Condensation type adhesive silica gel capable of being rapidly and deeply cured and preparation method of condensation type adhesive silica gel

Abstract

The invention relates to condensation type bonding silica gel capable of being rapidly and deeply cured and a preparation method thereof, and belongs to the technical field of adhesives. The modified silicone sealant is obtained by curing the self-made curing unit, the modified filler and the alpha, omega-dihydroxy polydimethylsiloxane, the curing unit contains multiple functional groups including guanidyl, quaternary ammonium salt ions and oxime groups, the guanidyl has strong affinity to phosphate groups, nucleic acid, ATP and cell walls of bacteria can be collapsed, and the antibacterial activity of the bacteria can be improved. Meanwhile, guanidyl and quaternary ammonium salt ions can generate electrostatic interaction with negatively charged bacterial cell membranes, so that the silica gel has an antibacterial effect; the quaternary ammonium salt ion group can also form better interface bonding with the substrate of the silica gel, so that the bonding strength of the colloid is improved; the oximido group as an active group is subjected to condensation reaction with the terminal hydroxyl group, so that the surface drying time of the silicone sealant can be shortened, the oximido group has moderate polarity and is slightly influenced by temperature, the wettability of the filler can be improved, the reinforcing effect can be enhanced, and the silica gel can still be cured at low temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and in particular relates to a condensation-type adhesive silica gel capable of rapid and deep curing and a preparation method thereof. Background Art

[0002] Condensation-type adhesive silicones are widely used in fields such as construction and electronics due to their room-temperature curing and excellent adhesion. However, traditional condensation-type adhesive silicones have some shortcomings, prompting research to develop products that can cure quickly and deeply.

[0003] Condensation silicones cure using moisture from the air, resulting in rapid surface drying but slow deep-layer curing. This results in weak silicone strength over a short period of time, making it prone to wrinkling or damage when the substrate is moved, and degraded sealing performance. This makes them unable to meet the demands of rapid post-construction transportation in applications such as automotive manufacturing. In low-humidity environments or when thick adhesive is applied, condensation silicones can suffer from incomplete or even non-curing internally. While improvements can be made by adding hydrates, additives, or specific catalysts, these issues include yellowing of amino silicone oils and the potential for excessive heavy metals and corrosion of substrates with organotin catalysts. Single-component condensation silicone rubbers, such as dealcoholized silicones, offer advantages such as neutrality and non-corrosive properties, but their mechanical properties, such as tensile strength, are inferior to those of polyether-modified silane sealants and polyurethane sealants, limiting their application in some structural bonding applications. Simply adding reinforcing fillers such as fumed silica offers limited strength gains, necessitating new modification methods to enhance strength and toughness. Inherent flaws in silicone fillers also impact the overall performance of condensation silicone adhesives. In addition, in order to meet different application scenarios, silicone is also required to have better weather resistance, aging resistance and other properties, which can be achieved through modification.

[0004] The preparation of condensation-type adhesive silicone that can be quickly and deeply cured through modification can increase the curing speed, improve mechanical properties, enhance environmental adaptability, etc., which has important practical significance and market value.

[0005] Based on this, the present invention provides a condensation-type adhesive silica gel capable of rapid and deep curing and a preparation method thereof. Summary of the Invention

[0006] The object of the present invention is to provide a fast and deep curing condensation-type adhesive silica gel and a preparation method thereof, so as to solve the problems mentioned in the above background technology.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a condensation-type adhesive silica gel capable of rapid deep curing comprises the following steps: In the first step, 2-aminopyrimidine, N, N-diisopropylcarbodiimide, and tetrahydrofuran were mixed in a three-necked flask, equipped with a condenser and a thermometer, and magnetic stirring was turned on. The system temperature was raised to 55-65°C, reacted for 3 days, cooled to room temperature, and filtered to separate the precipitate, washed with ether, and dried to obtain an antibacterial monomer; In the second step, 1-chlorobutanone, antibacterial monomer and acetonitrile were added to a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, the system was heated to 50-60°C, reacted for 10-12 hours, cooled to room temperature, and then filtered to obtain a hygroscopic antibacterial agent; Step 3: Add the hygroscopic antibacterial agent, hydrogen peroxide, ammonia water, TS-1 titanium silicate molecular sieve and ethanol into a three-necked flask, install a condenser and a thermometer, turn on the magnetic stirring, heat the system to 70-80°C, react for 3-4 hours, cool to room temperature, and filter to obtain a solidified monomer; Step 4: Add the silane coupling agent and ethanol to a three-necked flask, install a condenser and a thermometer, turn on the magnetic stirring, heat the system to 25-35°C, react for 40-50 minutes, add fumed silica, heat the system to 60-70°C, react for 100-120 minutes, cool to room temperature, filter, wash with water, and dry to obtain a modified filler; Step 5: Add α, ω-dihydroxypolydimethylsiloxane and curing unit into a planetary stirred tank and stir under vacuum for 10 to 20 minutes, then add modified filler and stir for 25 to 35 minutes, finally add antioxidant and dibutyltin dilaurate and stir for 40 to 60 minutes, then discharge and fill to obtain modified silicone sealant.

[0008] Furthermore, in the first step, the mass ratio of 2-aminopyrimidine, N, N-diisopropylcarbodiimide and tetrahydrofuran is 9-11:15-19:45-50.

[0009] Furthermore, in the second step, the mass ratio of 1-chlorobutanone, antibacterial monomer and acetonitrile is 22-25:17-19:60-70.

[0010] Furthermore, in the third step, the mass fraction of hydrogen peroxide is 35-40%, and the mass fraction of ammonia water is 25-30%.

[0011] Furthermore, the mass ratio of the hygroscopic antibacterial agent, hydrogen peroxide, ammonia water, TS-1 titanium silicate molecular sieve and ethanol in the third step is 23-30:37-60:17-33:0.2-0.3:30-40.

[0012] Furthermore, the silane coupling agent in the fourth step is one of silane coupling agent KH580 and silane coupling agent KH590.

[0013] Furthermore, in the fourth step, the mass ratio of the silane coupling agent, ethanol and fumed silica is 24-28:30-40:6-7.

[0014] Furthermore, the antioxidant in the fifth step is one of antioxidant 1010, antioxidant 1070 or antioxidant 245.

[0015] Furthermore, in the fifth step, the mass ratio of α,ω-dihydroxypolydimethylsiloxane, curing unit, modified filler, antioxidant and dibutyltin dilaurate is 50-60:20-28:10-20:0.1-0.5:0.01-0.03.

[0016] Furthermore, in the fifth step, the vacuum condition is a vacuum degree of 0.095 to 0.1 MPa.

[0017] A fast and deep curing condensation type adhesive silica gel is prepared by any of the above preparation steps.

[0018] Beneficial effects of the present invention: The invention uses 2-aminopyrimidine and N, N-diisopropylcarbodiimide as raw materials for an addition reaction to obtain a guanidine-containing antibacterial monomer; uses 1-chlorobutanone and the antibacterial monomer as raw materials to carry out a quaternary ammonium salt reaction to obtain a hygroscopic antibacterial agent; then uses hydrogen peroxide, ammonia water and the hygroscopic antibacterial agent as raw materials and TS-1 titanium silicalite as a catalyst to carry out an oximation reaction to obtain a curing monomer; finally, the curing monomer, a modified filler obtained by grafting a silane coupling agent, and α, ω-dihydroxy polydimethylsiloxane are cured to obtain a modified silicone sealant.

[0019] The guanidine groups and quaternary ammonium ions contained in the curing unit of the present invention can both generate electrostatic interactions with negatively charged bacterial cell membranes and cell walls, destroying the integrity of the cell membranes and achieving an antibacterial effect. The guanidine groups have a strong affinity for phosphate groups and can form stable ionic and hydrogen bond networks, attacking and binding teichoic acid in peptidoglycan, phosphate groups in lipopolysaccharides, phosphate groups in ATP / ADP, and phosphate backbones in DNA / RNA, thereby disintegrating bacterial nucleic acids, ATP, and cell walls, and further enhancing the antibacterial effect of the silicone sealant. In addition, the quaternary ammonium ions have sites with permanent positive charges, and their cationic groups can form better interfacial bonds with the silicone sealant matrix, reducing filler agglomeration and improving colloid bonding strength. The hydrophilic groups can reduce the surface tension of the material, enhance the wetting ability of the substrate, promote coating spreading or adhesive penetration, and optimize the silicone curing performance.

[0020] The oxime group in the curing unit of the present invention acts as an active group to undergo a condensation reaction with the terminal hydroxyl group to release ketoxime, which can shorten the surface drying time of the silicone sealant. In a low-temperature environment, the curing activity of the oxime group is significantly higher than that of the traditional alkoxy system, which can avoid delayed curing of the silicone sealant. The oxime group chelate bond energy is stable and the activity of the nitroso radical is less affected by temperature, so the silicone sealant can still be cured at low temperatures. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions of the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection requested by this application.

[0022] The sources of all raw materials in the present invention are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0023] Example 1: A fast and deep curing condensation-type adhesive silica gel is prepared by the following steps.

[0024] In the first step, 9 g of 2-aminopyrimidine, 15 g of N, N-diisopropylcarbodiimide, and 45 g of tetrahydrofuran were mixed in a three-necked flask, equipped with a condenser and a thermometer, and magnetic stirring was turned on. The system temperature was raised to 65°C, reacted for 3 days, cooled to room temperature, and the precipitate was filtered and separated, washed with ether, and dried to obtain an antibacterial monomer; In the second step, 22g of 1-chlorobutanone, 17g of antibacterial monomer and 60g of acetonitrile were added to a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, the system was heated to 60°C, reacted for 10h, cooled to room temperature and filtered to obtain a hygroscopic antibacterial agent; Step 3: Add 23g of hygroscopic antibacterial agent, 37g of 35% by mass hydrogen peroxide, 17g of 28% by mass ammonia water, 0.2g of TS-1 titanium silicate molecular sieve and 30g of ethanol into a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, heat the system to 80°C, react for 3h, cool to room temperature and filter to obtain a solidified monomer; Step 4: Add 24 g of silane coupling agent KH580 and 30 g of ethanol into a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, heat the system to 35 ° C, react for 40 minutes, add 6 g of fumed silica, heat the system to 70 ° C, react for 100 minutes, cool to room temperature, filter, wash with water, and dry to obtain a modified filler; Step 5: Add 50g of α, ω-dihydroxypolydimethylsiloxane and 20g of curing monomer into a planetary stirred tank and stir at 0.095MP for 10min, then add 10g of modified filler and stir for 25min, finally add 0.1g of antioxidant 1010 and 0.01g of dibutyltin dilaurate and stir for 40min, then discharge and fill to obtain modified silicone sealant.

[0025] A fast and deep curing condensation type adhesive silica gel is prepared by the above preparation steps.

[0026] Example 2: A fast and deep curing condensation-type adhesive silica gel is prepared by the following steps.

[0027] In the first step, 10 g of 2-aminopyrimidine, 17 g of N, N-diisopropylcarbodiimide, and 48 g of tetrahydrofuran were mixed in a three-necked flask, equipped with a condenser and a thermometer, and magnetic stirring was turned on. The system temperature was raised to 60°C, reacted for 3 days, cooled to room temperature, and then filtered to separate the precipitate, washed with ether, and dried to obtain an antibacterial monomer; In the second step, 23.5 g of 1-chlorobutanone, 18 g of antibacterial monomer and 65 g of acetonitrile were added to a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, the system was heated to 55°C, reacted for 11 hours, cooled to room temperature and filtered to obtain a hygroscopic antibacterial agent; Step 3: Add 26.5 g of hygroscopic antibacterial agent, 48.5 g of 31.25% by mass hydrogen peroxide, 25 g of 26.5% by mass ammonia water, 0.25 g of TS-1 titanium silicate molecular sieve and 35 g of ethanol into a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, heat the system to 75 ° C, react for 3.5 hours, cool to room temperature, and filter to obtain a solidified monomer; Step 4: Add 26 g of silane coupling agent KH590 and 35 g of ethanol into a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, heat the system to 30 ° C, react for 45 minutes, add 6.5 g of fumed silica, heat the system to 65 ° C, react for 110 minutes, cool to room temperature, filter, wash with water, and dry to obtain a modified filler; Step 5: Add 55g of α, ω-dihydroxypolydimethylsiloxane and 24g of curing monomer into a planetary stirred tank and stir at 0.098MP for 10min, then add 15g of modified filler and stir for 30min, and finally add 0.3g of antioxidant 1070 and 0.03g of dibutyltin dilaurate and stir for 50min, then discharge and fill to obtain modified silicone sealant.

[0028] A fast and deep curing condensation type adhesive silica gel is prepared by the above preparation steps.

[0029] Example 3: A fast and deep curing condensation-type adhesive silica gel is prepared by the following steps.

[0030] In the first step, 11 g of 2-aminopyrimidine, 19 g of N, N-diisopropylcarbodiimide, and 50 g of tetrahydrofuran were mixed in a three-necked flask, equipped with a condenser and a thermometer, and magnetic stirring was turned on. The system temperature was raised to 55°C, reacted for 3 days, cooled to room temperature, and then filtered to separate the precipitate, washed with ether, and dried to obtain an antibacterial monomer; In the second step, 25g of 1-chlorobutanone, 19g of antibacterial monomer and 70g of acetonitrile were added to a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, the system was heated to 50°C, reacted for 12h, cooled to room temperature and then filtered to obtain a hygroscopic antibacterial agent; Step 3: Add 30g of hygroscopic antibacterial agent, 60g of 27.5% hydrogen peroxide, 33g of 25% ammonia water, 0.3g of TS-1 titanium silicate molecular sieve and 40g of ethanol into a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, heat the system to 70°C, react for 4h, cool to room temperature and filter to obtain a solidified monomer; Step 4: Add 28 g of silane coupling agent KH590 and 40 g of ethanol into a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, heat the system to 25 ° C, react for 50 minutes, add 7 g of fumed silica, heat the system to 60 ° C, react for 120 minutes, cool to room temperature, filter, wash with water, and dry to obtain a modified filler; Step 5: Add 60g of α, ω-dihydroxypolydimethylsiloxane and 28g of curing monomer into a planetary stirred tank and stir at 0.1MP for 20min, then add 20g of modified filler and stir for 35min, and finally add 0.5g of antioxidant 245 and 0.05g of dibutyltin dilaurate and stir for 60min, then discharge and fill to obtain modified silicone sealant.

[0031] A fast and deep curing condensation type adhesive silica gel is prepared by the above preparation steps.

[0032] Comparative Example 1 55 g of α, ω-dihydroxypolydimethylsiloxane and 24 g of curing monomer were added to a planetary stirred kettle and stirred at 0.098 MP for 10 minutes. Then, 15 g of fumed silica filler was added and stirred for 30 minutes. Finally, 0.3 g of antioxidant 1070 and 0.03 g of dibutyltin dilaurate were added and stirred for 50 minutes. The modified silicone sealant was discharged and filled.

[0033] Experimental Example 1 The silicone sealants in Examples 1 to 3 and Comparative Example 1 were respectively subjected to performance tests. The antibacterial properties of each group of silicone sealants were tested with reference to GB / T 1741-2020 "Determination of mildew resistance of paint films", and the mildew resistance grade of each group of silicone sealants was recorded; the curing performance of each group of silicone sealants was tested with reference to GB / T 14683-2017 "Silicone and modified silicone building sealants", and the tensile strength of each group of silicone sealants was recorded. The test results are shown in Table 1.

[0034] Table 1

[0035] It can be seen from Table 1 that compared with Comparative Example 1, the mildew resistance grade and tensile strength of Examples 1 to 3 are higher, indicating that the antibacterial performance and curing performance of Examples 1 to 3 are better than those of Comparative Example 1. Combined with Comparative Example 1, it can be seen that the modified silane crosslinker can effectively improve the antibacterial performance and curing performance of silicone sealant.

[0036] The above embodiments are merely intended to facilitate understanding of the methods and core concepts of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a fast and deep curing condensation-type adhesive silica gel, characterized in that: The following steps are involved: Preparation of the curing unit: an antibacterial monomer is obtained by an addition reaction between 2-aminopyrimidine and N, N-diisopropylcarbodiimide, a hygroscopic antibacterial agent is obtained by a quaternary ammonium salt reaction between 1-chlorobutanone and the antibacterial monomer, and a curing monomer is obtained by an oximation reaction between hydrogen peroxide, ammonia water, and the hygroscopic antibacterial agent; Preparation of modified silicone sealant: modified silica is grafted with a silane coupling agent to obtain a modified filler, and α, ω-dihydroxypolydimethylsiloxane, the modified filler, a curing unit, an antioxidant, and dibutyltin dilaurate are stirred under vacuum conditions to obtain the modified silicone sealant.

2. The method for preparing a fast deep curing condensation type adhesive silica gel according to claim 1, characterized in that: The mass ratio of 2-aminopyrimidine to N, N-diisopropylcarbodiimide is 9-11:15-19.

3. The method for preparing a fast deep curing condensation type adhesive silica gel according to claim 1, characterized in that: The mass ratio of 1-chlorobutanone to the antibacterial monomer is 22-25:17-19.

4. The method for preparing a fast and deep curing condensation-type adhesive silica gel according to claim 1, characterized in that: The mass fraction of hydrogen peroxide is 27.5-35%, and the mass fraction of ammonia water is 25-38%.

5. The method for preparing a fast deep curing condensation type adhesive silica gel according to claim 1, characterized in that: The mass ratio of the hygroscopic antibacterial agent, hydrogen peroxide and ammonia water is 23-30:37-60:17-33.

6. The method for preparing a fast and deep curing condensation-type adhesive silica gel according to claim 1, characterized in that: The mass ratio of the silane coupling agent to the fumed silica is 24-28:6-7.

7. The method for preparing a fast and deep curing condensation-type adhesive silica gel according to claim 1, characterized in that: The silane coupling agent is one of silane coupling agent KH580 and silane coupling agent KH590, and the antioxidant is one of antioxidant 1010, antioxidant 1070 and antioxidant 245.

8. The method for preparing a fast deep curing condensation type adhesive silica gel according to claim 1, characterized in that The mass ratio of α,ω-dihydroxypolydimethylsiloxane, curing unit, modified filler, antioxidant and dibutyltin dilaurate is 50-60:20-28:10-20:0.1-0.5:0.01-0.

03.

9. The method for preparing a fast and deep curing condensation-type adhesive silica gel according to claim 1, characterized in that: The vacuum condition is a vacuum degree of 0.095 to 0.1 MPa.

10. A fast and deep curing condensation type adhesive silica gel, characterized in that: The fast and deep curing condensation-type adhesive silica gel is prepared by the preparation method described in any one of claims 1 to 9.

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