Anti-pollution silicone weather-resistant sealant and preparation method thereof

Abstract

The invention belongs to the technical field of silicone rubber, and particularly relates to an anti-pollution silicone weather-resistant sealant and a preparation method thereof. The preparation method comprises the following steps: carrying out a reaction on hydroxyl-terminated polydimethylsiloxane with the viscosity of 100-1000 mpa.s and a fluoroalkyl dialkoxy silane compound, so as to obtain a D-type fluorosiloxane chain extender; the preparation method comprises the following steps: reacting hydroxyl-terminated polydimethylsiloxane with the viscosity of 20000 to 100000 mpa.s with a fluoroalkyl trialkoxysilane compound to obtain a T-type fluorosiloxane polymer; mixing the T-type fluorosiloxane polymer with the filler, heating and dehydrating, cooling to normal temperature, sequentially adding the D-type fluorosiloxane chain extender, the cross-linking agent, the coupling agent and the catalyst, and uniformly mixing to obtain the anti-pollution silicone weather-resistant sealant.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicone rubber, and particularly relates to an anti-pollution silicone weatherproof sealant and a preparation method thereof. Background Art

[0002] Silicone weatherproof sealants are mainly used for the joint bonding and sealing of building glass curtain walls, stone curtain walls and metal curtain walls. Because ordinary silicone weatherproof sealants contain low-viscosity silicone oil plasticizers, and silicone itself has the characteristic of static electricity, it is easy to adsorb pollutants such as dust and vehicle exhaust in the air, resulting in black pollution around the curtain wall joints and affecting the appearance of the curtain wall.

[0003] The invention patent with the publication number CN 113528080 A discloses a high-displacement anti-pollution silicone sealant and a preparation method thereof, using a difunctional ketoxime-based silane and a trifunctional ketoxime-based silane with a mass ratio of (5-8):(2-5) as crosslinking agents. Without adding plasticizers and avoiding silicone oil seepage pollution, the silicone sealant can have excellent displacement ability and ensure its construction performance. Although the difunctional chain extender in this invention can improve the displacement ability of the glue and does not use methyl silicone oil plasticizer, the silicone glue itself still electrostatically adsorbs dust and vehicle exhaust pollutants in the air, and still causes pollution of the building curtain wall joints.

[0004] The invention patent with the publication number CN 104531049 A discloses an anti-pollution silicone weatherproof sealant and a preparation method thereof. Using a specific silane composite crosslinking agent and its appropriate addition amount can optimize the crosslinked structure after curing of the silicone weatherproof sealant, improve its mechanical property indexes such as elasticity and elongation after curing, and further realize the high-displacement ability of the silicone weatherproof sealant. The appropriate addition amount of fluoroalkyl silane and reasonable combination can effectively reduce the adsorption and accumulation of dust and pollutants on the surface of the glue joint. However, it still uses a deoxime-type crosslinking agent with a high cost, and the reaction uniformity of simply mixing and adding fluoroalkyl silane is poor, resulting in limited anti-pollution ability. Summary of the Invention

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the primary object of the present invention is to provide a preparation method of an anti-pollution silicone weatherproof sealant.

[0006] Another object of the present invention is to provide an anti-pollution silicone weatherproof sealant prepared by the above method.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A preparation method of an anti-pollution silicone weatherproof sealant, comprising the following preparation steps:

[0009] (1) Heat and stir the reaction of hydroxyl-terminated polydimethylsiloxane with a viscosity of 100-1000 mPa·s, fluorohydrocarbyl dialkoxysilane compound and phosphoric acid catalyst under nitrogen protection. After the reaction is completed, add amine for neutralization to obtain D-type fluorosiloxane chain extender;

[0010] (2) Heat and stir the reaction of hydroxyl-terminated polydimethylsiloxane with a viscosity of 20000-100000 mPa·s, fluorohydrocarbyl trialkoxysilane compound and phosphoric acid catalyst under nitrogen protection. After the reaction is completed, add amine for neutralization to obtain T-type fluorosiloxane polymer;

[0011] (3) Mix and heat the T-type fluorosiloxane polymer obtained in step (2) with the filler for dehydration. After cooling to room temperature, add the D-type fluorosiloxane chain extender obtained in step (1), as well as crosslinking agent, coupling agent and catalyst in sequence and mix evenly to obtain anti-pollution silicone weatherproof sealant.

[0012] Preferably, the mass ratio of each raw material in step (1) is: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of fluorohydrocarbyl dialkoxysilane compound, 0.05-0.2 part of phosphoric acid, and 0.02-0.08 part of amine.

[0013] Preferably, the fluorohydrocarbyl dialkoxysilane compound in step (1) is any one of 3,3,3-trifluoropropylmethyldimethoxysilane, 3,3,3-trifluoropropylmethyldiethoxysilane, 1H,1H,2H,2H-perfluorooctylmethyldimethoxysilane, 1H,1H,2H,2H-perfluorooctylmethyldiethoxysilane, dodecafluorheptylpropylmethyldimethoxysilane, 1H,1H,2H,2H-perfluorodecylmethyldimethoxysilane, 1H,1H,2H,2H-perfluorodecylmethyldiethoxysilane.

[0014] Preferably, the amine in steps (1) and (2) is ethylenediamine or propylenediamine.

[0015] Preferably, the temperature of the heat and stir mixing reaction in steps (1) and (2) is 50-70 °C, and the time is 30-120 min.

[0016] Preferably, the mass ratio of each raw material in step (2) is: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of fluorohydrocarbyl trialkoxysilane compound, 0.05-0.2 part of phosphoric acid, and 0.02-0.08 part of amine.

[0017] Preferably, the fluorohydrocarbyl trialkoxysilane compound in step (2) is any one of trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, dodecafluoroheptylpropyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane.

[0018] Preferably, the mass ratio of each raw material in step (3) is as follows: 100 - 120 parts of T-type fluorosilicone polymer, 90 - 120 parts of filler, 10 - 20 parts of D-type fluorosilicone chain extender, 3 - 7 parts of crosslinking agent, 0.5 - 1.5 parts of coupling agent, and 0.01 - 0.1 part of catalyst.

[0019] Preferably, the filler in step (3) is any one of nano calcium carbonate and white carbon black.

[0020] Preferably, the heat dehydration in step (3) means dehydrating for 2 - 3 h under vacuum at a temperature of 100 - 150 °C.

[0021] Preferably, the crosslinking agent in step (3) is vinyltrimethoxysilane or vinyltriethoxysilane; the coupling agent is any one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, γ - aminoethylaminopropyltrimethoxysilane, γ - aminoethylaminopropyltriethoxysilane, 3-(2,3 - epoxypropoxy)propyltrimethoxysilane, 3-(2,3 - epoxypropoxy)propyltriethoxysilane.

[0022] Preferably, the catalyst in step (3) is a chelating tin catalyst.

[0023] An anti - pollution silicone weather - resistant sealant is prepared by the above - mentioned method.

[0024] The principle of the present invention is as follows: By pre - reacting low - viscosity hydroxyl - terminated polydimethylsiloxane with fluorohydrocarbyl dialkoxysilane compound, mainly a D - type (bifunctional reactive polysiloxane) chain extender capped with fluorosilane is generated under a certain material ratio and suitable reaction conditions. The specific reaction formula is exemplified as follows:

[0025]

[0026] By pre - reacting high - viscosity hydroxyl - terminated polydimethylsiloxane with fluorohydrocarbyl trialkoxysilane compound, mainly a T - type (trifunctional reactive polysiloxane) polymer capped with fluorosilane is generated under a certain material ratio and suitable reaction conditions. The specific reaction formula is exemplified as follows:

[0027]

[0028] The present invention pre - reacts difunctional fluorosilane with low - viscosity hydroxyl - terminated polydimethylsiloxane, and pre - reacts trifunctional fluorosilane with high - viscosity hydroxyl - terminated polydimethylsiloxane. On the one hand, it effectively inhibits the self - condensation reaction of fluorosilane during the subsequent curing process; on the other hand, it effectively balances the difference in reactivity of high - and low - viscosity hydroxyl - terminated polydimethylsiloxanes, prevents the over - crosslinking of low - viscosity hydroxyl - terminated polydimethylsiloxane with crosslinking agents and coupling agents, effectively controls the crosslinking density and makes the distribution of fluorohydrocarbon groups in the crosslinked polymer more uniform, thereby improving the displacement ability of silicone sealant and significantly enhancing the anti - pollution effect of silicone sealant.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The silicone weather - resistant sealant of the present invention has better hydrophobic, oleophobic and anti - pollution properties after curing, can fundamentally solve the pollution problem of curtain wall joints generated during the use of silicone sealant, makes the curtain wall appearance cleaner, reduces the number of high - altitude cleaning of the curtain wall, and has good social benefits.

[0031] (2) The silicone weather - resistant sealant of the present invention has good displacement ability and mechanical properties, and has good market prospects.

[0032] (3) The preparation process of the silicone weather - resistant sealant of the present invention is simple, easy to industrialize, and has low cost. Specific embodiments

[0033] The following further describes the present invention in detail with reference to embodiments, but the embodiments of the present invention are not limited thereto.

[0034] Embodiment 1

[0035] A preparation method of an anti - pollution silicone weather - resistant sealant includes the following preparation steps:

[0036] (1) 100 parts of hydroxyl - terminated polydimethylsiloxane with a viscosity of 500 mPa·s, 10 parts of 3,3,3 - trifluoropropylmethyldimethoxysilane and 0.1 part of phosphoric acid catalyst are heated to 60 °C and stirred and mixed in a high - speed disperser for 60 min under nitrogen protection, then 0.05 part of ethylenediamine is added for neutralization, and stirring continues for 60 min to obtain a low - viscosity D - type fluorosiloxane chain extender.

[0037] (2) Under nitrogen protection, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 50000 mPa·s, 10 parts of 3,3,3-trifluoropropyltrimethoxysilane, and 0.1 part of phosphoric acid catalyst were heated to 60 °C in a high-speed disperser and stirred and mixed for 60 min. Then, 0.05 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a high-viscosity T-type fluorosilicone polymer.

[0038] (3) 100 parts of nano-calcium carbonate were added to the T-type fluorosilicone polymer obtained in step (2). The temperature was raised to 120 °C, and dehydration was carried out by high-speed stirring under vacuum for 2 h. After cooling to room temperature, 15 parts of the D-type fluorosilicone chain extender obtained in step (1), 4 parts of vinyltrimethoxysilane, 1 part of aminopropyltrimethoxysilane, and 0.01 part of chelating tin catalyst were added in sequence, and vacuum stirring was carried out for 40 min to mix evenly, obtaining an anti-pollution silicone weather-resistant sealant.

[0039] Example 2

[0040] A preparation method of an anti-pollution silicone weather-resistant sealant, comprising the following preparation steps:

[0041] (1) Under nitrogen protection, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, 10 parts of 1H,1H,2H,2H-perfluorooctylmethyldimethoxysilane, and 0.1 part of phosphoric acid catalyst were heated to 60 °C in a high-speed disperser and stirred and mixed for 60 min. Then, 0.05 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a low-viscosity D-type fluorosilicone chain extender.

[0042] (2) Under nitrogen protection, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 50000 mPa·s, 10 parts of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 0.1 part of phosphoric acid catalyst were heated to 60 °C in a high-speed disperser and stirred and mixed for 60 min. Then, 0.05 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a high-viscosity T-type fluorosilicone polymer.

[0043] (3) 100 parts of nano-calcium carbonate were added to the T-type fluorosilicone polymer obtained in step (2). The temperature was raised to 120 °C, and dehydration was carried out by high-speed stirring under vacuum for 2 h. After cooling to room temperature, 15 parts of the D-type fluorosilicone chain extender obtained in step (1), 4 parts of vinyltrimethoxysilane, 1 part of aminopropyltrimethoxysilane, and 0.01 part of chelating tin catalyst were added in sequence, and vacuum stirring was carried out for 40 min to mix evenly, obtaining an anti-pollution silicone weather-resistant sealant.

[0044] Example 3

[0045] A preparation method of an anti-pollution silicone weather-resistant sealant, comprising the following preparation steps:

[0046] (1) Under the protection of nitrogen, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, 10 parts of dodecafluoroheptylpropylmethyldimethoxysilane, and 0.1 part of phosphoric acid catalyst were heated to 60 °C in a high-speed disperser and stirred and mixed for 60 min, then 0.05 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a low-viscosity D-type fluorosilicone chain extender.

[0047] (2) Under the protection of nitrogen, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 50000 mPa·s, 10 parts of dodecafluoroheptylpropyltrimethoxysilane, and 0.1 part of phosphoric acid catalyst were heated to 60 °C in a high-speed disperser and stirred and mixed for 60 min, then 0.05 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a high-viscosity T-type fluorosilicone polymer.

[0048] (3) 100 parts of nano-calcium carbonate were added to the T-type fluorosilicone polymer obtained in step (2), the temperature was raised to 120 °C, and dehydration was carried out by high-speed stirring under vacuum for 2 h. After cooling to room temperature, 15 parts of the D-type fluorosilicone chain extender obtained in step (1), 4 parts of vinyltrimethoxysilane, 1 part of aminopropyltrimethoxysilane, and 0.01 part of chelating tin catalyst were added in sequence, and vacuum stirring was carried out for 40 min to mix evenly to obtain an anti-pollution silicone weatherproof sealant.

[0049] Example 4

[0050] A preparation method of an anti-pollution silicone weatherproof sealant, comprising the following preparation steps:

[0051] (1) Under the protection of nitrogen, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 100 mPa·s, 15 parts of 1H,1H,2H,2H-perfluorooctylmethyldimethoxysilane, and 0.05 part of phosphoric acid catalyst were heated to 50 °C in a high-speed disperser and stirred and mixed for 30 min, then 0.02 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a low-viscosity D-type fluorosilicone chain extender.

[0052] (2) Under the protection of nitrogen, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 100000 mPa·s, 15 parts of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and 0.2 part of phosphoric acid catalyst were heated to 70 °C in a high-speed disperser and stirred and mixed for 120 min, then 0.08 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a high-viscosity T-type fluorosilicone polymer.

[0053] (3) Add 90 parts of nano calcium carbonate to the T-type fluorosilicone polymer obtained in step (2), heat up to 120 °C and stir at high speed under vacuum conditions for 2 h to dehydrate, then add 10 parts of the D-type fluorosilicone chain extender obtained in step (1), 6 parts of vinyltrimethoxysilane, 1.5 parts of aminopropyltrimethoxysilane and 0.02 part of chelating tin catalyst in sequence after cooling to room temperature, and stir under vacuum for 40 min to mix evenly to obtain the anti-pollution silicone weatherproof sealant.

[0054] Example 5

[0055] A preparation method of an anti-pollution silicone weatherproof sealant, comprising the following preparation steps:

[0056] (1) Under the protection of nitrogen, heat 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 1000 mPa·s, 20 parts of 1H,1H,2H,2H-perfluorodecylmethyldimethoxysilane and 0.2 part of phosphoric acid catalyst to 70 °C in a high-speed disperser, stir and mix for 120 min, then add 0.08 part of ethylenediamine for neutralization, and continue to stir for 60 min to obtain a low-viscosity D-type fluorosilicone chain extender.

[0057] (2) Under the protection of nitrogen, heat 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 20000 mPa·s, 20 parts of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane and 0.05 part of phosphoric acid catalyst to 50 °C in a high-speed disperser, stir and mix for 60 min, then add 0.02 part of ethylenediamine for neutralization, and continue to stir for 60 min to obtain a high-viscosity T-type fluorosilicone polymer.

[0058] (3) Add 120 parts of nano calcium carbonate to the T-type fluorosilicone polymer obtained in step (2), heat up to 120 °C and stir at high speed under vacuum conditions for 2 h to dehydrate, then add 20 parts of the D-type fluorosilicone chain extender obtained in step (1), 3 parts of vinyltrimethoxysilane, 0.5 part of aminopropyltrimethoxysilane and 0.02 part of chelating tin catalyst in sequence after cooling to room temperature, and stir under vacuum for 40 min to mix evenly to obtain the anti-pollution silicone weatherproof sealant.

[0059] Example 6

[0060] A preparation method of an anti-pollution silicone weatherproof sealant, comprising the following preparation steps:

[0061] (1) Under the protection of nitrogen, heat 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, 15 parts of 3,3,3-trifluoropropylmethyldimethoxysilane and 0.1 part of phosphoric acid catalyst to 60 °C in a high-speed disperser, stir and mix for 60 min, then add 0.05 part of ethylenediamine for neutralization, and continue to stir for 60 min to obtain a low-viscosity D-type fluorosilicone chain extender.

[0062] (2) Under the protection of nitrogen, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 50,000 mPa·s, 15 parts of 3,3,3-trifluoropropyltrimethoxysilane, and 0.1 part of phosphoric acid catalyst were heated to 60 °C in a high-speed disperser and stirred and mixed for 60 min. Then, 0.05 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a high-viscosity T-shaped fluorosilicone polymer.

[0063] (3) 100 parts of fumed silica was added to the T-shaped fluorosilicone polymer obtained in step (2), and the temperature was raised to 120 °C and dehydrated by high-speed stirring under vacuum for 2 h. After cooling to room temperature, 15 parts of the D-shaped fluorosilicone chain extender obtained in step (1), 7 parts of vinyltrimethoxysilane, 1 part of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and 0.01 part of chelating tin catalyst were added in sequence and stirred under vacuum for 40 min to mix evenly, obtaining an anti-pollution silicone weatherproof sealant.

[0064] Comparative Example 1

[0065] This comparative example is a conventional ketoxime-type crosslinked silicone weatherproof sealant, and the preparation steps are as follows:

[0066] 100 parts of nano calcium carbonate was added to 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 50,000 mPa·s. The temperature was raised to 120 °C and dehydrated by high-speed stirring under vacuum for 2 h. After cooling to room temperature, 2 parts of dimethyldibutylketoxime-based silane, 4 parts of methyltributylketoxime-based silane, 4 parts of vinyltributylketoxime-based silane, 1 part of aminopropyltrimethoxysilane, and 0.01 part of dibutyltin dilaurate catalyst were added in sequence and stirred under vacuum for 40 min to mix evenly, obtaining an anti-pollution silicone weatherproof sealant.

[0067] Comparative Example 2

[0068] A preparation method of an anti-pollution silicone weatherproof sealant, compared with Example 1, without adding a low-viscosity D-shaped fluorosilicone chain extender, includes the following preparation steps:

[0069] (1) Under the protection of nitrogen, 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 50,000 mPa·s, 10 parts of 3,3,3-trifluoropropyltrimethoxysilane, and 0.1 part of phosphoric acid catalyst were heated to 60 °C in a high-speed disperser and stirred and mixed for 60 min. Then, 0.05 part of ethylenediamine was added for neutralization, and stirring was continued for 60 min to obtain a high-viscosity T-shaped fluorosilicone polymer.

[0070] (2) 100 parts of nano calcium carbonate was added to the T-shaped fluorosilicone polymer obtained in step (1), and the temperature was raised to 120 °C and stirred at high speed under vacuum conditions for 2 h to dehydrate. After cooling to room temperature, 4 parts of vinyltrimethoxysilane, 1 part of aminopropyltrimethoxysilane and 0.01 part of chelating tin catalyst were added in sequence and stirred under vacuum for 40 min to mix evenly, obtaining an anti-pollution silicone weatherproof sealant.

[0071] Comparative Example 3

[0072] A preparation method of an anti-pollution silicone weatherproof sealant. Compared with Example 1, 3,3,3-trifluoropropylmethyldimethoxysilane and 3,3,3-trifluoropropyltrimethoxysilane were not pre-reacted with hydroxyl-terminated polydimethylsiloxane, and the preparation steps were as follows:

[0073] 100 parts of nano calcium carbonate was added to 100 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 50000 mPa·s, and the temperature was raised to 120 °C and stirred at high speed under vacuum conditions for 2 h to dehydrate. After cooling to room temperature, 13.5 parts of hydroxyl-terminated polydimethylsiloxane with a viscosity of 500 mPa·s, 1.5 parts of 3,3,3-trifluoropropylmethyldimethoxysilane, 10 parts of 3,3,3-trifluoropropyltrimethoxysilane, 4 parts of vinyltrimethoxysilane, 1 part of aminopropyltrimethoxysilane and 0.01 part of chelating tin catalyst were added in sequence and stirred under vacuum for 40 min to mix evenly, obtaining an anti-pollution silicone weatherproof sealant.

[0074] The anti-pollution performance test and mechanical property test were carried out on the silicone weatherproof sealants of the above examples and comparative examples. Tensile test specimens were made according to GB / T 528. The curing time of the film was 7 days.

[0075] Test method for contact angle: The prepared film was placed on a contact angle measuring instrument, and a drop of engine oil was dropped on the film with a dropper. Photos were taken first and then the contact angle was measured with a protractor.

[0076] Test method for oil resistance: The prepared film was weighed and the weight M1 of each film was recorded, then it was put into 5W-40 engine oil and completely submerged for 48 hours, taken out, and the new weight M2 was measured, and the mass change rate of the glue was calculated.

[0077] Test method for silicone surface contamination: 2 grams of oil contaminants were dropped on the prepared film, and after standing for 2 hours, the oil was wiped off with a clean white cloth, and the obvious degree of the oil mark on the surface of the glue was observed.

[0078] The test results are shown in Table 1 and Table 2 below.

[0079] Table 1. Performance test results of the silicone weatherproof sealants of Examples 1-6

[0080] Test Items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Contact Angle / θ 123 127 119 123 131 122 Mass Change Rate after Oil Immersion / % 5.3 7.1 6.5 5.0 7.2 5.2 Pollution Imprint with Applied Oil Not Obvious Not Obvious Not Obvious Not Obvious Not Obvious Not Obvious Pollution Imprint with Applied Soy Sauce Not Obvious Not Obvious Not Obvious Not Obvious Not Obvious Not Obvious Tensile Strength / Mpa 1.6 1.7 1.5 2.0 1.5 1.8 Elongation at Break / % 467 472 483 450 495 462 Shore Hardness / A 32 35 31 35 34 32

[0081] Table 2. Performance test results of silicone weather sealants of Comparative Examples 1-3

[0082] Test Items Comparative Example 1 Comparative Example 2 Comparative Example 3 Contact Angle / θ 87 109 112 Mass Change Rate after Oil Immersion / % 12.2 9.1 9.7 Pollution Imprint with Applied Oil Relatively Obvious Relatively Obvious Relatively Obvious Pollution Imprint with Applied Soy Sauce Not Obvious Not Obvious Not Obvious Tensile Strength / Mpa 2.1 1.8 1.9 Elongation at Break / % 331 376 352 Shore Hardness / A 42 39 40

[0083] From the above test results, it can be seen that the contact angles of Examples 1-6 increased significantly, the oil smear pollution marks were not obvious, and they had good oil-repellent and anti-pollution properties; the elongation rate increased significantly, the hardness decreased significantly, and they had good displacement ability.

[0084] In Comparative Example 1, no fluorosilane component was added, and a compound cross-linking system of diketoxime-based silane and triketoxime-based silane was used. Its contact angle was small, the water and oil resistance was poor, the strength was high, the elongation at break decreased, the hardness was high, and the displacement ability was poor.

[0085] In Comparative Example 2, no low-viscosity D-type fluorosiloxane chain extender was added, and its oil-repellent and anti-pollution properties and displacement ability were significantly lower than those of the examples.

[0086] In Comparative Example 3, the fluorosilane was not pre-reacted with hydroxyl-terminated polydimethylsiloxane, and its oil-repellent and anti-pollution properties and displacement ability were significantly lower than those of the examples.

[0087] The above examples are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above examples. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing an anti-pollution weather-resistant silicone sealant, characterized in that: The method comprises the following preparation steps: (1) heating and stirring a terminal hydroxyl polydimethylsiloxane having a viscosity of 100 to 1000 mPa.s, a fluoroalkyldialkoxysilane compound and a phosphoric acid catalyst under nitrogen protection to react, and adding an amine for neutralization after the reaction is completed to obtain a D-type fluorosilicone chain extender; (2) heating and stirring a terminal hydroxyl polydimethylsiloxane having a viscosity of 20,000 to 100,000 mPa.s, a fluoroalkyltrialkoxysilane compound and a phosphoric acid catalyst under nitrogen protection to react, and adding an amine to neutralize the reaction to obtain a T-type fluorosilicone polymer; (3) The T-type fluorosilicone polymer obtained in step (2) is mixed with a filler and heated for dehydration. After cooling to room temperature, the D-type fluorosilicone chain extender obtained in step (1) as well as a cross-linking agent, a coupling agent and a catalyst are sequentially added and mixed evenly to obtain an anti-pollution weather-resistant silicone sealant.

2. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The mass proportion of the raw materials in step (1) is: 100 parts of terminal hydroxyl polydimethylsiloxane, 10-20 parts of fluoroalkyldialkoxysilane compound, 0.05-0.2 parts of phosphoric acid, and 0.02-0.08 parts of amine.

3. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The fluoroalkyldialkoxysilane compound in step (1) is any one of trifluoropropylmethyldimethoxysilane, trifluoropropylmethyldiethoxysilane, 1H,1H,2H,2H-perfluorooctylmethyldimethoxysilane, 1H,1H,2H,2H-perfluorooctylmethyldiethoxysilane, dodecafluoroheptylpropylmethyldimethoxysilane, 1H,1H,2H,2H-perfluorodecylmethyldimethoxysilane, and 1H,1H,2H,2H-perfluorodecylmethyldiethoxysilane.

4. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The amine in steps (1) and (2) is ethylenediamine or propylenediamine; the temperature of the heating, stirring and mixing reaction in steps (1) and (2) is 50 to 70° C. and the time is 30 to 120 minutes.

5. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The mass proportion of the raw materials in step (2) is: 100 parts of terminal hydroxyl polydimethylsiloxane, 10-20 parts of fluorocarbon trialkoxy silane compound, 0.05-0.2 parts of phosphoric acid, and 0.02-0.08 parts of amine.

6. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The fluoroalkyltrialkoxysilane compound in step (2) is any one of trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, dodecafluoroheptylpropyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, and 1H,1H,2H,2H-perfluorodecyltriethoxysilane.

7. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The weight ratio of the raw materials in step (3) is: 100-120 parts of T-type fluorosilicone polymer, 90-120 parts of filler, 10-20 parts of D-type fluorosilicone chain extender, 3-7 parts of cross-linking agent, 0.5-1.5 parts of coupling agent, and 0.01-0.1 parts of catalyst.

8. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The filler in step (3) is any one of nano calcium carbonate and white carbon black; the heating dehydration refers to dehydration under vacuum at a temperature of 100 to 150° C. for 2 to 3 hours.

9. The method for preparing an anti-pollution weather-resistant silicone sealant according to claim 1, characterized in that: The cross-linking agent in step (3) is vinyl trimethoxysilane or vinyl triethoxysilane; the coupling agent is any one of aminopropyl trimethoxysilane, aminopropyl triethoxysilane, γ-aminoethylaminopropyl trimethoxysilane, γ-aminoethylaminopropyl triethoxysilane, 3-(2,3-epoxypropoxy)propyl trimethoxysilane, and 3-(2,3-epoxypropoxy)propyl triethoxysilane; and the catalyst is a chelated tin catalyst.

10. An anti-pollution weather-resistant silicone sealant, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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