High-strength optical-grade transparent dealcoholized organosilicon sealant and preparation method thereof

Abstract

The invention discloses a high-strength optical-grade transparent dealcoholized organosilicon sealant and a preparation method thereof. The dealcoholized organic silicon sealant is prepared from the following raw materials in parts by mass: 100 parts of vinyl-terminated polydimethylsiloxane, 30 to 50 parts of vinyl MQ silicon resin, 12 to 15 parts of single-ended hydrogen-containing trimethoxy polydimethylsiloxane, 0.06 to 0.18 part of platinum catalyst, 5 to 10 parts of dimethyl silicone oil, 3 to 10 parts of cross-linking agent, 2 to 5 parts of coupling agent and 0.5 to 1.5 parts of organic tin catalyst. The dealcoholized organosilicon sealant prepared by the invention has excellent mechanical properties and optical-grade light transmission, and can be cured at normal temperature.

Description

Technical Field

[0001] The present invention relates to the field of sealants, and in particular to a high-strength, optically transparent dealcoholized organosilicon sealant and a preparation method thereof. Background Art

[0002] In existing technology, dealcoholized silicone sealants are typically made from a base of hydroxyl-terminated polydimethylsiloxane or alkoxy-terminated polydimethylsiloxane, with appropriate amounts of a crosslinker and catalyst. To improve the mechanical properties of silicone sealants, reinforcing fillers such as calcium carbonate, silica, and organic montmorillonite are also added.

[0003] For example, Chinese patent publication number CN107118736A discloses a dealcoholized silicone sealant composition comprising alkoxy-terminated polydimethylsiloxane, white carbon black, an organotin catalyst, a plasticizer, a water scavenger, a tackifier, and a stabilizer. The addition of white carbon black to improve mechanical properties reduces the silicone sealant's transparency, preventing it from achieving optical-grade transparency and making it difficult to use in optical devices.

[0004] For example, Chinese patent publication number CN104945914A discloses an optically transparent liquid silicone rubber composition comprising vinyl-terminated polydimethylsiloxane, vinyl MQ silicone resin, methyl hydrogen MQ silicone resin, hydrogen-containing silicone oil, an inhibitor, and a platinum catalyst. This liquid silicone rubber has advantages such as high transparency and high resilience, but lacks adhesive properties and cannot be cured at room temperature.

[0005] In view of this, the present invention provides a high-strength, optically transparent dealcoholized organosilicon sealant and a preparation method thereof to solve the above problems. Summary of the Invention

[0006] In order to overcome the deficiencies of the above technologies, the present invention provides a high-strength, optically transparent dealcoholized organosilicon sealant which is viscous and can be cured at room temperature and has excellent mechanical properties after curing.

[0007] To achieve the above objectives, the present invention provides a high-strength, optically transparent dealcoholized silicone sealant, comprising the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 30-50 parts of vinyl MQ silicone resin, 12-15 parts of single-terminated hydrogen-containing trimethoxy polydimethylsiloxane, 0.06-0.18 parts of a platinum catalyst, 5-10 parts of dimethyl silicone oil, 3-10 parts of a cross-linking agent, 2-5 parts of a coupling agent, and 0.5-1.5 parts of an organotin catalyst.

[0008] Preferably, at 25° C., the viscosity of the vinyl-terminated polydimethylsiloxane is 10,000 to 50,000 mPa·s.

[0009] Preferably, the mass percentage of vinyl in the vinyl MQ silicone resin is 1.3% to 1.7%.

[0010] Preferably, the single-terminal hydrogenated trimethoxypolydimethylsiloxane is prepared by the addition reaction of hydrogenated polydimethylsiloxane and vinyltrimethoxysilane, and the molar ratio of Si-H of hydrogenated polydimethylsiloxane to the vinyl group of vinyltrimethoxysilane is 2:1.

[0011] Preferably, the platinum catalyst is a platinum (0)-divinyltetramethyldisiloxane complex.

[0012] Preferably, the platinum content in the platinum catalyst is 5000 ppm.

[0013] Preferably, the crosslinking agent is one or a combination of methyltrimethoxysilane, ethyltrimethoxysilane, methyl orthosilicate, methyltriethoxysilane, ethyl orthosilicate, ethyl silicate oligomer, and propyl orthosilicate.

[0014] Preferably, the coupling agent is one or a combination of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, and diethylaminomethyltriethoxysilane.

[0015] Preferably, the organic tin catalyst is one or a combination of dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate, and chelated tin.

[0016] To achieve the above object, the present invention further provides a method for preparing a high-strength, optically transparent dealcoholized organosilicon sealant, comprising the following steps:

[0017] Step 1: Add vinyl-terminated polydimethylsiloxane, ethylene MQ silicone resin, and platinum catalyst into a blender and stir evenly at room temperature; then add single-terminated hydrogen-containing trimethoxy polydimethylsiloxane and stir at room temperature for 5 to 15 minutes;

[0018] Step 2: Heat the mixture in the mixer to 100-120°C and react for 0.5-2h;

[0019] Step 3: After the reaction, the mixture in the mixer is cooled to below 50°C, and then dimethyl silicone oil is added and stirred for 10 to 20 minutes while the mixer is evacuated and nitrogen is circulated;

[0020] Step 4: Add the crosslinking agent, coupling agent, and organotin catalyst into a blender and mix them evenly to obtain an organosilicon sealant;

[0021] Step 5: Vacuum the mixer to degas the silicone sealant, and then press and package the material.

[0022] Preferably, the preparation steps of the single-end hydrogen-containing trimethoxy polydimethylsiloxane are as follows: add the end-hydrogen-containing polydimethylsiloxane and the platinum catalyst into a stirrer and stir evenly, heat to 60-80° C. under nitrogen protection, and then slowly add vinyltrimethoxysilane dropwise for 1 hour and react for 3-6 hours.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention modifies vinyl-terminated polydimethylsiloxane and vinyl MQ silicone resin with a single-terminated hydrogen-containing trimethoxy polydimethylsiloxane, resulting in the grafting of reactive methoxy groups onto the vinyl-terminated polydimethylsiloxane and vinyl MQ silicone resin. This, in conjunction with a crosslinking agent, a coupling agent, and an organotin catalyst, enables curing under ambient air conditions. Furthermore, during the dealcoholization condensation, crosslinking reactions between the components form a compact network structure, thereby improving the mechanical properties of the silicone sealant.

[0025] 2. Compared with the dealcoholized silicone sealant in the prior art, the silicone sealant of the present invention adds vinyl MQ silicone resin as a liquid reinforcing filler, which further improves the mechanical strength of the silicone sealant without affecting the transparency of the silicone sealant, so that the overall transparency of the silicone sealant can reach optical level. DETAILED DESCRIPTION

[0026] The following examples further illustrate the features of the present invention and other related features to facilitate understanding by those skilled in the art:

[0027] An embodiment of the present invention provides a high-strength, optically transparent dealcoholized silicone sealant, comprising the following raw materials in parts by mass: 100 parts of vinyl-terminated polydimethylsiloxane, 30-50 parts of vinyl MQ silicone resin, 12-15 parts of single-terminated hydrogen-containing trimethoxy polydimethylsiloxane, 0.06-0.18 parts of a platinum catalyst, 5-10 parts of dimethyl silicone oil, 3-10 parts of a cross-linking agent, 2-5 parts of a coupling agent, and 0.5-1.5 parts of an organotin catalyst.

[0028] In some embodiments, the viscosity of the vinyl-terminated polydimethylsiloxane at 25° C. is 10,000 to 50,000 mPa·s, indicating strong viscosity.

[0029] In some embodiments, the vinyl MQ silicone resin has a vinyl content of 1.3% to 1.7% by weight.

[0030] In some embodiments, the single-terminal hydrogen-containing trimethoxy polydimethylsiloxane is prepared by the addition reaction of terminal hydrogen-containing polydimethylsiloxane and vinyltrimethoxysilane, and the molar ratio of Si-H of the terminal hydrogen-containing polydimethylsiloxane to the vinyl group of vinyltrimethoxysilane is 2:1, so that the single-terminal hydrogen-containing trimethoxy polydimethylsiloxane can be generated as much as possible after the addition reaction of the terminal hydrogen-containing polydimethylsiloxane and vinyltrimethoxysilane.

[0031] In some embodiments, the platinum catalyst is used to catalyze the addition reaction of vinyl-terminated polydimethylsiloxane, vinyl MQ silicone resin, and single-terminated hydrogen-containing trimethoxy polydimethylsiloxane. The platinum catalyst is a platinum (0)-divinyltetramethyldisiloxane complex, which is highly compatible with vinyl-terminated polydimethylsiloxane, vinyl MQ silicone resin, and single-terminated hydrogen-containing trimethoxy polydimethylsiloxane.

[0032] In some embodiments, the platinum content in the platinum catalyst is 5000 ppm.

[0033] In some embodiments, the crosslinking agent is one or a combination of methyltrimethoxysilane, ethyltrimethoxysilane, methyl orthosilicate, methyltriethoxysilane, ethyl orthosilicate, ethyl silicate oligomer, and propyl orthosilicate. Under ambient air conditions, the silicone sealant undergoes dealcoholization condensation. The crosslinking agent is used to link the polymer molecules of the silicone sealant after dealcoholization condensation, thereby improving the mechanical properties of the silicone sealant.

[0034] In some embodiments, the coupling agent is one or a combination of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, and diethylaminomethyltriethoxysilane. The coupling agent is used to increase the adhesive properties of the silicone sealant and aid in curing and crosslinking.

[0035] In some embodiments, the organotin catalyst is one or a combination of dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate, and chelated tin. The organotin catalyst is used to catalyze the dealcoholization condensation reaction of methoxy groups and Si—H groups in the silicone sealant.

[0036] The embodiments of the present invention further provide a method for preparing a high-strength, optically transparent dealcoholized organosilicon sealant, comprising the following steps:

[0037] Step 1: Add 100 parts of vinyl-terminated polydimethylsiloxane, 30-50 parts of ethylene MQ silicone resin, and 0.06-0.18 parts of platinum catalyst into a blender and stir at room temperature for 10 minutes; then add 12-15 parts of single-terminated hydrogen-containing trimethoxy polydimethylsiloxane and stir at room temperature for 5-15 minutes.

[0038] Step 2: Heat the mixture in the mixer to 100-120°C and react for 0.5-2h. The vinyl groups of the vinyl polydimethylsiloxane and the vinyl MQ silicone resin react with the Si-H groups of the single-terminal hydrogen-containing trimethoxy polydimethylsiloxane to form an addition reaction, so that the vinyl-terminated polydimethylsiloxane and the vinyl MQ silicone resin are grafted with reactive methoxy groups. The polysiloxane and silicone resin grafted with methoxy groups can be cured in moisture.

[0039] Step 3: After the reaction, the mixture in the mixer is cooled to below 50° C., and then 5 to 10 parts of dimethyl silicone oil are added and stirred for 10 to 20 minutes. At the same time, the mixer is vacuumed and nitrogen is circulated to degas the mixture after the reaction.

[0040] Step 4: Add 3 to 10 parts of a cross-linking agent, 2 to 5 parts of a coupling agent, and 0.5 to 1.5 parts of an organotin catalyst into a blender and mix them evenly to obtain an organosilicon sealant.

[0041] Step 5: Vacuum the mixer to degas the silicone sealant, and then press and package the material.

[0042] In some embodiments, the single-terminated hydrogen-containing trimethoxy polydimethylsiloxane is prepared as follows: hydrogen-terminated polydimethylsiloxane and a platinum catalyst are added to a blender and stirred uniformly. The mixture is heated to 60-80°C under nitrogen protection, and then vinyltrimethoxysilane is slowly added dropwise for 1 hour and allowed to react for 3-6 hours. The resulting mixture is degassed at -99 kPa for 1-2 hours and cooled to room temperature to obtain the single-terminated hydrogen-containing trimethoxy polydimethylsiloxane.

[0043] Example 1

[0044] A method for preparing a high-strength, optically transparent dealcoholized organosilicon sealant comprises the following steps:

[0045] Step 1: Add 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 10,000 mP·s), 30 parts of ethylene MQ silicone resin (vinyl content 1.3%), and 0.06 parts of platinum catalyst to a planetary disperser and stir at room temperature for 10 minutes. Then, add 12 parts of single-terminated hydrogen-containing trimethoxy polydimethylsiloxane and stir at room temperature for 10 minutes.

[0046] Step 2: Heat the mixture in the planetary disperser to 100-120°C and react for 1 hour.

[0047] Step 3: After the reaction, the mixture in the planetary disperser is cooled to below 50°C, and then 5 parts of dimethyl silicone oil are added and stirred for 15 minutes. At the same time, the planetary disperser is vacuumed and nitrogen is circulated twice.

[0048] Step 4: Add 3 parts of ethyl orthosilicate, 2 parts of aminopropyltriethoxysilane, and 0.5 parts of dibutyltin dilaurate into a planetary disperser and stir for 5 minutes to obtain a silicone sealant.

[0049] Step 5: Evacuate the planetary disperser to degas the silicone sealant, and then press and package it.

[0050] Examples 2-4 and Comparative Examples 1-2 were prepared by changing the raw material formula according to Table 1 and following the preparation method of Example 1 to obtain the silicone sealants of Examples 2-4 and Comparative Examples 1-2. In Comparative Example 2, hydrophobic fumed silica was added after the dimethyl silicone oil and stirred evenly.

[0051] Table 1 Formulas of Examples 1 to 4 and Comparative Examples 1 to 2

[0052]

[0053] The organic silicone sealants prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to the following tests.

[0054] 1. Determine the surface drying time of silicone sealant according to GB / T13477.5 standard.

[0055] 2. Determine the Shore hardness of silicone sealant according to GB / T531.1-2008 standard.

[0056] 3. Determine the extrusion speed of silicone sealant according to GB / T13477.4.1-2017 standard.

[0057] 4. Determine the tensile strength and elongation at break of silicone sealant according to GB / T528-2009 standard.

[0058] 5. Determine the light transmittance of silicone sealant according to GB / T2410-2008 standard.

[0059] Table 2 Test results of Examples 1 to 4 and Comparative Examples 1 to 2

[0060]

[0061] (1) It can be seen from the data in Table 2 that the hardness, tensile strength and elongation at break of the silicone sealants of Examples 1 to 4 are all better than those of Comparative Example 1. This is because the vinyl MQ silicone resin is added to the silicone sealant. The vinyl MQ silicone resin forms a three-dimensional network structure in the silicone sealant, which plays an effective reinforcing role and enhances the mechanical properties of the silicone sealant.

[0062] (2) The light transmittance of the silicone sealants in Examples 1-4 was superior to that in Comparative Example 2. This was because, in Comparative Example 2, the addition of hydrophobic fumed silica significantly reduced the light transmittance of the silicone sealant in order to improve its mechanical properties. In contrast, Examples 1-4 used a vinyl MQ silicone resin silicone sealant, which not only ensured the silicone sealant had good mechanical properties but also achieved optical-grade light transmittance.

[0063] (3) Comparison of Examples 1 and 2 shows that while vinyl MQ silicone resin can improve the mechanical properties of silicone sealants, the amount of vinyl MQ silicone resin used has different effects on the hardness, tensile strength, and elasticity (elongation at break) of the silicone sealants. In the silicone sealant formulations of the present invention, a higher mass fraction of vinyl MQ silicone resin results in improved hardness and tensile strength, but a slight decrease in elasticity.

[0064] (4) From the comparison of Examples 1 to 4, it can be seen that the more cross-linking agent is used in the silicone sealant, the better the hardness and tensile strength of the silicone sealant, while the elasticity will decrease slightly. This is because the cross-linking agent connects the polymer molecules after dealcoholization condensation of the silicone sealant, which can improve the hardness and tensile strength of the silicone sealant.

[0065] (5) The tack-free rate of the silicone sealant in Example 1 is faster than that in Example 2. This is because the increased amounts of vinyl MQ silicone resin and single-terminal hydrogen-containing trimethoxypolydimethylsiloxane in the silicone sealant increase the dealcoholization time of the silicone sealant, slowing the curing rate of the silicone sealant. Furthermore, a comparison of Examples 1 to 4 shows that the tack-free rate of the silicone sealant is also related to the amount of organotin catalyst used, with the magnitude of the tack-free rate being positively correlated with the amount of organotin catalyst used.

[0066] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, is also included in the patent protection scope of the present invention.

Claims

1. A high-strength, optically transparent dealcoholized silicone sealant, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane, 30-50 parts of vinyl MQ silicone resin, 12-15 parts of single-terminated hydrogen-containing trimethoxy polydimethylsiloxane, 0.06-0.18 parts of platinum catalyst, 5-10 parts of dimethyl silicone oil, 3-10 parts of crosslinking agent, 2-5 parts of coupling agent and 0.5-1.5 parts of organic tin catalyst.

2. A high-strength, optically transparent dealcoholized silicone sealant according to claim 1, characterized in that: At 25° C., the viscosity of the vinyl-terminated polydimethylsiloxane is 10000 to 50000 mPa·s.

3. A high-strength, optically transparent dealcoholized silicone sealant according to claim 1, characterized in that: The mass percentage of vinyl in the vinyl MQ silicone resin is 1.3% to 1.7%.

4. A high-strength, optically transparent dealcoholized silicone sealant according to claim 1, characterized in that: The single-terminal hydrogen-containing trimethoxy polydimethylsiloxane is prepared by addition reaction of terminal hydrogen-containing polydimethylsiloxane and vinyl trimethoxysilane, and the molar ratio of Si-H of the terminal hydrogen-containing polydimethylsiloxane to the vinyl group of vinyl trimethoxysilane is 2:

1.

5. The high-strength, optically transparent dealcoholized silicone sealant according to claim 1, characterized in that: The platinum catalyst is a platinum (0)-divinyltetramethyldisiloxane complex; the platinum content in the platinum catalyst is 5000 ppm.

6. A high-strength, optically transparent dealcoholized silicone sealant according to claim 1, characterized in that: The crosslinking agent is one or a combination of methyltrimethoxysilane, ethyltrimethoxysilane, methyl orthosilicate, methyltriethoxysilane, ethyl orthosilicate, ethyl silicate oligomer, and propyl orthosilicate.

7. A high-strength, optically transparent dealcoholized silicone sealant according to claim 1, characterized in that: The coupling agent is one or a combination of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, and diethylaminomethyltriethoxysilane.

8. The high-strength, optically transparent dealcoholized silicone sealant according to claim 1, characterized in that: The organic tin catalyst is one or a combination of dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate, and chelated tin.

9. A method for preparing a high-strength, optically transparent dealcoholized organic silicon sealant as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Add vinyl-terminated polydimethylsiloxane, ethylene MQ silicone resin, and platinum catalyst into a mixer and stir evenly at room temperature; then add single-terminated hydrogen-containing trimethoxy polydimethylsiloxane and stir at room temperature for 5 to 15 minutes; Step 2: Heat the mixture in the mixer to 100-120°C and react for 0.5-2h; Step 3: After the reaction, the mixture in the mixer is cooled to below 50°C, and then dimethyl silicone oil is added and stirred for 10 to 20 minutes, while the mixer is evacuated and nitrogen is circulated; Step 4: Add the crosslinking agent, coupling agent and organotin catalyst into a mixer and stir evenly to obtain an organosilicon sealant; Step 5: Evacuate the mixer to degas the silicone sealant, and then press and package it.

10. The method for preparing a high-strength, optically transparent dealcoholized organic silicon sealant according to claim 9, characterized in that: The single-terminal hydrogen-containing trimethoxy polydimethylsiloxane preparation steps are as follows: add the terminal hydrogen-containing polydimethylsiloxane and the platinum catalyst into a stirrer and stir evenly, heat to 60-80° C. under nitrogen protection, then slowly drop vinyl trimethoxy silane, the drop time is 1 hour, and react for 3-6 hours.

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