Silicone sealant not prone to discoloration and preparation method thereof

Abstract

The invention provides a silicone sealant not prone to discoloration and a preparation method thereof, and relates to the technical field of silicone sealants. The silicone sealant is prepared from the following components in parts by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 70 to 130 parts of filler, 0 to 20 parts of dimethyl silicone oil, 5 to 12 parts of cross-linking agent, 1 to 3 parts of coupling agent oligomer, 0.5 to 3 parts of epoxy coupling agent and 0.01 to 0.5 part of catalyst. The customized amino coupling agent oligomer with a specific structure is adopted, the formula is optimized, and the 107 glue, the filler and the like are matched in a proper proportion, so that the optimal effect can be achieved. According to the silicone sealant, the defects that an existing silicone sealant is poor in high-temperature tensile cohesiveness and prone to discoloring at high temperature can be overcome, discoloring is not prone to occurring, the high-temperature cohesiveness is good, particularly, the discoloring phenomenon in a high-temperature application scene is obviously improved, and the high requirements of special buildings, automobiles, electronic appliances and other specific application occasions are met.

Description

Technical Field

[0001] The invention relates to the technical field of silicone sealants, and in particular to a silicone sealant that is not prone to discoloration and a preparation method thereof. Background Art

[0002] Silicone sealant is a sealant with excellent bonding performance, high mechanical strength, high elongation, UV resistance, ozone resistance, weathering resistance, electrical insulation, etc. At the same time, it has good bonding applicability and can be bonded to most materials, so it has great application value and a wide range of applications, such as construction, electronics and electrical fields. However, silicone sealant is prone to discoloration after long-term use, especially under long-term sunlight and high temperature.

[0003] The discoloration of silicone sealant generally comes from amino-containing silane coupling agents such as KH550 and KH792, which are easy to discolor. Amino-containing silane coupling agents are necessary in silicone sealants, otherwise the adhesion will be significantly affected.

[0004] For example, patent application number CN200910066244 discloses that the anti-yellowing effect is improved by adding an anti-yellowing agent that is at least one of an ultraviolet absorber, an antioxidant or a light stabilizer. CN201410510343 improves the weather resistance of the sealant by adding a synergistic effect of a composite anti-yellowing agent. CN201711086800 achieves the effect of yellowing resistance and mildew resistance by adding a compound of a bactericide and a preservative. CN201911276618 achieves the effect of anti-yellowing by designing an aging filler with a special structure to absorb ultraviolet light and emit blue fluorescence, thereby compensating for the visual yellowing effect and achieving the anti-yellowing effect.

[0005] However, the above existing patented technologies all achieve the purpose of anti-yellowing by adding additives such as ultraviolet absorbers, antioxidants, etc. or adding light stabilizers and mildew inhibitors. Moreover, the above additives are generally organic macromolecules, which have the problem of poor compatibility with the silicone sealant system.

[0006] Patent application number CN201410044556 discloses a method for testing yellowing at high temperatures, which is aging at 100°C for 48 hours. The high-temperature treatment method in this technology has a low temperature and a short time, and does not pay attention to the long-term color stability at higher temperatures. In addition, the tensile bonding strength of silicone sealants at high temperatures is low and cannot meet specific requirements. At the same time, in a high temperature environment, silicone sealants change color more quickly.

[0007] In summary, the prior art lacks a solution that does not change color and maintains tensile adhesion for a long time in high-temperature application scenarios.

[0008] Based on the above problems, this patent proposes a silicone sealant that is not easy to change color, especially not change color at high temperatures, and has high temperature resistant adhesion and a preparation method thereof. Summary of the invention

[0009] The invention provides a silicone sealant that is not easy to change color and a preparation method thereof, and aims to solve the shortcomings of the existing silicone sealant, that is, poor high-temperature tensile adhesion and easy color change at high temperatures.

[0010] In order to achieve the above-mentioned purpose, the embodiment of the present invention provides a silicone sealant that is not easy to change color and a preparation method thereof. The present invention adopts a customized amino coupling agent oligomer with a specific structure, optimizes the formula, and matches 107 glue, filler, etc. in an appropriate proportion to achieve the best effect. The present invention can improve the shortcomings of the existing silicone sealant, such as poor high-temperature tensile adhesion and easy discoloration at high temperatures, and achieves the advantages of not easy to change color and good high-temperature adhesion, especially the discoloration phenomenon in high-temperature application scenarios is significantly improved, meeting the high requirements in special applications such as special buildings, automobiles, and electronic appliances.

[0011] An embodiment of the present invention provides a silicone sealant that is not easy to change color, which comprises the following components in parts by weight:

[0012]

[0013] Preferably, the hydroxyl-terminated polydimethylsiloxane has a viscosity of 3000 to 100000 mPa·s at 25°C.

[0014] Preferably, the filler is nano-active calcium carbonate with a particle size of 80±20 nm and a cubic crystal form.

[0015] Preferably, the dimethyl silicone oil has a viscosity of 100 to 1000 mPa·s at 25°C.

[0016] Preferably, the crosslinking agent is selected from at least two of phenyltributylacetoximine silane, methyltributylacetoximine silane and tetrabutylketoxime silane.

[0017] Preferably, the coupling agent oligomer has the following general formula:

[0018]

[0019] Among them, R1 is methyl, ethyl or propyl; R2 is an alkyl group with 5 to 20 carbon atoms; R3 is methyl or ethyl; X is γ-aminopropyl, N-(β-aminoethyl)-γ-aminopropyl) or 3-(diethylenetriamine)propyl; and n is 3 to 9.

[0020] Preferably, in the coupling agent oligomer, X is γ-aminopropyl, R2 is an alkyl group having 5 to 20 carbon atoms, and further, R2 is an alkyl group having 7 to 20 carbon atoms and containing phenyl groups; or, in the coupling agent oligomer, X is N-(β-aminoethyl)-γ-aminopropyl), R2 is an alkyl group having 7 to 20 carbon atoms, and further, R2 is an alkyl group having 9 to 20 carbon atoms, and further, R2 is an alkyl group having 9 to 20 carbon atoms and containing phenyl groups; or, in the coupling agent oligomer, X is 3-(diethylenetriamine)propyl, R2 is an alkyl group having 11 to 20 carbon atoms, and further, R2 is an alkyl group having 11 to 20 carbon atoms and containing phenyl groups.

[0021] Preferably, the epoxy coupling agent is at least one of γ-glycidyloxypropyltrimethoxysilane, epoxycyclohexylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysiloxane.

[0022] Preferably, the catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin dioctoate.

[0023] Based on a general concept of the invention, an embodiment of the present invention provides a method for preparing the above-mentioned silicone sealant that is not easy to change color, comprising the following steps:

[0024] S1: According to the proportion, the end-hydroxyl-terminated polydimethylsiloxane, filler and dimethyl silicone oil are stirred evenly, and vacuum dehydrated for 2 to 4 hours at a dehydration temperature of 90 to 140° C. and a vacuum degree of -0.09 to 0.1 MPa, and cooled to room temperature to obtain a base material;

[0025] S2: Add the base material, crosslinking agent, coupling agent oligomer, epoxy coupling agent and catalyst into a high-speed planetary mixer according to the proportion, and stir under vacuum at a vacuum degree of -0.075 to 0.095 MPa to obtain the product.

[0026] The above scheme of the present invention has the following beneficial effects:

[0027] (1) The present invention uses a unique amino coupling agent oligomer, which can greatly reduce the discoloration of amino groups due to its special structure - the long-chain alkane structure next to the aminosilane in the alternating copolymer structure. Furthermore, the branched structure of the long-chain alkane containing phenyl groups significantly improves its high temperature resistance and is less prone to discoloration, especially at high temperatures, it performs better than silicone sealants using aminosilanes such as KH550 and KH792 as coupling agents.

[0028] (2) The amino coupling agent oligomer of the present invention is still an organosilicon structure, and has good compatibility with the silicone adhesive system, and the anti-discoloration effect of the sealant is more durable and stable. At the same time, because its oligomer structure contains more reactive groups, its adhesion is also significantly improved, especially the tensile adhesion in a high temperature environment is better maintained. Furthermore, the tensile adhesion of di- and tri-aminosilane oligomers is better, because the coupling agent has a longer molecular chain, more amino groups, and contains both primary and secondary amine groups in the molecular structure. DETAILED DESCRIPTION

[0029] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, they are described in detail below in conjunction with specific embodiments.

[0030] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0032] In view of the existing problems, the present invention provides a silicone sealant that is not easy to change color, which comprises the following components by weight:

[0033]

[0034] Preferably, the hydroxyl-terminated polydimethylsiloxane has a viscosity of 3000 to 100000 mPa·s at 25°C.

[0035] Preferably, the filler is nano-active calcium carbonate with a particle size of 80±20 nm and a cubic crystal form.

[0036] Preferably, the dimethyl silicone oil has a viscosity of 100 to 1000 mPa·s at 25°C.

[0037] Preferably, the crosslinking agent is selected from at least two of phenyltributylacetoximine silane, methyltributylacetoximine silane and tetrabutylketoxime silane.

[0038] Preferably, the coupling agent oligomer has the following general formula:

[0039]

[0040] Among them, R1 is methyl, ethyl or propyl; R2 is an alkyl group with 5 to 20 carbon atoms; R3 is methyl or ethyl; X is γ-aminopropyl, N-(β-aminoethyl)-γ-aminopropyl) or 3-(diethylenetriamine)propyl; and n is 3 to 9.

[0041] Preferably, in the coupling agent oligomer, X is γ-aminopropyl, R2 is an alkyl group having 5 to 20 carbon atoms, and further, R2 is an alkyl group having 7 to 20 carbon atoms and containing phenyl groups; or, in the coupling agent oligomer, X is N-(β-aminoethyl)-γ-aminopropyl), R2 is an alkyl group having 7 to 20 carbon atoms, and further, R2 is an alkyl group having 9 to 20 carbon atoms, and further, R2 is an alkyl group having 9 to 20 carbon atoms and containing phenyl groups; or, in the coupling agent oligomer, X is 3-(diethylenetriamine)propyl, R2 is an alkyl group having 11 to 20 carbon atoms, and further, R2 is an alkyl group having 11 to 20 carbon atoms and containing phenyl groups.

[0042] Preferably, the epoxy coupling agent is at least one of γ-glycidyloxypropyltrimethoxysilane, epoxycyclohexylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysiloxane.

[0043] Preferably, the catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate, and dibutyltin dioctoate.

[0044] Based on a general concept of the invention, an embodiment of the present invention provides a method for preparing the above-mentioned silicone sealant that is not easy to change color, comprising the following steps:

[0045] S1: According to the proportion, the end-hydroxyl-terminated polydimethylsiloxane, filler and dimethyl silicone oil are stirred evenly, and vacuum dehydrated for 2 to 4 hours at a dehydration temperature of 90 to 140° C. and a vacuum degree of -0.09 to 0.1 MPa, and cooled to room temperature to obtain a base material;

[0046] S2: Add the base material, crosslinking agent, coupling agent oligomer, epoxy coupling agent and catalyst into a high-speed planetary mixer according to the proportion, and stir under vacuum at a vacuum degree of -0.075 to 0.095 MPa to obtain the product.

[0047] The coupling agent oligomers in the following examples are customized by Shandong Sike New Materials Co., Ltd. The following is a detailed description through specific examples.

[0048] Example 1

[0049] This embodiment provides a method for preparing a silicone sealant that is not easy to change color, comprising the following steps:

[0050] (1) 100 parts of 50000 mPa·s hydroxyl-terminated polydimethylsiloxane and 70 parts of nano calcium carbonate were stirred evenly, vacuum-dehydrated for 3 hours at a dehydration temperature of 100° C. and a vacuum degree of -0.095 MPa, and cooled to room temperature to obtain a base material;

[0051] (2) Add the above base material, 6 parts of methyltributylacetonato silane, 3 parts of phenyltributylacetonato silane, 2.5 parts of a customized coupling agent oligomer (R1 is methyl; R2 is heptyl; R3 is ethyl; X is N-(β-aminoethyl)-γ-aminopropyl); n=3), 1 part of γ-glycidyloxypropyltriethoxysilane, and 0.1 part of dibutyltin dioctoate into a high-speed planetary mixer, and stir under a vacuum degree of -0.085 MPa to obtain the product.

[0052] Example 2

[0053] This embodiment provides a method for preparing a silicone sealant that is not easy to change color, comprising the following steps:

[0054] (1) 100 parts of 10000 mPa·s hydroxyl-terminated polydimethylsiloxane, 90 parts of nano calcium carbonate, and 5 parts of dimethyl silicone oil were stirred evenly, and vacuum dehydrated for 2 hours at a dehydration temperature of 120° C. and a vacuum degree of -0.090 MPa. After cooling to room temperature, a base material was obtained;

[0055] (2) Add the above base material, 7 parts of methyltributylacetonato silane, 1.5 parts of phenyltributylacetonato silane, 3 parts of a customized coupling agent oligomer (R1 is propyl; R2 is dodecyl; R3 is methyl; X is 3-(diethylenetriamine)propyl; n=5), 1.2 parts of epoxycyclohexylmethyldimethoxysilane, and 0.5 parts of dibutyltin dilaurate into a high-speed planetary mixer, and stir under a vacuum degree of -0.095 MPa to obtain the product.

[0056] Example 3

[0057] This embodiment provides a method for preparing a silicone sealant that is not easy to change color, comprising the following steps:

[0058] (1) 100 parts of 80000 mPa·s hydroxyl-terminated polydimethylsiloxane, 100 parts of nano calcium carbonate, and 8 parts of dimethyl silicone oil were uniformly stirred, vacuum-dehydrated for 4 hours at a dehydration temperature of 140° C. and a vacuum degree of -0.1 MPa, and cooled to room temperature to obtain a base material;

[0059] (2) Add the above base material, 8 parts of methyltributylacetonato silane, 2 parts of tetrabutylketoxime silane, 2.8 parts of a customized coupling agent oligomer (R1 is methyl; R2 is a linear long-chain alkyl group with 19 carbon atoms; R3 is methyl; X is γ-aminopropyl; n=7), 1 part of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 0.3 parts of dibutyltin dilaurate into a high-speed planetary mixer, and stir under vacuum at a vacuum degree of -0.088 MPa to obtain the product.

[0060] Example 4

[0061] This embodiment provides a method for preparing a silicone sealant that is not easy to change color, comprising the following steps:

[0062] (1) 100 parts of 50000 mPa·s hydroxyl-terminated polydimethylsiloxane, 110 parts of nano calcium carbonate, and 10 parts of dimethyl silicone oil were uniformly stirred, vacuum-dehydrated for 3 hours at a dehydration temperature of 130° C. and a vacuum degree of -0.096 MPa, and cooled to room temperature to obtain a base material;

[0063] (2) Add the above base material, 4 parts of methyltributylacetonato silane, 4 parts of phenyltributylacetonato silane, 2.5 parts of a customized coupling agent oligomer (R1 is ethyl; R2 is phenylnonyl; R3 is methyl; X is 3-(diethylenetriamine)propyl; n=6), 0.8 parts of γ-glycidyloxypropyltrimethoxysilane, and 0.2 parts of dibutyltin dilaurate into a high-speed planetary mixer, and stir under a vacuum degree of -0.093 MPa to obtain the product.

[0064] Example 5

[0065] This embodiment provides a method for preparing a silicone sealant that is not easy to change color, comprising the following steps:

[0066] (1) 100 parts of 100000 mPa·s hydroxyl-terminated polydimethylsiloxane, 120 parts of nano calcium carbonate, and 16 parts of dimethyl silicone oil were uniformly stirred, vacuum-dehydrated for 3 hours at a dehydration temperature of 135° C. and a vacuum degree of −0.098 MPa, and cooled to room temperature to obtain a base material;

[0067] (2) Add the above base material, 9 parts of methyltributylacetonato silane, 3 parts of tetrabutylketoxime silane, 0.5 parts of a customized coupling agent oligomer (R1 is methyl; R2 is phenylpentyl; R3 is ethyl; X is γ-aminopropyl; n=9), 2 parts of γ-glycidyloxypropyltrimethoxysilane, and 0.01 parts of dibutyltin diacetate into a high-speed planetary mixer, and stir under a vacuum degree of -0.090 MPa to obtain the product.

[0068] Example 6

[0069] This embodiment provides a method for preparing a silicone sealant that is not easy to change color, comprising the following steps:

[0070] (1) 100 parts of 20000 mPa·s hydroxyl-terminated polydimethylsiloxane, 130 parts of nano calcium carbonate, and 20 parts of dimethyl silicone oil were stirred uniformly, and vacuum dehydrated for 3.5 hours at a dehydration temperature of 125° C. and a vacuum degree of -0.093 MPa. After cooling to room temperature, a base material was obtained;

[0071] (2) Add the above base material, 8.5 parts of methyltributylacetonato silane, 1.5 parts of tetrabutylketoxime silane, 1 part of a customized coupling agent oligomer (R1 is methyl; R2 is phenyltetradecyl; R3 is methyl; X is N-(β-aminoethyl)-γ-aminopropyl); n=8), 3 parts of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 0.05 parts of dibutyltin diacetate into a high-speed planetary mixer, and stir under vacuum at a vacuum degree of -0.091 MPa to obtain the product.

[0072] Example 7

[0073] This embodiment is substantially the same as embodiment 1, except that 2.5 parts of a custom-made coupling agent oligomer (R1 is methyl; R2 is nonyl; R3 is ethyl; X is N-(β-aminoethyl)-γ-aminopropyl); n=3) are used.

[0074] Example 8

[0075] This embodiment is substantially the same as embodiment 1, except that 2.5 parts of a custom-made coupling agent oligomer (R1 is methyl; R2 is phenylpropyl; R3 is ethyl; X is N-(β-aminoethyl)-γ-aminopropyl); n=3) are used.

[0076] Comparative Example 1

[0077] This comparative example is substantially the same as Example 3, except that KH550 is used instead of the coupling agent oligomer.

[0078] Comparative Example 2

[0079] This comparative example is substantially the same as Example 4, except that 3-(diethylenetriamino)propyltrimethoxysilane is used instead of the coupling agent oligomer.

[0080] Sample preparation and performance testing were performed according to GB 16776. The performance test data of the silicone sealants of Examples 1 to 8 and Comparative Examples 1 to 2 are shown in Tables 1, 2 and 3 below.

[0081] Determination of color change after artificial acceleration:

[0082] (1) Prepare samples and measure the degree of discoloration according to GB / T 13477.21. The discoloration levels are divided into 0-3 levels according to "10. Classification of discoloration levels" in the standard, where 0 means no discoloration and 3 means obvious discoloration, which is the highest level.

[0083] (2) High temperature accelerated method: Place the sample prepared and cured according to GB / T 13477.21 in an oven at 200°C for a period of time (7, 28, 56 days), and observe the degree of discoloration in the same way as above.

[0084] Tensile Adhesion after High Temperature Aging:

[0085] High temperature aging treatment method: Place the cured I-shaped parts in an oven at 200°C for a period of time (7, 28, 56 days), and then place them at room temperature for 24 hours. Test their tensile adhesion according to GB 16776.

[0086] Table 1

[0087]

[0088] Table 2

[0089]

[0090] Table 3

[0091]

[0092] It can be seen from the above examples and comparative examples that the discoloration levels of Examples 1-8 are significantly lower than those of Comparative Examples 1-2, indicating that the use of the coupling agent oligomer described in this patent can significantly improve the discoloration of silicone sealant.

[0093] By comparing the effects of Example 3 and Comparative Example 1, it can be seen that under the irradiation conditions specified in GB / T 13477.21, the discoloration degree of Comparative Example 1 using a small molecule aminosilane coupling agent gradually becomes more obvious as the irradiation time increases, while the silicone sealant of Example 3 remains unchanged; at the same time, under high temperature conditions, the silicone sealant of Comparative Example 1 is more likely to change color, while the silicone sealant of Example 3 can still remain unchanged.

[0094] By comparing the effects of Example 4 and Comparative Example 2, it can be seen that under the irradiation conditions specified in GB / T 13477.21, the discoloration degree of Comparative Example 2 using a small molecule triaminosilane coupling agent gradually becomes more obvious as the irradiation time prolongs, and the discoloration occurs faster than that of Comparative Example 1, while the silicone sealant of Example 4 remains unchanged and can still maintain the anti-discoloration ability of Example 3; at the same time, under high temperature conditions, the silicone sealant of Comparative Example 2 undergoes obvious discoloration from the beginning, while the silicone sealant of Example 4 can still remain unchanged and maintain the anti-discoloration ability of Example 3, and its high-temperature tensile bonding strength is more significantly improved than that of Example 3, indicating that the side chain structure of the phenyl alkyl group has a significant effect on improving the anti-discoloration and tensile bonding properties in high-temperature application scenarios.

[0095] By comparing Examples 1-3, although the degree of discoloration is smaller than that of Comparative Example 1, there is still a certain difference, which shows that the length of the long-chain alkane in the side chain also has a certain influence: Examples 2-3 with longer carbon chain structures are better than Example 1.

[0096] By comparing Examples 1, 7, and 8, it is more clearly shown that the preferred long-chain side chains with longer chain alkyl structures perform better in terms of being less prone to discoloration, and the long-chain side chains containing phenyl structures perform better in terms of being less prone to discoloration and have better high-temperature tensile bonding strength.

[0097] By comparing Examples 1-3 and 4-6, it can be seen that the long-chain side chain containing a phenyl structure is more excellent in terms of being less prone to discoloration and having better high-temperature tensile bonding strength.

[0098] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A silicone sealant that is not easy to change color, characterized in that: The components include the following by weight:

2. The non-discoloring silicone sealant according to claim 1, characterized in that: The terminal hydroxyl-terminated polydimethylsiloxane has a viscosity of 3000 to 100000 mPa·s at 25°C.

3. The non-discoloring silicone sealant according to claim 1, characterized in that: The filler is nanometer active calcium carbonate with a particle size of 80±20nm and a cubic crystal shape.

4. The non-discoloring silicone sealant according to claim 1, characterized in that: The dimethyl silicone oil has a viscosity of 100 to 1000 mPa·s at 25°C.

5. The non-discoloring silicone sealant according to claim 1, characterized in that: The crosslinking agent is selected from at least two of phenyltributylacetoximine silane, methyltributylacetoximine silane and tetrabutylketoxime silane.

6. The silicone sealant that is not easy to change color according to claim 1, characterized in that: The coupling agent oligomer has the following general formula: Among them, R1 is methyl, ethyl or propyl; R2 is an alkyl group with 5 to 20 carbon atoms; R3 is methyl or ethyl; X is γ-aminopropyl, N-(β-aminoethyl)-γ-aminopropyl) or 3-(diethylenetriamine)propyl; and n is 3 to 9.

7. The non-discoloring silicone sealant according to claim 6, characterized in that: In the coupling agent oligomer, X is a γ-aminopropyl group, and R2 is an alkyl group having 5 to 20 carbon atoms; Alternatively, in the coupling agent oligomer, X is N-(β-aminoethyl)-γ-aminopropyl), and R2 is an alkyl group having 7 to 20 carbon atoms; Alternatively, in the coupling agent oligomer, X is 3-(diethylenetriamino)propyl, and R2 is an alkyl group having 11 to 20 carbon atoms.

8. The non-discoloring silicone sealant according to claim 1, characterized in that: The epoxy coupling agent is at least one of γ-glycidyloxypropyltrimethoxysilane, epoxycyclohexylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysiloxane.

9. The non-discoloring silicone sealant according to claim 1, characterized in that: The catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate and dibutyltin dioctoate.

10. The method for preparing the silicone sealant that is not prone to discoloration according to any one of claims 1 to 9, characterized in that: The steps include: S1: According to the proportion, the end-hydroxyl-terminated polydimethylsiloxane, filler and dimethyl silicone oil are stirred evenly, and vacuum dehydrated for 2 to 4 hours at a dehydration temperature of 90 to 140° C. and a vacuum degree of -0.09 to 0.1 MPa, and cooled to room temperature to obtain a base material; S2: Add the base material, crosslinking agent, coupling agent oligomer, epoxy coupling agent and catalyst into a high-speed planetary mixer according to the proportion, and stir under vacuum at a vacuum degree of -0.075 to 0.095 MPa to obtain the product.

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