized sealant, comprising the following steps: A100: providing α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil, filler, modified silane coupling agent, crosslinking agent, and catalyst as described above; and performing dehydration and homogenization treatment on the α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil, and filler under vacuum conditions to obtain a first base material; A200: under vacuum conditions, blending a portion of the crosslinking agent and the first base material to obtain a second base material; A300: under vacuum conditions, blending another portion of the crosslinking agent, modified silane coupling agent, and catalyst to obtain an anti-yellowing dealcoholized sealant. A suitable preparation method facilitates the preparation of an anti-yellowing dealcoholized sealant with good performance stability and service life. Furthermore, since the anti-yellowing dealcoholized sealant provided in this application uses the modified silane coupling agent provided in this application, the modified silane coupling agent, which has good storage stability and shelf life, further increases the storage stability and shelf life of the anti-yellowing dealcoholized sealant, and can also reduce the risk of yellowing of the anti-yellowing dealcoholized sealant.
[0045] In some embodiments, in step A100, the temperature of the dehydration and homogenization treatment is 110°C to 130°C, the time of the dehydration and homogenization treatment is 2 hours to 4 hours, and the vacuum degree is -0.1 MPa to -0.08 MPa. By selecting suitable dehydration and homogenization treatment conditions, it is beneficial to obtain a highly uniform first base material.
[0046] In some embodiments, in step A200, the amount of crosslinking agent in the blend accounts for 70% to 90% of the total amount of crosslinking agent, the blending time is 20 min to 60 min, and the vacuum degree is -0.1 MPa to -0.08 MPa. By selecting suitable blending conditions, it is beneficial to obtain a highly uniform second base material.
[0047] In some embodiments, in step A300, the amount of crosslinking agent in the blend accounts for 10% to 30% of the total amount of crosslinking agent, the blending time is 20 min to 60 min, and the vacuum degree is -0.1 MPa to -0.08 MPa. By selecting suitable blending conditions, it is beneficial to obtain a highly uniform anti-yellowing de-alcoholized sealant.
[0048] This application also provides the application of the aforementioned modified anti-yellowing de-alcoholized sealant or the anti-yellowing de-alcoholized sealant prepared by the aforementioned preparation method in the sealing and bonding of electronic appliances, buildings, automobiles, handicrafts, and LED lighting fixtures. It should be understood that, due to its good storage stability and long shelf life, and low risk of yellowing, the anti-yellowing de-alcoholized sealant can be used stably in various application scenarios.
[0049] Example 1 A method for preparing a modified silane coupling agent and an anti-yellowing, alcohol-based sealant, comprising the following steps: (1) Prepare a mixture of hexamethyldisilazane and γ-aminopropyltriethoxysilane in a molar ratio of 1:1.5, heat it to 75°C and keep it at the temperature for 6 hours, remove low-boiling substances by vacuum rotary evaporation to obtain modified silane coupling agent.
[0050] (2) By mass, 50 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 20000 mPa·s at 25℃, 40 parts of active nano calcium carbonate, and 5 parts of dimethyl silicone oil were added to a kneader and dehydrated and mixed for 4 hours at 110℃ and a vacuum of -0.09 MPa. The mixture was then cooled to room temperature. Then, 4 parts of crosslinking agent (the mass ratio of methyltrimethoxysilane to phenyltrimethoxysilane in the crosslinking agent was 2:1) were added and stirred and mixed for 30 min at a vacuum of -0.09 MPa and room temperature. Finally, 1 part of crosslinking agent, 3 parts of modified silane coupling agent, and 1 part of diisopropyl bis(ethyl acetoacetate) titanate were added and stirred and mixed for 20 min at a vacuum of -0.09 MPa and room temperature to obtain an anti-yellowing de-alcoholized sealant. The sealant was then filled into plastic tubes under nitrogen protection for later use.
[0051] Example 2 A method for preparing a modified silane coupling agent and an anti-yellowing, alcohol-based sealant, comprising the following steps: (1) Prepare a mixture of hexamethyldisilazane and γ-aminopropyltriethoxysilane in a molar ratio of 1:2, heat to 85°C and keep warm for 5 hours, remove low-boiling substances by vacuum rotary evaporation to obtain modified silane coupling agent.
[0052] (2) By mass, 55 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s at 25℃, 45 parts of active nano calcium carbonate, and 3 parts of dimethyl silicone oil were added to a kneader and dehydrated and mixed for 3 hours at 120℃ and a vacuum of -0.09 MPa. The mixture was then cooled to room temperature. Then, 4.5 parts of crosslinking agent (the mass ratio of methyltrimethoxysilane to phenyltrimethoxysilane in the crosslinking agent was 2:1) were added and stirred and mixed for 30 minutes at a vacuum of -0.09 MPa and room temperature. Finally, 0.5 parts of crosslinking agent, 4 parts of modified silane coupling agent, and 0.8 parts of tetraisopropyl titanate were added and stirred and mixed for 30 minutes at a vacuum of -0.09 MPa and room temperature to obtain an anti-yellowing de-alcoholized sealant. The sealant was then filled into plastic tubes under nitrogen protection for later use.
[0053] Example 3 The difference between Example 3 and Example 1 is that hexamethyldisilazane is replaced with octamethyltrisilazane.
[0054] Example 4 The difference between Example 4 and Example 1 is that hexamethyldisilazane is replaced with N-methylhexamethyldisilazane.
[0055] Example 5 The difference between Example 5 and Example 1 is that γ-aminopropyltriethoxysilane is replaced with γ-aminopropyltrimethoxysilane.
[0056] Example 6 The difference between Example 6 and Example 1 is that hexamethyldisilazane and γ-aminopropyltriethoxysilane are in a molar ratio of 1:2.
[0057] Example 7 The difference between Example 7 and Example 1 is that hexamethyldisilazane and γ-aminopropyltriethoxysilane are in a molar ratio of 1:1.
[0058] Comparative Example 1 A method for preparing an anti-yellowing, de-alcoholized sealant includes the following steps: 45 parts by weight of α,ω-dihydroxypolydimethylsiloxane (viscosity 80000 mPa·s at 25°C), 55 parts by weight of active nano-calcium carbonate, and 8 parts by weight of dimethyl silicone oil are added to a kneader and mixed under conditions of 130°C and -0.09 MPa vacuum for 2 hours, then cooled to room temperature; then 4 parts by weight of a crosslinking agent (the mass ratio of methyltrimethoxysilane to phenyltrimethoxysilane in the crosslinking agent is 2:1) are added, and the mixture is stirred and mixed under conditions of -0.09 MPa vacuum and room temperature for 25 minutes; finally, 0.5 parts by weight of the crosslinking agent, 2.5 parts by weight of γ-aminopropyltriethoxysilane, and 0.5 parts by weight of tetrabutyl titanate are added, and the mixture is stirred and mixed under conditions of -0.09 MPa vacuum and room temperature for 35 minutes to obtain the anti-yellowing, de-alcoholized sealant, which is then filled into plastic containers under nitrogen protection for later use.
[0059] Comparative Example 2 The difference between Comparative Example 2 and Comparative Example 1 is that 2.5 parts of γ-aminopropyltriethoxysilane were replaced with 2.5 parts of hexamethyldisilazane.
[0060] Comparative Example 3 A method for preparing an anti-yellowing, de-alcoholized sealant includes the following steps: 45 parts by weight of α,ω-dihydroxypolydimethylsiloxane (viscosity 80000 mPa·s at 25°C), 55 parts by weight of active nano-calcium carbonate, and 8 parts by weight of dimethyl silicone oil are added to a kneader and mixed under a temperature of 130°C and a vacuum of -0.09 MPa for 2 hours, then cooled to room temperature; then 4 parts by weight of methyltrimethoxysilane are added and mixed under a vacuum of -0.09 MPa and room temperature for 25 minutes; finally, 2.5 parts by weight of γ-aminopropyltriethoxysilane and 0.5 parts by weight of tetrabutyl titanate are added and mixed under a vacuum of -0.09 MPa and room temperature for 35 minutes to obtain the anti-yellowing, de-alcoholized sealant, which is then filled into plastic containers under nitrogen protection for later use.
[0061] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the molar ratio of hexamethyldisilazane to γ-aminopropyltriethoxysilane is 1:5.
[0062] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the molar ratio of hexamethyldisilazane to γ-aminopropyltriethoxysilane is 1:0.5.
[0063] Performance testing The performance of the anti-yellowing de-alcoholized sealants prepared in Examples 1-7 and Comparative Examples 1-5 was tested, and the test data are shown in Table 1.
[0064] Table 1. Performance Tests of Anti-Yellowing and De-Alcoholized Sealants
[0065] Examples 1-6 demonstrate that selecting appropriate processing conditions, trimethylsilane compounds, and silane compounds with primary amino groups and hydrolyzable silicon functional groups during the preparation of modified silane coupling agents and anti-yellowing de-alcoholized sealants is beneficial for obtaining anti-yellowing de-alcoholized sealants with long shelf life and high storage stability, reducing the risk of yellowing and further increasing market competitiveness. Examples 1, 6-7, and Comparative Examples 4-5 show that when the amount of hexamethyldisilazane is too small, a large number of silanol groups in γ-aminopropyltriethoxysilane do not participate in the reaction, meaning that a large number of active primary amino groups and silanol groups remain in the modified silane coupling agent, thereby reducing the shelf life and storage stability of the modified silane coupling agent and exacerbating the yellowing phenomenon. When the amount of hexamethyldisilazane is too large, γ-aminopropyltriethoxysilane is encapsulated by excessive hexamethyldisilazane, causing excessive shielding of the amino groups and reducing adhesive activity. Therefore, selecting appropriate amounts of hexamethyldisilazane and γ-aminopropyltriethoxysilane is beneficial for improving the shelf life and storage stability of the prepared modified silane coupling agent, and further reducing the risk of yellowing. Furthermore, appropriately increasing the amount of hexamethyldisilazane is beneficial for increasing the reaction consumption of silanol groups in γ-aminopropyltriethoxysilane. Comparative Examples 1 and 1-5 show that by selecting appropriate preparation conditions, it is beneficial to obtain an anti-yellowing, de-alcoholized sealant with low yellowing risk, long shelf life, and high storage stability.
[0066] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a modified silane coupling agent, characterized in that, Including the following steps: S100: A coupling agent precursor is prepared by mixing a silazane compound and a silane compound, wherein the silazane compound has a trimethylsilyl group and the silane compound has a primary amino group; S200: The coupling agent precursor is heated under vacuum conditions to remove low-boiling substances from the coupling agent precursor, and then cooled to obtain a modified silane coupling agent.
2. The preparation method according to claim 1, characterized in that, At least one of the following conditions must be met: The molar ratio of the trimethylsilyl group to the primary amino group is (1~2):1; The silazane compound is at least one of N-methylhexamethyldisilazane, octamethyltrisilazane, and hexamethyldisilazane, and the silane compound is at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane. When the silazane compound is hexamethyldisilazane and the silane compound is γ-aminopropyltriethoxysilane, the molar ratio of hexamethyldisilazane to γ-aminopropyltriethoxysilane is 1:(1~2). In step S100, the blending temperature is 70℃~90℃ and the blending time is 3h~6h. The temperature for the heating process in step S200 is 80℃~100℃, the heating time is 1h~6h, and the vacuum degree in step S200 is -0.1MPa~-0.08MPa.
3. A modified silane coupling agent, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 2.
4. A yellowing-resistant, alcohol-free sealant, characterized in that, include: The modified silane coupling agent, α,ω-dihydroxy polydimethylsiloxane, crosslinking agent, and catalyst as described in claim 3, wherein the α,ω-dihydroxy polydimethylsiloxane has a mass fraction of 40 to 70 parts, the crosslinking agent has a mass fraction of 2 to 10 parts, the modified silane coupling agent has a mass fraction of 0.5 to 5 parts, and the catalyst has a mass fraction of 0.5 to 2 parts.
5. The anti-yellowing and de-alcoholizing sealant according to claim 4, characterized in that, At least one of the following conditions must be met: The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 20000 mPa·s to 80000 mPa·s. The crosslinking agent is a mixture of methyltrimethoxysilane and phenyltrimethoxysilane, wherein the mass ratio of methyltrimethoxysilane to phenyltrimethoxysilane is (1~2):1; The catalyst is at least one of bis(ethyl acetoacetate) titanate diisopropyl, tetrabutyl titanate, and tetraisopropyl titanate.
6. The anti-yellowing and de-alcoholizing sealant according to claim 4, characterized in that, The anti-yellowing de-alcoholized sealant also includes dimethyl silicone oil and filler, wherein the dimethyl silicone oil is present in parts by weight of 2 to 10 parts and the filler is present in parts by weight of 30 to 60 parts.
7. The anti-yellowing and de-alcoholizing sealant according to claim 6, characterized in that, At least one of the following conditions must be met: The viscosity of the dimethyl silicone oil at 25°C is 100 mPa·s to 500 mPa·s. The filler is at least one of nano-activated calcium carbonate, heavy calcium carbonate, and fumed silica. The particle size of the filler is 30nm to 150nm.
8. A method for preparing an anti-yellowing, alcohol-based sealant, characterized in that, Including the following steps: A100: Provides the α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil, filler, modified silane coupling agent, crosslinking agent and catalyst as described in claim 4, wherein the α,ω-dihydroxy polydimethylsiloxane, the dimethyl silicone oil and the filler are subjected to dehydration and homogenization treatment under vacuum conditions to obtain a first base material; A200: Under vacuum conditions, a portion of the crosslinking agent and the first base material are blended together to obtain the second base material; A300: Under vacuum conditions, another portion of the crosslinking agent, the modified silane coupling agent, and the catalyst are blended to obtain an anti-yellowing de-alcoholized sealant.
9. The preparation method according to claim 8, characterized in that, At least one of the following conditions must be met: In step A100, the temperature of the dehydration and homogenization treatment is 110℃~130℃, the time of the dehydration and homogenization treatment is 2h~4h, and the vacuum degree is -0.1MPa~-0.08MPa; In step A200, the amount of crosslinking agent used in the blend accounts for 70% to 90% of the total amount of crosslinking agent used, the blending time is 20 min to 60 min, and the vacuum degree is -0.1 MPa to -0.08 MPa. In step A300, the amount of crosslinking agent used in the blend is 10% to 30% of the total amount of crosslinking agent used, the blending time is 20 min to 60 min, and the vacuum degree is -0.1 MPa to -0.08 MPa.
10. The application of the anti-yellowing de-alcoholized sealant according to any one of claims 4 to 7 or the anti-yellowing de-alcoholized sealant prepared by the preparation method according to any one of claims 8 to 9 in the sealing and bonding of electronic appliances, buildings, automobiles, handicrafts, and LED lamps.