An environment-friendly acid silicone sealant for aquariums and a preparation method thereof

Abstract

The present application relates to an environment-friendly acid silicone sealant for aquarium and a preparation method thereof, and belongs to the technical field of sealant. The present application provides a silicone sealant system containing long-chain alcohol ester of ferulic acid modified silane coupling agent and hexamethyldisilazane modified hydrophobic fumed silica. Among them, the long-chain alkyl group introduced by long-chain alcohol ester of ferulic acid endows the sealant with excellent hydrophobic and water resistance, and the synergistic effect of phenolic hydroxyl and conjugated double bond endows the material with efficient antioxidant, anti-yellowing and natural antibacterial ability; in combination with the synergistic curing mechanism of the hydrophobic filling effect of modified fumed silica and the catalyst, the long-term water resistance and mechanical stability of the sealant are improved. The synergistic effect of each component of the present application makes the sealant have excellent water resistance, aging resistance, mildew resistance, algae resistance and hydrophobicity, and at the same time, the use of bio-based raw materials makes the source more environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of sealant technology, specifically relating to an environmentally friendly acidic silicone sealant for aquariums and its preparation method. Background Technology

[0002] Silicone sealants are sealing materials with polysiloxane as the main component. Among them, acidic silicone sealants use acetoxysilane as a crosslinking agent. They release small molecules of acetic acid through room temperature and humidity curing. They have advantages such as fast curing speed, good adhesion to glass and other substrates, and low cost. They are widely used in glass bonding and sealing scenarios such as glass curtain walls, insulated glass, and aquariums.

[0003] However, underwater environments such as aquariums place more stringent demands on the performance of silicone sealants, and the shortcomings of existing acidic silicone sealants during long-term underwater service have gradually become apparent.

[0004] On the one hand, prolonged immersion of sealants in water allows water molecules to continuously penetrate the colloid, triggering hydrolysis and degradation of the polysiloxane backbone and weakening the interfacial bonding between the filler and the matrix. This leads to a significant decrease in mechanical strength over time, ultimately resulting in adhesion failure and leakage risks. On the other hand, aquarium water is rich in nutrients, making the sealant surface highly susceptible to algae and bacteria growth. The resulting biofilm not only affects aesthetics but also accelerates material surface deterioration. Current solutions primarily rely on adding organic bactericides, but these additives are slowly released during prolonged immersion, posing a potential hazard to aquatic life. Furthermore, the anti-mold effect rapidly diminishes after the bactericides are consumed, making long-term protection difficult. In addition, increasingly stringent environmental regulations and the growing emphasis on sustainable development have led to widespread attention on bio-based materials in the sealant field. However, existing products still primarily use petrochemical-based raw materials, indicating a significant gap in greenness.

[0005] In summary, existing acidic silicone sealants for aquariums still have significant shortcomings in terms of long-term underwater water resistance, anti-yellowing durability, antimicrobial adhesion ability, and process stability. There is an urgent need to develop a new silicone sealant material system that combines excellent performance with environmental friendliness. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides an environmentally friendly acidic silicone sealant for aquariums and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions: An environmentally friendly acidic silicone sealant for aquariums comprises α,ω-dihydroxypolydimethylsiloxane, and based on 100 parts of said α,ω-dihydroxypolydimethylsiloxane, further comprises the following components by weight: 15-25 parts dimethyl silicone oil; 8-12 parts filler; 6-10 parts crosslinking agent; 1-3 parts modified coupling agent; 0.3-0.5 parts catalyst; The crosslinking agent is a mixture of methyltriacetoxysilane and vinyltriacetoxysilane in a weight ratio of 1:0.6-0.8; The coupling agent is a ferulic acid bio-based silane modified coupling agent; The filler is hexamethyldisilazane modified hydrophobic fumed silica (HMDS hydrophobic white carbon black). The catalyst is a mixture of bismuth isooctanoate and zinc dioctanoate in a weight ratio of 1:1-1.5.

[0008] Preferably, the ferulic acid bio-based silane modified coupling agent is prepared by the following method: A1. Ferulic acid and long-chain fatty alcohol are dissolved in a first organic solvent and subjected to reflux esterification under the action of a first catalyst. During the reaction, the generated water is removed by a water separator. After the reaction, the ferulic acid long-chain alcohol ester is obtained by alkali washing, water washing, drying, concentration and column chromatography purification. A2. Dissolve ferulic acid long-chain alcohol ester and silane coupling agent in a second organic solvent, and carry out a ring-opening addition reaction in an inert gas under the action of a second catalyst; after the reaction is completed, the ferulic acid derivative grafted with the silane coupling agent is obtained after post-treatment.

[0009] Preferably, the long-chain fatty alcohol in step A1 is at least one of 2-octyldodecyl alcohol, isotridecyl alcohol, 3,7-dimethyloct-6-en-1-ol, and 16-methylheptadecyl-1-ol.

[0010] Preferably, in step A1, the molar ratio of ferulic acid to long-chain fatty alcohol is 1:2-3, the first catalyst is p-toluenesulfonic acid, the amount of p-toluenesulfonic acid is 0.8%-1.2% of the mass of ferulic acid, the first organic solvent is xylene, the reflux esterification reaction temperature is 130-140℃, and the reaction time is 12-14h.

[0011] Preferably, in step A2, the molar ratio of ferulic acid long-chain alcohol ester to silane coupling agent is 1:1.0-1.2, and the amount of the second catalyst is 0.8%-1.2% of the mass of ferulic acid long-chain alcohol ester.

[0012] Preferably, in step A2, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane; the second organic solvent is anhydrous toluene; the second catalyst is triethylamine; the ring-opening addition reaction is carried out under nitrogen protection at 80-100°C with stirring for 6-8 h; the post-treatment includes solvent removal by vacuum evaporation and column chromatography purification.

[0013] A method for preparing an environmentally friendly acidic silicone sealant for aquariums includes the following steps: B1. After mixing α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and hexamethyldisilazane-modified hydrophobic fumed silica, the mixture is heated and dehydrated under vacuum conditions, and then cooled to obtain the base material. B2. Add ferulic acid bio-based silane modified coupling agent to the base material and stir and mix under vacuum conditions to allow the coupling agent to react with the residual silanol groups on the surface of hexamethyldisilazane modified hydrophobic fumed silica. B3. Add the crosslinking agent to the system obtained in step B2, stir and mix, then add the catalyst and continue stirring until the mixture is uniform. B4. Discharge the product obtained in step B3 and fill and seal it to obtain the environmentally friendly acidic silicone sealant.

[0014] Preferably, the amount of α,ω-dihydroxypolydimethylsiloxane used is 100 parts by weight: In step B1, the amount of dimethyl silicone oil used is 15-25 parts by weight, and the amount of hexamethyldisilazane modified hydrophobic fumed silica used is 8-12 parts by weight. In step B2, the amount of ferulic acid bio-based silane modified coupling agent used is 1-3 parts by weight. In step B3, the amount of crosslinking agent is 6-10 parts by weight, and the amount of catalyst is 0.3-0.5 parts by weight.

[0015] Preferably, the mixing time in step B1 is 60-80 min, and the heating and dehydration temperature is 80-100℃; In step B2, the temperature is 80℃, and after addition, the mixture is stirred and mixed under vacuum at 60-80℃ for 30-60 minutes. The stirring and mixing time in step B3 is 10-15 min, and the stirring time continues for 30-60 min after adding the catalyst; In step B4, the filling is carried out under dry conditions, and the container is sealed immediately after filling.

[0016] Preferably, the environmentally friendly acidic silicone sealant prepared by the method is used in sealing the glass joints of aquariums.

[0017] In this invention, "parts by weight" refers to the relative weight ratio between the components, rather than a specific unit of weight. For example, when stating "100 parts by weight of α,ω-dihydroxypolydimethylsiloxane", it only means that the weight of this component is taken as the baseline 100, and the weight parts of other components are the weight ratios relative to this baseline.

[0018] Those skilled in the art should understand that the weight percentages are not fixed absolute amounts, but can be scaled up or down proportionally according to actual production scale, equipment capacity, or product requirements. As long as the relative weight ratios between the components remain constant, the technical effects of this invention can be achieved, and all such results fall within the scope of protection of this invention.

[0019] The beneficial effects of this invention are as follows: (I) Self-made ferulic acid-based bio-based silane coupling agent integrates multiple functions: The silane end of this ferulic acid-based bio-based silane coupling agent can covalently condense with the residual silanol groups on the surface of HMDS hydrophobic silica, achieving coupling function and thus enhancing the interfacial bonding between the filler and the matrix. Simultaneously, its ferulic acid backbone possesses natural UV absorption capabilities, effectively protecting the sealant from yellowing during long-term underwater service. The presence of phenolic hydroxyl groups and the conjugated system endows the coupling agent with natural antibacterial properties, helping to inhibit the adhesion of microorganisms to the sealant surface. Furthermore, the introduction of long-chain alcohols further improves the hydrophobicity and side-chain flexibility of the coupling agent, which is beneficial for enhancing the water resistance and mechanical flexibility of the sealant.

[0020] (ii) Using hydrophobic fillers instead of bactericides to achieve physical antifouling: This invention uses HMDS hydrophobic silica as a reinforcing filler. Its low surface energy can effectively reduce the adhesion of algae, bacteria and other microorganisms on the surface of the sealant, keeping the sealant clean in appearance. In addition, it can prevent mold and pollution without adding organic bactericides, avoiding the ecological risks of bactericide release to aquatic organisms and meeting the environmental safety requirements of aquariums.

[0021] (III) Optimize the feeding process to avoid hydrolysis of the coupling agent: In the preparation process of this invention, a ferulic acid-based bio-based silane coupling agent is first pre-mixed and reacted with HMDS hydrophobic silica under vacuum heating conditions. This allows the silane end of the coupling agent to preferentially condense with the residual silanol groups on the surface of the silica. An acidic crosslinking agent is then added in subsequent steps. This order of addition avoids direct contact between the coupling agent and the acidic crosslinking agent, preventing hydrolysis and self-polymerization, thus effectively ensuring the grafting efficiency of the coupling agent and the storage stability of the sealant. Detailed Implementation

[0022] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0023] Example 1 This embodiment provides a method for preparing an environmentally friendly acidic silicone sealant for aquariums, including the following steps: 1. Preparation of 2-octyldodecyl ferulic acid ester Ferulic acid and 2-octyldodecyl alcohol were dissolved in xylene at a molar ratio of 1:2.5. 1.0% (by mass) of p-toluenesulfonic acid was added as a catalyst. A water separator was installed, and the esterification reaction was carried out under nitrogen protection at 135°C under reflux for 13 hours. After the reaction was completed, the mixture was cooled to room temperature.

[0024] The reaction solution was slowly poured into a saturated sodium bicarbonate aqueous solution and stirred until no more bubbles escaped. The mixture was then separated. The organic phase was washed twice with saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using a gradient elution with petroleum ether:ethyl acetate ratios of 20:1, 8:1, and 4:1. The target fraction was collected, and the solvent was removed under reduced pressure to obtain ferulic acid-2-octyldodecyl ester.

[0025] 2. Preparation of bio-based silane coupling agents 2-Octyldodecyl ferulic acid ester and γ-glycidoxypropyltrimethoxysilane (KH-560) were dissolved in anhydrous toluene at a molar ratio of 1:1.1. Triethylamine (1.0% by weight of the ester) was added as a catalyst, and the mixture was stirred at 90°C for 7 hours under nitrogen protection. After the reaction was completed, the temperature was lowered, and toluene was removed by vacuum distillation below 40°C. Water was avoided throughout the post-treatment process.

[0026] The crude product was purified by silica gel column chromatography using a 200-300 mesh screen, followed by gradient elution with petroleum ether:ethyl acetate at ratios of 20:1 and 6:1. The target fraction was collected and concentrated under reduced pressure to obtain the bio-based silane coupling agent.

[0027] 3. Preparation of environmentally friendly acidic silicone sealant 100 parts of α,ω-dihydroxypolydimethylsiloxane, 20 parts of dimethyl silicone oil and 10 parts of hexamethyldisilazane-modified hydrophobic fumed silica were mixed and then heated at 90°C for 70 min under vacuum to remove water. After cooling, the base material was obtained.

[0028] Heat the base material to 80°C, add 2 parts of the above-mentioned bio-based silane coupling agent, and stir and mix at 70°C under vacuum for 45 minutes to allow the coupling agent to react with the residual silanol groups on the surface of the filler.

[0029] Eight parts of a crosslinking agent, which is a mixture of methyltriacetoxysilane and vinyltriacetoxysilane in a weight ratio of 1:0.7, were added to the obtained system. After stirring and mixing for 12.5 min, 0.4 parts of a catalyst, which is a mixture of bismuth isooctanoate and zinc dioctanoate in a weight ratio of 1:1.3, were added. Stirring was continued for 45 min until the mixture was homogeneous.

[0030] The obtained product is discharged, filled under dry conditions, and sealed immediately to obtain the environmentally friendly acidic silicone sealant.

[0031] Example 2 This embodiment provides a method for preparing an environmentally friendly acidic silicone sealant for aquariums, including the following steps: 1. Preparation of 2-octyldodecyl ferulic acid ester Ferulic acid and 2-octyldodecyl alcohol were dissolved in xylene at a molar ratio of 1:2.0. 0.8% (by mass) of p-toluenesulfonic acid was added as a catalyst. A water separator was installed, and the esterification reaction was carried out under nitrogen protection at 135°C under reflux for 13 hours. After the reaction was completed, the mixture was cooled to room temperature.

[0032] The reaction solution was slowly poured into a saturated sodium bicarbonate aqueous solution and stirred until no more bubbles escaped. The mixture was then separated. The organic phase was washed twice with saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using a gradient elution with petroleum ether:ethyl acetate ratios of 20:1, 8:1, and 4:1. The target fraction was collected, and the solvent was removed under reduced pressure to obtain ferulic acid-2-octyldodecyl ester.

[0033] 2. Preparation of bio-based silane coupling agents 2-Octyldodecanol ferulic acid ester and γ-glycidoxypropyltrimethoxysilane (KH-560) were dissolved in anhydrous toluene at a molar ratio of 1:1.0. Triethylamine (0.8% by mass of the ester) was added as a catalyst, and the mixture was stirred at 90°C for 7 hours under nitrogen protection. After the reaction was completed, the temperature was lowered, and toluene was removed by vacuum distillation below 40°C. Water was avoided throughout the post-treatment process.

[0034] The crude product was purified by silica gel column chromatography using a 200-300 mesh screen, followed by gradient elution with petroleum ether:ethyl acetate at ratios of 20:1 and 6:1. The target fraction was collected and concentrated under reduced pressure to obtain the bio-based silane coupling agent.

[0035] 3. Preparation of environmentally friendly acidic silicone sealant 100 parts of α,ω-dihydroxypolydimethylsiloxane, 15 parts of dimethyl silicone oil and 8 parts of hexamethyldisilazane-modified hydrophobic fumed silica were mixed and then heated at 90°C for 70 min under vacuum to remove water. After cooling, the base material was obtained.

[0036] Heat the base material to 80°C, add 1 part of the above-mentioned bio-based silane coupling agent, and stir and mix at 70°C for 45 minutes under vacuum conditions to allow the coupling agent to react with the residual silanol groups on the surface of the filler.

[0037] Add 6 parts of crosslinking agent to the obtained system. The crosslinking agent is a mixture of methyltriacetoxysilane and vinyltriacetoxysilane in a weight ratio of 1:0.6. After stirring and mixing for 12.5 min, add 0.3 parts of catalyst. The catalyst is a mixture of bismuth isooctanoate and zinc dioctanoate in a weight ratio of 1:1. Continue stirring for 45 min until the mixture is homogeneous.

[0038] The obtained product is discharged, filled under dry conditions, and sealed immediately to obtain the environmentally friendly acidic silicone sealant.

[0039] Example 3 This embodiment provides a method for preparing an environmentally friendly acidic silicone sealant for aquariums, including the following steps: 1. Preparation of 2-octyldodecyl ferulic acid ester Ferulic acid and 2-octyldodecyl alcohol were dissolved in xylene at a molar ratio of 1:3.0. 1.2% (by mass) of p-toluenesulfonic acid was added as a catalyst. A water separator was installed, and the esterification reaction was carried out under nitrogen protection at 135°C under reflux for 13 hours. After the reaction was completed, the mixture was cooled to room temperature.

[0040] The reaction solution was slowly poured into a saturated sodium bicarbonate aqueous solution and stirred until no more bubbles escaped. The mixture was then separated. The organic phase was washed twice with saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using a gradient elution with petroleum ether:ethyl acetate ratios of 20:1, 8:1, and 4:1. The target fraction was collected, and the solvent was removed under reduced pressure to obtain ferulic acid-2-octyldodecyl ester.

[0041] 2. Preparation of bio-based silane coupling agents 2-Octyldodecanol ferulic acid ester and γ-glycidoxypropyltrimethoxysilane (KH-560) were dissolved in anhydrous toluene at a molar ratio of 1:1.2. Triethylamine (1.2% by weight of the ester) was added as a catalyst, and the mixture was stirred at 90°C for 7 hours under nitrogen protection. After the reaction was completed, the temperature was lowered, and toluene was removed by vacuum distillation below 40°C. Water was avoided throughout the post-treatment process.

[0042] The crude product was purified by silica gel column chromatography using a 200-300 mesh screen, followed by gradient elution with petroleum ether:ethyl acetate at ratios of 20:1 and 6:1. The target fraction was collected and concentrated under reduced pressure to obtain the bio-based silane coupling agent.

[0043] 3. Preparation of environmentally friendly acidic silicone sealant 100 parts of α,ω-dihydroxypolydimethylsiloxane, 25 parts of dimethyl silicone oil and 12 parts of hexamethyldisilazane-modified hydrophobic fumed silica were mixed and then heated at 90°C for 70 min under vacuum to remove water. After cooling, the base material was obtained.

[0044] Heat the base material to 80°C, add 3 parts of the above-mentioned bio-based silane coupling agent, and stir and mix at 70°C for 45 minutes under vacuum conditions to allow the coupling agent to react with the residual silanol groups on the surface of the filler.

[0045] Add 10 parts of crosslinking agent to the obtained system. The crosslinking agent is a mixture of methyltriacetoxysilane and vinyltriacetoxysilane in a weight ratio of 1:0.8. After stirring and mixing for 12.5 min, add 0.5 parts of catalyst. The catalyst is a mixture of bismuth isooctanoate and zinc dioctanoate in a weight ratio of 1:1.5. Continue stirring for 45 min until the mixture is homogeneous.

[0046] The obtained product is discharged, filled under dry conditions, and sealed immediately to obtain the environmentally friendly acidic silicone sealant.

[0047] Example 4 This embodiment provides a method for preparing an environmentally friendly acidic silicone sealant for aquariums, including the following steps: 1. Preparation of 2-octyldodecyl ferulic acid ester Ferulic acid and 2-octyldodecyl alcohol were dissolved in xylene at a molar ratio of 1:2.5. 1.0% (by mass) of p-toluenesulfonic acid was added as a catalyst. A water separator was installed, and the esterification reaction was carried out under nitrogen protection at 130°C under reflux for 12 hours. After the reaction was completed, the mixture was cooled to room temperature.

[0048] The reaction solution was slowly poured into a saturated sodium bicarbonate aqueous solution and stirred until no more bubbles escaped. The mixture was then separated. The organic phase was washed twice with saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using a gradient elution with petroleum ether:ethyl acetate ratios of 20:1, 8:1, and 4:1. The target fraction was collected, and the solvent was removed under reduced pressure to obtain ferulic acid-2-octyldodecyl ester.

[0049] 2. Preparation of bio-based silane coupling agents 2-Octyldodecyl ferulic acid ester and γ-glycidoxypropyltrimethoxysilane (KH-560) were dissolved in anhydrous toluene at a molar ratio of 1:1.1. Triethylamine (1.0% by weight of the ester) was added as a catalyst, and the reaction was carried out under nitrogen protection at 80°C with stirring for 6 hours. After the reaction was completed, the temperature was lowered, and toluene was removed by vacuum distillation below 40°C. Water was avoided throughout the post-treatment process.

[0050] The crude product was purified by silica gel column chromatography using a 200-300 mesh screen, followed by gradient elution with petroleum ether:ethyl acetate at ratios of 20:1 and 6:1. The target fraction was collected and concentrated under reduced pressure to obtain the bio-based silane coupling agent.

[0051] 3. Preparation of environmentally friendly acidic silicone sealant 100 parts of α,ω-dihydroxypolydimethylsiloxane, 20 parts of dimethyl silicone oil and 10 parts of hexamethyldisilazane-modified hydrophobic fumed silica were mixed and then heated at 80°C for 60 min under vacuum to remove water. After cooling, the base material was obtained.

[0052] Heat the base material to 80°C, add 2 parts of the above-mentioned bio-based silane coupling agent, and stir and mix at 60°C under vacuum for 30 minutes to allow the coupling agent to react with the residual silanol groups on the surface of the filler.

[0053] Eight parts of a crosslinking agent, which is a mixture of methyltriacetoxysilane and vinyltriacetoxysilane in a weight ratio of 1:0.7, were added to the obtained system. After stirring and mixing for 10 min, 0.4 parts of a catalyst, which is a mixture of bismuth isooctanoate and zinc dioctanoate in a weight ratio of 1:1.3, were added. Stirring was continued for 30 min until the mixture was homogeneous.

[0054] The obtained product is discharged, filled under dry conditions, and sealed immediately to obtain the environmentally friendly acidic silicone sealant.

[0055] Example 5 This embodiment provides a method for preparing an environmentally friendly acidic silicone sealant for aquariums, including the following steps: 1. Preparation of 2-octyldodecyl ferulic acid ester Ferulic acid and 2-octyldodecyl alcohol were dissolved in xylene at a molar ratio of 1:2.5. 1.0% (by mass) of p-toluenesulfonic acid was added as a catalyst. A water separator was installed, and the esterification reaction was carried out under nitrogen protection at 140°C under reflux for 14 hours. After the reaction was completed, the mixture was cooled to room temperature.

[0056] The reaction solution was slowly poured into a saturated sodium bicarbonate aqueous solution and stirred until no more bubbles escaped. The mixture was then separated. The organic phase was washed twice with saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using a gradient elution with petroleum ether:ethyl acetate ratios of 20:1, 8:1, and 4:1. The target fraction was collected, and the solvent was removed under reduced pressure to obtain ferulic acid-2-octyldodecyl ester.

[0057] 2. Preparation of bio-based silane coupling agents 2-Octyldodecanol ferulic acid ester and γ-glycidoxypropyltrimethoxysilane (KH-560) were dissolved in anhydrous toluene at a molar ratio of 1:1.1. Triethylamine (1.0% by weight of the ester) was added as a catalyst, and the mixture was stirred at 100°C for 8 hours under nitrogen protection. After the reaction was completed, the temperature was lowered, and toluene was removed by vacuum distillation below 40°C. Water was avoided throughout the post-treatment process.

[0058] The crude product was purified by silica gel column chromatography using a 200-300 mesh screen, followed by gradient elution with petroleum ether:ethyl acetate at ratios of 20:1 and 6:1. The target fraction was collected and concentrated under reduced pressure to obtain the bio-based silane coupling agent.

[0059] 3. Preparation of environmentally friendly acidic silicone sealant 100 parts of α,ω-dihydroxypolydimethylsiloxane, 20 parts of dimethyl silicone oil and 10 parts of hexamethyldisilazane-modified hydrophobic fumed silica were mixed and then heated at 100°C for 80 min under vacuum to remove water. After cooling, the base material was obtained.

[0060] Heat the base material to 80°C, add 2 parts of the above-mentioned bio-based silane coupling agent, and stir and mix at 80°C for 60 minutes under vacuum conditions to allow the coupling agent to react with the residual silanol groups on the surface of the filler.

[0061] Eight parts of a crosslinking agent, which is a mixture of methyltriacetoxysilane and vinyltriacetoxysilane in a weight ratio of 1:0.7, were added to the obtained system. After stirring and mixing for 15 min, 0.4 parts of a catalyst, which is a mixture of bismuth isooctanoate and zinc dioctanoate in a weight ratio of 1:1.3, were added. Stirring was continued for 60 min until the mixture was homogeneous.

[0062] The obtained product is discharged, filled under dry conditions, and sealed immediately to obtain the environmentally friendly acidic silicone sealant.

[0063] Comparative Example 1 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that the molar ratio of ferulic acid to long-chain fatty alcohol in step 1 is 1:2.

[0064] Comparative Example 2 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that the molar ratio of ferulic acid to long-chain fatty alcohol in step 1 is 1:3.

[0065] Comparative Example 3 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that in step 2, the molar ratio of ferulic acid-2-octyldodecyl ester to KH-560 is 1:1.0.

[0066] Comparative Example 4 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that in step 2, the molar ratio of ferulic acid-2-octyldodecyl ester to KH-560 is 1:1.2.

[0067] Comparative Example 5 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that the weight ratio of MTAS to VTAS in step 3 is 1:0.6.

[0068] Comparative Example 6 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that the weight ratio of MTAS to VTAS in step 3 is 1:0.8.

[0069] Comparative Example 7 The comparative example follows the same process as Example 1 in preparing environmentally friendly acidic silicone sealant for aquariums, except that in step 1, the long-chain fatty alcohol (2-octyldodecyl alcohol) is replaced with an equimolar amount of short-chain alcohol (n-butanol).

[0070] Comparative Example 8 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that in step 3, the ferulic acid bio-based silane coupling agent is replaced with the ordinary silane coupling agent KH-550.

[0071] Comparative Example 9 The comparative example follows the same process as Example 1 in preparing environmentally friendly acidic silicone sealant for aquariums, except that in step 3, hexamethyldisilazane-modified hydrophobic fumed silica is used instead of ordinary fumed silica as the filler.

[0072] Comparative Example 10 The comparative example follows the same process as Example 1 in preparing the environmentally friendly acidic silicone sealant for aquariums, except that in step 2, the long-chain alcohol ester of ferulic acid that reacts with γ-glycidoxypropyltrimethoxysilane is replaced with free ferulic acid.

[0073] Performance testing Hydrophobic properties: The water contact angle was tested using a JC2000D contact angle meter. Five points were tested for each sample, and the average value was taken.

[0074] UV aging resistance test: Prepare a set of samples for heat aging treatment. Under standard conditions as required by GB16776-2005, place for 7 days. The test specimens are then kept in a forced-air drying oven at 90±2℃ for 21 days.

[0075] Yellowing resistance test: The adhesive strip cured at room temperature for 7 days was placed in an oven at 180℃ and baked for 12 hours. The degree of yellowing was observed and expressed as a yellowing level of 0-6. The higher the level, the more severe the yellowing.

[0076] Mechanical property testing: Two sets of specimens were prepared according to GB / T 13477.8-2003 and cured under standard test conditions for 28 days. After the curing period, the first set of specimens was directly subjected to tensile adhesion testing according to GB / T 13477.8-2003 to determine its mechanical properties under standard conditions. The second set of specimens was subjected to water-ultraviolet light treatment according to GB 16776-2005: using distilled water or deionized water as the medium, the test was conducted continuously for 300 hours. After the treatment, the specimens were placed under standard conditions for 2 hours, and then tensile tests were performed according to GB / T 13477.8-2003.

[0077] Anti-mildew performance: The anti-mildew effect was tested according to the test method specified in GB / T 1741-2020. The test data is shown in the table below:

[0078] By comparing the performance test data of Example 1 with those of Comparative Examples 1-6, it can be seen that Example 1 is significantly better than each of the comparative examples in key indicators such as mechanical strength, weather resistance, water resistance and mildew resistance, which fully demonstrates that the technical solution adopted in Example 1 is the preferred embodiment of the present invention.

[0079] Furthermore, performance test results showed that the hydrophobic and mechanical properties of Comparative Example 7 were significantly inferior to those of Example 1, suggesting that the long-chain alkyl group in the ferulic acid long-chain alcohol ester structure is a key functional segment. This long-chain alkyl group, acting as a hydrophobic side group, imparts excellent hydrophobic properties to the sealant; simultaneously, its flexible carbon chain acts as both an internal plasticizer and a physical crosslinking point in the polymer network, reducing stress concentration and thus improving the material's mechanical strength.

[0080] A comparison of the test data of Example 1 and Comparative Example 8 shows that Comparative Example 8 exhibits a significant decrease in aging resistance due to the absence of phenolic hydroxyl groups and conjugated double bonds. The underlying mechanism is speculated to be that the active hydrogen of the phenolic hydroxyl group can rapidly capture free radicals, while the conjugated double bonds can stabilize intermediates. The two work synergistically to endow the material with excellent antioxidant capacity. At the same time, the system itself possesses natural antibacterial activity, and its anti-mildew effect is significantly reduced after its absence. Furthermore, the conjugated double bonds have a strong absorption and shielding effect on ultraviolet rays, making the material more prone to photo-induced yellowing after their absence. Therefore, this structural unit is the key factor for Example 1 to possess aging resistance, anti-mildew, and anti-yellowing properties.

[0081] The performance comparison results between Example 1 and Comparative Example 9 show that Example 1, due to the use of hexamethyldisilazane-modified fumed silica, has a low surface energy, good compatibility with the matrix, and its hydrophobic and mildew-proof effects are significantly better than those of Comparative Example 9.

[0082] Comparing the data of Example 1 and Comparative Example 10, where the grafted ferulic acid in the Example 10 was replaced with free ferulic acid in the Comparative Example 10, it is evident that all properties of Comparative Example 10 are inferior to those of the Example 10. In the Comparative Example, the free ferulic acid is dispersed in the system through physical blending, relying solely on weak intermolecular interactions and lacking chemical bond anchoring. During curing and service, it is prone to migration, precipitation, and aggregation, leading to a decrease in mechanical properties such as tensile strength, adhesive strength, and elongation. Simultaneously, surface hydrophobicity and antimicrobial adhesion are also weakened. Therefore, chemical grafting of ferulic acid is crucial for achieving long-lasting antifungal properties and mechanical stability, which physical blending cannot easily replace.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An environmentally friendly acidic silicone sealant for aquariums, characterized in that, The product comprises α,ω-dihydroxypolydimethylsiloxane, and based on 100 parts of the α,ω-dihydroxypolydimethylsiloxane, it also comprises the following components by weight: 15-25 parts dimethyl silicone oil; 8-12 parts filler; 6-10 parts crosslinking agent; 1-3 parts modified coupling agent; 0.3-0.5 parts catalyst; The crosslinking agent is a mixture of methyltriacetoxysilane and vinyltriacetoxysilane in a weight ratio of 1:0.6-0.8; The coupling agent is a ferulic acid bio-based silane modified coupling agent; The filler is hexamethyldisilazane-modified hydrophobic fumed silica; The catalyst is a mixture of bismuth isooctanoate and zinc dioctanoate in a weight ratio of 1:1-1.

5.

2. The environmentally friendly acidic silicone sealant according to claim 1, characterized in that, The ferulic acid-based bio-based silane-modified coupling agent is prepared by the following method: A1. Ferulic acid and long-chain fatty alcohol are dissolved in a first organic solvent and subjected to reflux esterification under the action of a first catalyst. During the reaction, the generated water is removed by a water separator. After the reaction, the ferulic acid long-chain alcohol ester is obtained by alkali washing, water washing, drying, concentration and column chromatography purification. A2. Dissolve ferulic acid long-chain alcohol ester and silane coupling agent in a second organic solvent, and carry out a ring-opening addition reaction in an inert gas under the action of a second catalyst; after the reaction is completed, the ferulic acid derivative grafted with the silane coupling agent is obtained after post-treatment.

3. The environmentally friendly acidic silicone sealant according to claim 1, characterized in that, In step A1, the long-chain fatty alcohol is at least one of 2-octyldodecyl alcohol, isotridecyl alcohol, 3,7-dimethyloct-6-en-1-ol, and 16-methylheptadecyl-1-ol.

4. The environmentally friendly acidic silicone sealant according to claim 1, characterized in that, In step A1, the molar ratio of ferulic acid to long-chain fatty alcohol is 1:2-3, the first catalyst is p-toluenesulfonic acid, the amount of p-toluenesulfonic acid is 0.8%-1.2% of the mass of ferulic acid, the first organic solvent is xylene, the reflux esterification reaction temperature is 130-140℃, and the reaction time is 12-14h.

5. The environmentally friendly acidic silicone sealant according to claim 1, characterized in that, In step A2, the molar ratio of ferulic acid long-chain alcohol ester to silane coupling agent is 1:1.0-1.2, and the amount of the second catalyst is 0.8%-1.2% of the mass of ferulic acid long-chain alcohol ester.

6. The environmentally friendly acidic silicone sealant according to claim 1, characterized in that, In step A2, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane; the second organic solvent is anhydrous toluene; the second catalyst is triethylamine; the ring-opening addition reaction is carried out under nitrogen protection at 80-100℃ with stirring for 6-8 h; the post-treatment includes solvent removal by vacuum evaporation and column chromatography purification.

7. A method for preparing an environmentally friendly acidic silicone sealant for aquariums, characterized in that, Includes the following steps: B1. After mixing α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and hexamethyldisilazane-modified hydrophobic fumed silica, the mixture is heated and dehydrated under vacuum conditions, and then cooled to obtain the base material. B2. Add ferulic acid bio-based silane modified coupling agent to the base material and stir and mix under vacuum conditions to allow the coupling agent to react with the residual silanol groups on the surface of hexamethyldisilazane modified hydrophobic fumed silica. B3. Add the crosslinking agent to the system obtained in step B2, stir and mix, then add the catalyst and continue stirring until the mixture is uniform. B4. Discharge the product obtained in step B3 and fill and seal it to obtain the environmentally friendly acidic silicone sealant.

8. The method for preparing the environmentally friendly acidic silicone sealant according to claim 7, characterized in that, Based on 100 parts by weight of the α,ω-dihydroxypolydimethylsiloxane: In step B1, the amount of dimethyl silicone oil used is 15-25 parts by weight, and the amount of hexamethyldisilazane modified hydrophobic fumed silica used is 8-12 parts by weight. In step B2, the amount of ferulic acid bio-based silane modified coupling agent used is 1-3 parts by weight. In step B3, the amount of crosslinking agent is 6-10 parts by weight, and the amount of catalyst is 0.3-0.5 parts by weight.

9. The method for preparing the environmentally friendly acidic silicone sealant according to claim 7, characterized in that, The mixing time in step B1 is 60-80 min, and the heating and dehydration temperature is 80-100℃. In step B2, the temperature is 80℃, and after addition, the mixture is stirred and mixed under vacuum at 60-80℃ for 30-60 minutes. The stirring and mixing time in step B3 is 10-15 min, and the stirring time continues for 30-60 min after adding the catalyst; In step B4, the filling is carried out under dry conditions, and the container is sealed immediately after filling.

10. The application of an environmentally friendly acidic silicone sealant in sealing glass joints in aquariums, characterized in that... The sealant includes the environmentally friendly acidic silicone sealant according to any one of claims 1-6 or the environmentally friendly acidic silicone sealant prepared by the preparation method according to any one of claims 7-9.

Images