A solvent-free, sprayable condensation type silicone sealant and preparation method thereof

Abstract

The present invention relates to a solvent-free, sprayable condensation silicone sealant and a preparation method thereof. The present invention uses a silane crosslinking agent with an α-functional group and an organic tin catalyst to enable the silicone sealant to achieve rapid surface drying and film formation under the condition of low viscosity (high hydroxyl content), and uses a non-volatile diluent to enable the prepared silicone sealant to meet the spraying process and rapidly dry and solidify at room temperature to form a dense polymer material film, effectively preventing corrosion of buildings and equipment, and the present invention does not contain volatile organic solvents and is non-toxic and harmless to human body and environment, achieving the effect of being sprayable.

Description

Technical Field

[0001] The invention belongs to the technical field of sealants, and in particular relates to a solvent-free, sprayable condensation-type silicone sealant and a preparation method thereof. Background Art

[0002] Most of the silicone sealants that can be sprayed on the market currently need to add a large amount of solvent to dilute them according to a certain proportion before construction. The solvents used often have pungent odors, are flammable and explosive, and are not conducive to storage, posing safety hazards. In addition, after construction, silicone sealants with added solvents need to be heated to make them cure quickly. During the heating process, if the temperature and time are not well controlled, the solvent will produce bubbles during the volatilization process and remain in the colloid, affecting the relevant properties of the silicone sealant after curing. Existing sprayable silicone sealant products generally have slow surface drying even without the addition of solvents. The surface drying time is mostly between 60-120 minutes, which affects the construction progress. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a condensation-type silicone sealant which does not require the addition of solvents during use, can be directly sprayed and has a fast surface drying speed.

[0004] Another object of the present invention is to provide a method for preparing the condensation type silicone sealant.

[0005] The technical solution adopted to achieve the above invention object is:

[0006] A solvent-free, sprayable condensation silicone sealant, characterized in that its raw material composition by weight is:

[0007]

[0008] The crosslinking agent is compounded by a crosslinking agent A and a crosslinking agent B, wherein the crosslinking agent A is an alkoxysilane or a siloxane, and the crosslinking agent B is an α-functional group silane.

[0009] The viscosity of the α,ω-dihydroxy polydimethylsiloxane is between 400cp and 10000cp.

[0010] The non-volatile diluent is one or more of a dimethylcyclosiloxane mixture, polydimethylsiloxane, and polymethylphenylsiloxane, and has a viscosity between 50cp and 1000cp.

[0011] The crosslinking agent A is one or more of methyltrimethoxysilane, vinyltrimethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, polymethyltriethoxysilane, vinyltriethoxysilane and phenyltriethoxysilane.

[0012] The crosslinking agent B is one or more of dichloromethyltriethoxysilane, anilinemethyltriethoxysilane, diethylaminomethyltriethoxysilane, dichloromethyltrimethoxysilane, anilinemethyltrimethoxysilane and diethylaminomethyltrimethoxysilane.

[0013] The coupling agent is 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, N-2-aminoethyl-3-aminopropyltriethoxysilane, 3-diethylenetriaminopropylmethyldimethoxysilane, 3-diethylenetriaminopropyltrimethoxysilane, N-(2-dimethylaminoethyl)-3-aminopropylmethyldimethoxysilane, N-phenyl-3-amino One or more of propyltrimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, bis(3-triethoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)amine, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0014] The organic tin catalyst is one or more of dibutyltin diacetate, dimethyltin hydroxylate, dimethyltin dioctanoate, dibutyltin diisooctylmaleate, dibutyltin dilaurate and dioctyltin dilaurate.

[0015] The method for preparing the solvent-free, sprayable condensation silicone sealant is characterized in that the process steps are as follows:

[0016] 1) Add α, ω-dihydroxy polydimethylsiloxane and non-volatile diluent into the planetary machine barrel and stir for 15 to 30 minutes under a vacuum degree of -0.090Mpa;

[0017] 2) Stop stirring and return to normal pressure, add crosslinking agent A, and stir for 10 to 20 minutes under a vacuum degree of -0.090 MPa;

[0018] 3) Stop stirring and fill with nitrogen to restore to normal pressure. Under nitrogen protection, add crosslinking agent B, coupling agent and catalyst in sequence and stir for 5 to 15 minutes;

[0019] 4) Turn off the nitrogen and turn on the vacuum, stir for 20 to 40 minutes at a vacuum degree of -0.090 MPa, discharge the material and seal it for storage, and a solvent-free, sprayable condensation silicone sealant can be obtained.

[0020] The functional group and silicon atom in the α-functional group silane crosslinking agent are very close to each other, separated by only one carbon atom, and the electronic effect on the functional group is more easily conducted to the silicon atom, making the alkoxy group in the silicon atom more active. Compared with the silane crosslinking agent without functional group substitution, it is easier to crosslink with α, ω-dihydroxy polydimethylsiloxane. Based on the above, the present invention uses the α-functional group silane crosslinking agent and the organic tin catalyst to make the silicone sealant achieve rapid surface drying and film formation under the condition of low viscosity (high hydroxyl content), and by using a non-volatile diluent, the prepared silicone sealant can quickly dry and solidify at room temperature while meeting the spraying process, forming a dense polymer material film, effectively preventing corrosion of buildings and equipment, and the present invention does not contain volatile organic solvents, and is non-toxic and harmless to the human body and the environment. Achieve the effect of spraying. DETAILED DESCRIPTION

[0021] Example 1

[0022] A solvent-free, sprayable condensation silicone sealant, the raw material composition of which is (by weight):

[0023]

[0024] Preparation method: Add 100 parts of α, ω-dihydroxy polydimethylsiloxane and 50 parts of dimethylcyclosiloxane mixture to the planetary machine barrel, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 9.6 parts of methyltrimethoxysilane and 3.3 parts of vinyltrimethoxysilane, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 4 parts of dichloromethyltriethoxysilane, 0.84 parts of 3-aminopropylmethyldimethoxysilane, 0.42 parts of 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane and 0.1 parts of dibutyltin diacetate in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0025] Example 2

[0026] A solvent-free, sprayable condensation silicone sealant, the raw material composition of which is (by weight):

[0027]

[0028]

[0029] Preparation method: Add 100 parts of α, ω-dihydroxy polydimethylsiloxane and 80 parts of polydimethylsiloxane to the planetary machine barrel, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 7 parts of methyl orthosilicate, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 5 parts of aniline methyl triethoxysilane, 0.84 parts of bis(3-trimethoxysilylpropyl)amine, 0.42 parts of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 0.09 parts of dibutyltin dilaurate in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0030] Example 3

[0031] A solvent-free, sprayable condensation silicone sealant, the raw material composition of which is (by weight):

[0032]

[0033] Preparation method: Add 100 parts of α, ω-dihydroxy polydimethylsiloxane and 100 parts of polydimethylsiloxane to the planetary machine barrel, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 8 parts of polymethyltriethoxysilane and 2 parts of propyltrimethoxysilane, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 6 parts of diethylaminomethyltriethoxysilane, 0.76 parts of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, 0.35 parts of 3-glycidyloxypropyltriethoxysilane and 0.069 parts of hydroxydimethyltin in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0034] Example 4

[0035] A solvent-free, sprayable condensation silicone sealant, the raw material composition of which is (by weight):

[0036]

[0037] Preparation method: Add 30 parts of 1000cp viscosity and 70 parts of 400cp viscosity α, ω-dihydroxy polydimethylsiloxane into the planetary machine barrel, and add 50 parts of dimethylcyclosiloxane mixture, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 7 parts of ethyl orthosilicate and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 7 parts of dichloromethyl trimethoxysilane, 0.82 parts of N-(n-butyl)-3-aminopropyl trimethoxysilane, 0.4 parts of 3-(2,3-epoxypropoxy)propyl trimethoxysilane and 0.082 parts of dimethyltin dichloroacetate in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0038] Example 5

[0039] A solvent-free, sprayable condensation silicone sealant, the raw material composition of which is (by weight):

[0040]

[0041] Preparation method: Add 50 parts of α, ω-dihydroxy polydimethylsiloxane with a viscosity of 1200cp and 50 parts of 500cp in the planetary machine barrel, and add 80 parts of polymethylphenylsiloxane, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 7.6 parts of phenyltrimethoxysilane and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 6.5 parts of aniline methyl trimethoxysilane, 0.9 parts of 3-diethylenetriamine propyl methyl dimethoxysilane, and 0.076 parts of diisooctyl maleate dibutyltin and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0042] Example 6

[0043] A solvent-free, sprayable condensation silicone sealant, the raw material composition of which is (by weight):

[0044]

[0045] Preparation method: Add 100 parts of α, ω-dihydroxy polydimethylsiloxane and 100 parts of polymethylphenylsiloxane to the planetary machine barrel, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 6 parts of vinyl triethoxysilane, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 4.3 parts of diethylaminomethyl trimethoxysilane, 1.1 parts of N-phenyl-3-aminopropyl trimethoxysilane and 0.08 parts of dioctyltin dilaurate in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0046] Comparative Example 1

[0047] A silicone sealant, the raw materials of which are composed of (by weight):

[0048]

[0049]

[0050] Preparation method: Add 100 parts of α, ω-dihydroxy polydimethylsiloxane and 100 parts of polydimethylsiloxane to the planetary machine barrel, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 12 parts of methyl tributylidene oxime silane and 3 parts of vinyl tributylidene oxime silane, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 0.8 parts of γ-aminopropyl triethoxysilane, 0.4 parts of 3-(2,3-epoxypropoxy)propyl trimethoxysilane and 0.1 parts of dibutyltin dilaurate in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0051] Comparative Example 2

[0052] A silicone sealant, the raw materials of which are composed of (by weight):

[0053]

[0054] Preparation method: Add 100 parts of α, ω-dihydroxy polydimethylsiloxane and 100 parts of polydimethylsiloxane to the planetary machine barrel, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and return to normal pressure, add 7.8 parts of methyltrimethoxysilane, and stir for 15 minutes at a vacuum degree of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 0.75 parts of γ-aminopropyltrimethoxysilane and 5 parts of di(ethyl acetoacetate) diisopropoxytitanium in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, and stir for 35 minutes at a vacuum degree of -0.090Mpa. Finally, discharge the material and seal it for storage.

[0055] Comparative Example 3

[0056] A silicone sealant, the raw materials of which are composed of (by weight):

[0057]

[0058]

[0059] Preparation method: Add 100 parts of α, ω-dihydroxy polydimethylsiloxane to the planetary machine barrel and stir for 5 minutes at a vacuum of -0.090Mpa. Then stop stirring and return to normal pressure, add 8.5 parts of methyltrimethoxysilane, and stir for 15 minutes at a vacuum of -0.090Mpa. Then stop stirring and fill with nitrogen to return to normal pressure. Under nitrogen protection, add 5 parts of dichloromethyltriethoxysilane, 0.89 parts of N-aminoethyl-γ-aminopropyltrimethoxysilane and 0.1 parts of dibutyltin diacetate in sequence and stir for 10 minutes. Turn off the nitrogen and open the vacuum, stir for 25 minutes at a vacuum of -0.090Mpa, stop stirring and fill with nitrogen to return to normal pressure, add petroleum ether (solvent) under nitrogen protection, then turn off the nitrogen and open the vacuum, stir for 10 minutes at a vacuum of -0.090Mpa, finally discharge the material and seal it for storage.

[0060] The silicone sealants prepared in the above-mentioned embodiments and comparative examples were tested for performance according to the following standards: the surface drying time was tested according to method B in GB / T 13477.5-2002, the viscosity was tested according to GB / T 2794, the Shore A hardness was tested according to GB / T 531-2008, and the adhesion was tested according to method 2 in Appendix D1.2 of GB 16776-2005. The test results are shown in Tables 1 and 2.

[0061] Table 1 Comprehensive performance test results of various embodiments and comparative examples

[0062] Serial number Viscosity, CP Surface drying time, min Hardness / Shore A Can it be sprayed? Example 1 265 4 33 Sprayable Example 2 378 3.5 31 Sprayable Example 3 235 3.5 30 Sprayable Example 4 560 3 27 Sprayable Example 5 620 2.5 25 Sprayable Example 6 700 2 22 Sprayable Comparative Example 1 287 120 30 Sprayable Comparative Example 2 689 90 23 Sprayable Comparative Example 3 225 360 34 Sprayable

[0063] Table 2 Comparative test of adhesion between Examples 1-6 and Comparative Examples 1-3

[0064]

[0065]

[0066] Note: √ indicates 100% cohesive failure; ○ indicates 50% cohesive failure; × indicates 100% interfacial failure

[0067] It can be seen from the data in Table 1 that the solvent-free sprayable condensation silicone sealant prepared in Examples 1-6 can achieve surface drying within 5 minutes, which is significantly better than the deketoxime system and titanate system silicone sealants prepared in Comparative Examples 1-2. At the same time, for Comparative Example 3, even if an α-functional silane crosslinker plus an organotin catalyst system is used, a large amount of volatile organic solvents are added as diluents, so that the surface drying at room temperature becomes very slow. The results show that the α-functional silane crosslinker used in the present invention plus an organotin catalyst system and a non-volatile diluent can achieve a quick surface drying film formation while achieving a spraying effect. It can be seen from the data in Table 2 that the solvent-free sprayable condensation silicone sealant prepared in Example 2 can meet the bonding requirements of more substrates, and compared with other examples, it has the best comprehensive performance.

[0068] The embodiments disclosed above are for illustrative purposes only and cannot be understood as limiting the present invention. It is obvious to professionals in this field to make various modifications and substitutions within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A solvent-free, sprayable condensation silicone sealant, characterized in that: The raw material composition by weight is:

2. A method for preparing the solvent-free, sprayable condensation silicone sealant as claimed in claim 1, characterized in that: The process steps are: 1) Add α, ω-dihydroxy polydimethylsiloxane and polydimethylsiloxane into the planetary machine barrel and stir for 15 to 30 minutes under a vacuum degree of -0.090Mpa; 2) Stop stirring and return to normal pressure, add methyl orthosilicate, and stir for 10 to 20 minutes at a vacuum degree of -0.090 MPa; 3) Stop stirring and fill with nitrogen to restore to normal pressure. Under nitrogen protection, add aniline methyl triethoxysilane, bis (3-trimethoxysilyl propyl) amine, 2- (3, 4-epoxycyclohexyl) ethyl trimethoxysilane and dibutyltin dilaurate in sequence and stir for 5 to 15 minutes; 4) Turn off the nitrogen and open the vacuum, stir at a vacuum degree of -0.090 MPa for 20 to 40 minutes, discharge the material and seal it for storage.

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