One-component transparent alcohol-type silicone adhesive and method for producing the same

Abstract

The present application relates to the technical field of adhesive, in particular to a single-component transparent alcohol type silicone adhesive and a preparation method thereof.The single-component transparent alcohol type silicone adhesive comprises, by weight fraction, 90-110 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of plasticizer, 10-20 parts of filler, 2-6 parts of end-capping agent, 3-5 parts of crosslinking agent, 1-3 parts of catalyst and 0.1-1 part of adhesion promoter.The single-component transparent alcohol type silicone adhesive prepared by the present application has the characteristics of high transparency, high strength and high elongation, has high displacement capacity, can be widely applied to the bonding requirements of building structures and decoration, has excellent adhesion to metal, aluminum and glass and other materials, weather resistance and aging resistance.In addition, the mechanical properties and adhesion of silicone rubber are less affected by the external environment, ensuring that the transparent alcohol type structural silicone adhesive has good bonding reliability.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and more specifically, to a one-component transparent alcohol-based silicone adhesive and its preparation method. Background Technology

[0002] As people's aesthetic demands for architecture increase, architectural design is paying more attention to the integration of lighting and natural elements, such as the emergence of building structures like glass skylights, point-supported curtain walls, all-glass curtain walls, and transparent skylights. These transparent or semi-transparent building structures, home decorations, and bathroom fixtures require highly transparent sealants for joint sealing to achieve a seamless visual effect.

[0003] Traditional deacid-based silicone sealants produce acetic acid as a byproduct during curing, which has an irritating odor, is corrosive to metals, and cannot bond cement components, limiting their application in the construction industry. Oxime-based sealants release methyl ethyl ketone (MEK) oxime during curing, which is alkaline and corrodes copper and polycarbonate sheets. Furthermore, MEK oxime and organotin compounds pose carcinogenic risks and are environmentally unfriendly, further limiting their application. While alcohol-based silicone sealants undergo de-alcoholization during curing, producing alcohols as byproducts that are less irritating and more environmentally friendly, the following problems still exist:

[0004] (1) Transparency improvement problem: Conventional neutral transparent sealant uses ordinary 107 (hydroxyl-terminated polydimethylsiloxane) in combination with hydrophilic fumed silica. The refractive index difference between ordinary 107 and hydrophilic fumed silica is large, resulting in insufficient transparency of the prepared sealant.

[0005] (2) Viscosity peak problem: There is a viscosity peak in the preparation process of alcohol-based adhesives, which affects the construction performance and product quality.

[0006] (3) Problem of poor mechanical properties of sealant: Transparent alcohol-based sealants generally have poor tensile strength and tear strength, and low elongation, which makes it impossible to use sealants for structural bonding and sealing.

[0007] (4) Corrosion problem: Traditional alcohol-based sealants use organotin or chelated tin as catalysts. Because of their strong acidity, they can cause PC materials to crack, which poses safety risks and leakage risks to the bonding and sealing of home sunrooms. They can also react with the mercury in the mirror, causing spotting problems. Summary of the Invention

[0008] The purpose of this invention is to provide a single-component transparent alcohol-based silicone sealant to solve the technical problems of existing transparent alcohol-based silicone sealants, such as poor transparency, viscosity peaks, poor mechanical properties, and corrosiveness.

[0009] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0010] A single-component transparent alcohol-based silicone sealant, by weight, comprises 90-110 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of plasticizer, 10-20 parts of filler, 2-6 parts of end-capping agent, 3-5 parts of crosslinking agent, 1-3 parts of catalyst, and 0.1-1 parts of adhesion promoter.

[0011] Preferably, the hydroxyl-terminated polydimethylsiloxane is α,β-hydroxyl-terminated polydimethylsiloxane, and its molecular structural formula is as follows: At 25℃, its kinematic viscosity is 5000~20000 mPa•s, and its refractive index is ≥1.4.

[0012] Preferably, the plasticizer is at least one of branched methyl silicone oil and branched dimethyl silicone oil, with a kinematic viscosity of 100–1000 mPa•s at 25°C. Adding the above-mentioned silicone oil as a plasticizer can improve the flexibility of transparent alcohol-based silicone sealants and increase their elongation at break.

[0013] Preferably, the filler is fumed silica, specifically hydrophobic fumed silica post-treated with HMDS (hexamethyldisilazane), with a specific surface area of ​​200–250 nm.

[0014] Preferably, the capping agent is a highly active amine compound, and is at least one of N-[(triethoxysilyl)methyl]ethylenediamine, N-[(triethoxysilyl)methyl]aniline, and bis[3-(triethoxysilyl)propyl]amine.

[0015] Preferably, the crosslinking agent is a mixture of polymethyltrimethoxysilane and methyltrimethoxysilane in a weight ratio of 3:2.

[0016] Preferably, the catalyst is at least one of tetraisopropyl titanate, tetratert-butyl titanate, and trialkoxyphosphate-butyl titanate dimer.

[0017] Preferably, the adhesion promoter is a mixture of γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-isocyanate propyltrimethoxysilane in a weight ratio of 1:1:1.

[0018] Preferably, the adhesion promoter is prepared by: slowly adding γ-aminopropyltrimethoxysilane to γ-isocyanate propyltrimethoxysilane while stirring; then slowly adding γ-glycidyl etheroxypropyltrimethoxysilane while stirring; after stirring and mixing evenly, heating to 105°C for reflux treatment for 2 hours, cooling, and then storing under dry nitrogen gas.

[0019] The transparent alcohol-based silicone sealant of this invention first improves transparency by selecting specific base polymers and plasticizers, and using silazane-treated fumed silica to make the refractive index of the sealant more uniform. Secondly, by using active amino silanes to modify the hydroxyl groups at the 107 end to alkoxy groups, not only is the viscosity peak problem of the sealant solved, but the shelf life is also extended. Furthermore, the alkoxy-terminated 107 can be directly catalyzed by environmentally friendly colorless to slightly yellow titanium complexes without affecting the transparency. Further, through the alkoxy modification technology of ordinary 107 sealant and the silazane-treated fumed silica, the filling amount of fumed silica can be increased from 8% to 20%, thereby improving the mechanical properties of the transparent alcohol-based sealant by more than 50%. In addition, by using environmentally friendly colorless to slightly yellow titanium complexes as catalysis, it is ensured that the sealant cures neutrally and without corrosion, preventing cracking of the sunroom material.

[0020] Another object of the present invention is to provide a method for preparing the aforementioned single-component transparent alcohol-based silicone sealant, which includes the following steps:

[0021] S1: Add hydroxyl-terminated polydimethylsiloxane and end-capping agent in proportion in a dynamic mixing planetary machine, heat to 80-100℃, and stir for 1 hour under vacuum of -0.095MPa; then introduce 20℃ cold water to lower the material temperature to room temperature to obtain end-capped 107 with uniform appearance.

[0022] S2: Add the filler in batches. After it has been completely added, scrape the sides and paddles, and stir the reaction under vacuum of -0.095MPa for 0.5h.

[0023] S3: Add plasticizer and crosslinking agent to the planetary mixing machine and stir for 15 minutes under nitrogen protection;

[0024] S4: Add catalyst and adhesion promoter to the planetary mixing machine, slowly vacuum and stir for 5 minutes. After the vacuum reaches -0.095MPa, continue stirring for 30 minutes to obtain the single-component transparent alcohol-type silicone sealant.

[0025] In summary, the embodiments provided by the above-described technical solutions of the present invention have the following beneficial effects:

[0026] (1) The single-component transparent alcohol-type silicone sealant of the present invention uses high refractive index end-hydroxyl-terminated 107 sealant and nano-level fumed silica treated with silazane to prepare a high-transparency structural silicone sealant.

[0027] (2) The present invention uses tetraisopropyl titanate, tetratert-butyl titanate, and trimoxybutyl phosphate titanate dimer as catalysts, which avoids the problem of PC material cracking caused by the acidity of the catalyst. At the same time, the use of transparent catalysts further improves the transparency of alcohol-based adhesives.

[0028] (3) The present invention uses amine compounds to end 107 glue, which improves the stability of transparent alcohol-type glue and allows it to be stored for up to 9 months.

[0029] (4) The present invention uses fumed silica treated with silazane, which increases the filling amount of reinforcing material from about 8% to about 20%, solving the defects of poor mechanical properties and flexibility of alcohol-based transparent adhesive, so that the tensile strength can reach up to 3MPa and the elongation exceeds 400%, expanding its application in building structure bonding and home decoration aesthetics. Detailed Implementation

[0030] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0031] Example 1

[0032] This embodiment provides a single-component transparent alcohol-based silicone sealant, which, by weight, comprises 100 parts of hydroxyl-terminated polydimethylsiloxane, 15 parts of plasticizer, 15 parts of filler, 4 parts of end-capping agent, 3.5 parts of crosslinking agent, 1.8 parts of catalyst, and 0.8 parts of adhesion promoter.

[0033] The hydroxyl-terminated polydimethylsiloxane has a kinematic viscosity of 5000 mPa•s at 25℃ and a refractive index of 1.4; the plasticizer is branched methyl silicone oil with a kinematic viscosity of 100 mPa•s at 25℃; the filler is hydrophobic fumed silica post-treated with HMDS (hexamethyldisilazane) with a specific surface area of ​​200-250 nm; the end-capping agent is N-[(triethoxysilyl)methyl]ethylenediamine; the crosslinking agent is a mixture of polymethyltrimethoxysilane and methyltrimethoxysilane in a weight ratio of 3:2; the catalyst is tetraisopropyl titanate; and the accelerator is a mixture of γ-aminopropyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and γ-isocyanate propyltrimethoxysilane in a weight ratio of 1:1:1.

[0034] The above-mentioned adhesion promoter is prepared by: slowly adding γ-aminopropyltrimethoxysilane to γ-isocyanate propyltrimethoxysilane while stirring; then slowly adding γ-glycidyl etheroxypropyltrimethoxysilane while stirring; after stirring and mixing evenly, heating to 105℃ for reflux treatment for 2 hours, cooling and then storing under dry nitrogen gas.

[0035] The above-mentioned single-component transparent alcohol-based silicone sealant is prepared by the following method, which includes the following steps:

[0036] S1: Add hydroxyl-terminated polydimethylsiloxane and end-capping agent in proportion in a dynamic mixing planetary machine, heat to 90℃, and stir for 1 hour under vacuum of -0.095MPa; then pass in 20℃ cold water to lower the material temperature to room temperature to obtain end-capped 107 with uniform appearance.

[0037] S2: Add the filler in batches. After it has been completely added, scrape the sides and paddles, and stir the reaction under vacuum of -0.095MPa for 0.5h.

[0038] S3: Add plasticizer and crosslinking agent to the planetary mixing machine and stir for 15 minutes under nitrogen protection;

[0039] S4: Add catalyst and adhesion promoter to the planetary mixing machine, slowly vacuum and stir for 5 minutes. After the vacuum reaches -0.095MPa, continue stirring for 30 minutes to obtain a single-component transparent alcohol-type silicone sealant. Example 2

[0040] The difference in raw material composition between this example and Example 1 is that the plasticizer is branched methyl silicone oil with a kinematic viscosity of 1000 mPa•s at 25°C. The preparation method is the same as in Example 1. Example 3

[0041] The difference in raw material composition between this example and Example 1 is that the kinematic viscosity of the hydroxyl-terminated polydimethylsiloxane at 25°C is 20000 mPa•s. The preparation method is the same as in Example 1. Example 4

[0042] The difference between the raw material composition and that of Example 1 is that the hydroxyl-terminated polydimethylsiloxane has a kinematic viscosity of 20,000 mPa•s at 25°C; and the plasticizer is branched methyl silicone oil with a kinematic viscosity of 1,000 mPa•s at 25°C. The preparation method is the same as that of Example 1.

[0043] Comparative Example 1

[0044] The difference in raw material composition between this example and Example 1 is that the capping agent is omitted. The difference in preparation method between this example and Example 1 is that hydroxyl-terminated polydimethylsiloxane is used as the product of step S1, and then subsequent steps S2 to S4 are performed.

[0045] Comparative Example 2

[0046] The difference in raw material composition between this example and Example 1 is that the filler is fumed silica that has not been treated with HMDS. The preparation method is the same as in Example 1.

[0047] Comparative Example 3

[0048] The difference between the raw material composition and that of Example 1 is that the catalyst is dibutyltin bis(ethyl acetoacetate). The preparation method is the same as that of Example 1.

[0049] Comparative Example 4

[0050] The difference in raw material composition between this example and Example 1 is that the capping agent is methyltrimethoxysilane. The preparation method is the same as in Example 1.

[0051] Comparative Example 5

[0052] Commercially available single-component, single-component, deoxime-type silicone sealant.

[0053] The sealants used in the above embodiments and comparative examples were subjected to the following performance tests, and the results are shown in Tables 1 and 2:

[0054] (1) Surface drying time: in accordance with GB / T 13477.5-2003 (Test methods for building sealing materials - Part 5: Determination of surface drying time).

[0055] (2) Light transmittance: The transmittance shall be determined in accordance with GB / T 2410-2008 (7.2: Spectrophotometer method for determination of light transmittance and haze of transparent plastics).

[0056] (3) Tensile strength: According to GB / T 13477.8-2003 (Test methods for building sealing materials - Part 8: Test of tensile bond strength at 23°C).

[0057] (4) Elongation at break: According to GB / T 13477.8-2003 (Test methods for building sealing materials, part 8: test of elongation at maximum strength at 23℃).

[0058] (5) Adhesion: Tested in accordance with GB / T 13477.8-2003 (Test methods for building sealant - Part 8: Test of the area of ​​bond failure).

[0059] Table 1 Performance data of the embodiments

[0060]

[0061] Table 2 Performance data of the comparative examples

[0062]

[0063] As can be seen from the data of the examples and comparative examples in Tables 1 and 2, the light transmittance of Examples 1-4 all reached 95%, with Example 4 showing superior tensile strength, elongation at break, and high displacement. Compared to Example 1, Comparative Example 1 used hydroxyl polydimethylsiloxane without end-capping agent treatment, resulting in insufficient light transmittance and making it difficult to achieve a seamless visual effect with highly transparent decorative materials in practical applications. Compared to Example 1, Comparative Example 2 used fumed silica without HMDS treatment, resulting in lower tensile strength, elongation at break, and displacement capabilities, making it unsuitable for structural bonding and sealing in practical applications. Compared to Example 1, Comparative Example 3 used an organotin catalyst, which poses a carcinogenic risk, is environmentally unfriendly, and is detrimental to improving colloidal transparency. Compared to Example 1, Comparative Example 4 used a non-highly reactive amine compound, which is detrimental to improving colloidal transparency, tensile strength, and elongation at break. Compared with Example 1, Comparative Example 5 is far inferior to Example 1 in terms of transparency, tensile strength and displacement level performance.

[0064] In summary, the single-component transparent alcohol-based silicone sealant provided by this invention features high transparency, high strength, and high elongation, exhibiting excellent displacement capability. It can be widely applied to the bonding of building structures and the aesthetic bonding requirements of decoration. It also demonstrates excellent adhesion, weather resistance, and aging resistance to materials such as metals, aluminum, and glass. Furthermore, the mechanical and adhesive properties of silicone rubber are less affected by the external environment, ensuring that the transparent alcohol-based structural silicone sealant possesses reliable adhesive performance.

[0065] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A single-component transparent alcohol-based silicone sealant, characterized in that, By weight, it includes 90-110 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of plasticizer, 10-20 parts of filler, 2-6 parts of end-capping agent, 3-5 parts of crosslinking agent, 1-3 parts of catalyst, and 0.1-1 parts of adhesion promoter; The filler is fumed silica, specifically hydrophobic fumed silica post-treated with HMDS, with a specific surface area of ​​200–250 nm. The end-capping agent is at least one of N-[(triethoxysilyl)methyl]ethylenediamine, N-[(triethoxysilyl)methyl]aniline, and bis[3-(triethoxysilyl)propyl]amine; The crosslinking agent is a mixture of polymethyltrimethoxysilane and methyltrimethoxysilane; The catalyst is at least one of tetraisopropyl titanate, tetratert-butyl titanate, and trimoxybutyl phosphate titanate dimer. In this process, hydroxyl-terminated polydimethylsiloxane and a capping agent are heated to 80-100°C and stirred for 1 hour under a vacuum of -0.095 MPa. Then, cold water at 20°C is introduced to lower the material temperature to room temperature, resulting in a uniformly end-capped polydimethylsiloxane.

2. The single-component transparent alcohol-based silicone sealant according to claim 1, characterized in that, The molecular structural formula of the hydroxyl-terminated polydimethylsiloxane is as follows: At 25℃, its kinematic viscosity is 5000~20000 mPa•s, and its refractive index is ≥1.

4.

3. The single-component transparent alcohol-based silicone sealant according to claim 1, characterized in that, The plasticizer is at least one of branched methyl silicone oil and branched dimethyl silicone oil.

4. The single-component transparent alcohol-based silicone sealant according to claim 1, characterized in that, The adhesion promoter is a mixture of γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-isocyanate propyltrimethoxysilane.

5. The single-component transparent alcohol-based silicone sealant according to claim 1, characterized in that, The adhesion promoter is prepared by: slowly adding γ-aminopropyltrimethoxysilane to γ-isocyanate propyltrimethoxysilane while stirring; then slowly adding γ-glycidyl etheroxypropyltrimethoxysilane while stirring; after stirring and mixing evenly, heating to 105°C for reflux treatment for 2 hours, cooling, and then storing under dry nitrogen gas.

6. The method for preparing a single-component transparent alcohol-based silicone sealant according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Add hydroxyl-terminated polydimethylsiloxane and end-capping agent in proportion in a dynamic mixing planetary machine, heat to 80-100℃, and stir for 1 hour under vacuum of -0.095MPa; then introduce 20℃ cold water to lower the material temperature to room temperature to obtain end-capped 107 with uniform appearance. S2: Add the filler in batches. After it has been completely added, scrape the sides and paddles, and stir the reaction under vacuum of -0.095MPa for 0.5h. S3: Add plasticizer and crosslinking agent to the planetary mixing machine and stir for 15 minutes under nitrogen protection; S4: Add catalyst and adhesion promoter to the planetary mixing machine, slowly vacuum and stir for 5 minutes. After the vacuum reaches -0.095MPa, continue stirring for 30 minutes to obtain the single-component transparent alcohol-type silicone sealant.

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