High durability sealant for sealing steel structural plate joints

Abstract

This invention relates to the technical field of sealants, specifically to a high-durability sealant for sealing joints in steel structure panels. It comprises 30-50 parts modified polysiloxane, 1-6 parts silane oligomer, 30-60 parts inorganic filler, 0.1-1 parts thixotropic agent, 0.01-0.2 parts catalyst, 30-60 parts crosslinking agent, 0.3-2 parts silane coupling agent, 0.1-0.5 parts light stabilizer, and 0.1-1 parts antioxidant. Compared with existing technologies, the N and O atoms in the sealant structure of this invention pair with the empty d orbitals of iron atoms on the steel plate surface, forming a coordination effect that inhibits corrosion. This results in a film formation on the metal surface, improving the corrosion resistance of the steel structure panel joint surface and enhancing overall durability, thus offering significant economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of sealing materials technology, specifically relating to a high-durability sealant for sealing seams in steel structure panels. Background Technology

[0002] Long- and medium-span bridges are vital transportation arteries, and their safe operation directly impacts national economic development and social security. Among the various structural forms of railway bridges, steel bridges, compared to concrete bridges, offer advantages such as high strength, simple processing, convenient installation, short construction period, and good bridge toughness and seismic resistance, making them widely used in long- and medium-span bridges. Sealant, as a commonly used joint sealing material, possesses excellent adhesion and durability and can be used to seal steel plate joints in steel structure bridges. Due to the poor corrosion resistance of ordinary steel, and the influence of various factors such as temperature, humidity, ultraviolet radiation, and atmospheric conditions, steel plate surfaces are prone to varying degrees of rust and corrosion. Therefore, efficient and durable sealing of steel plate gaps is crucial for the overall safety and durability of steel structure bridges.

[0003] Based on chemical composition, existing sealants on the market can be divided into silicone sealants, polyurethane sealants, and acrylic sealants. Silicone sealants, in particular, are mainly composed of silicone polymers and a series of additives. Patent CN117801782A discloses a silicone sealant and its preparation method. By using a modified resin with a large amount of benzoxazine and benzene ring structures on its molecular chain, the aging resistance of the silicone sealant is increased. By introducing modified fillers containing cage-like silsesquioxanes and metal-organic frameworks with interwoven structures, the brittleness of the sealant is reduced, and its mechanical properties are improved. Patent CN114621724A discloses a two-component silicone sealant that uses modified oxime-based polydimethylsiloxane in synergy with other formulation components. Compared with existing polyalkoxy-terminated polydimethylsiloxanes, it has higher reactivity and a faster deep curing rate, thus improving the curing speed of the sealant. Patent CN116445127A discloses an underwater-curable silicone sealant, its preparation method, and its applications. It achieves room-temperature crosslinking and curing through a Michael addition and Schiff base reaction between dopamine and the terminal amino groups of diaminopropyl-terminated polydimethylsiloxane. Furthermore, this reaction can occur underwater (or in a humid environment), enabling underwater crosslinking and curing. Simultaneously, because dopamine contains a catechol structure, it can achieve high adhesion to various material surfaces.

[0004] As can be seen from the above description, existing silicone sealants have certain practical value. By introducing different types of organic groups according to different formulations and applications, silicone sealants can acquire certain special properties. However, given the more complex and severe environmental conditions in current railway bridge engineering, a mature sealant product for steel structure joints has not yet been developed. Therefore, providing a steel structure joint sealant that not only exhibits good adhesion to steel plate surfaces but also extends the corrosion resistance of steel plates in humid environments has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a sealing material for steel structure plate joints, as well as a method for preparing the sealing material and its application.

[0006] The present invention discloses a high-durability sealant for sealing joints in steel structure panels, characterized in that the sealant comprises the following components in parts by weight: 30-50 parts modified polysiloxane, 1-6 parts silane oligomer, 30-60 parts inorganic filler, 0.1-1 parts thixotropic agent, 0.01-0.2 parts catalyst, 30-60 parts crosslinking agent, 0.3-2 parts silane coupling agent, 0.1-0.5 parts light stabilizer, and 0.1-1 parts antioxidant.

[0007] The modified polysiloxane has the following general formula:

[0008] In the formula, R is any one of methyl, ethyl, n-propyl, or isopropyl.

[0009] 10≤m≤100, 20≤n≤100, where m and n are both positive numbers.

[0010] The method for preparing the modified polysiloxane includes the following steps:

[0011] Aminopropyl polysiloxane and furfural of appropriate mass were dissolved in tetrahydrofuran (THF), with the molar ratio of amino to aldehyde groups controlled at 1:1. Anhydrous sodium sulfate (Na2SO4) was added, and the mixture was stirred at room temperature for 24 h. Na2SO4 was removed by centrifugation, solvent was removed by rotary evaporation, and the mixture was vacuum dried in an oven for 12 h to obtain modified polysiloxane.

[0012] The number average molecular weight of the modified polysiloxane is 6000~20000.

[0013] The inorganic filler includes at least one of calcium carbonate and silica powder. Further, the calcium carbonate is preferably at least one of heavy calcium carbonate and nano-calcium carbonate.

[0014] The catalyst is composed of one or more of dioctyltin diacetate, dioctyltin dilaurate, dioctyltin dioctanoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctanoate, isopropyl titanate, isobutyl titanate, and n-butyl titanate; the crosslinking agent is composed of one or more of methyltriacetoxysilane, ethyltriacetoxysilane, vinyltriacetoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, or vinyltriethoxysilane.

[0015] The light stabilizer is composed of one or more compounds such as benzotriazole UV absorbers and hindered amine UV stabilizers.

[0016] The silane coupling agent is composed of one or more of 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, or N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane.

[0017] The sealant has good adhesion to slightly corroded steel plates, and the adhesion strength on the steel surface can reach 3MPa and above.

[0018] The positive effects of the steel structure joint sealant of the present invention are:

[0019] High-performance sealant is used to seal the joints of steel plates. The N and O atoms on the side chains of the sealant contain lone pairs of electrons, which can transfer charge with the empty 3d orbitals of Fe atoms on the surface of the steel plate or form coordination. This allows the sealant to be adsorbed onto the surface of the steel plate and form an adsorption film, effectively blocking the entry of corrosive media and playing a role in corrosion inhibition. While ensuring adhesion, the sealant also effectively improves the corrosion resistance of the steel plate, thereby ensuring the safety and long-term stability of the steel structure. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the embodiments. Example 1

[0021] A sealant for joints in steel structures. The preparation steps include:

[0022] (1) Preparation of modified polysiloxane

[0023] A modified polysiloxane was dissolved in THF along with an appropriate mass of furfural, maintaining a molar ratio of amino to aldehyde groups of 1:1. Na₂SO₄ was added, and the mixture was stirred at room temperature for 24 hours. The Na₂SO₄ was removed by centrifugation, the solvent was removed by rotary evaporation, and the mixture was vacuum dried in an oven for 12 hours to obtain the modified polysiloxane. The modified polysiloxane has the following structure:

[0024]

[0025] In the formula, R is a methyl group; m=100, n=50.

[0026] (2) Preparation of sealant for steel structure joints

[0027] 50 parts of modified polysiloxane, 3 parts of silane oligomer, 30 parts of heavy calcium carbonate, 0.5 parts of thixotropic agent, 0.1 parts of hindered amine UV stabilizer, and 0.1 parts of antioxidant were vacuum-stirred at 120℃ for 1 hour. After natural cooling to room temperature, 0.05 parts of catalyst, 30 parts of methyltriethoxysilane, and 0.5 parts of 3-aminopropyltrimethoxysilane were added, and high-speed stirring was continued for 20 minutes. After uniform stirring, vacuum treatment was performed, and the mixture was then filled to obtain a steel structure joint sealant. Example 2

[0028] The preparation method of this embodiment is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0029] The modified polysiloxane used in this embodiment has the following structure:

[0030]

[0031] In the formula, R is a methyl group; m=10, n=50.

[0032] In this embodiment, 30 parts of modified polysiloxane, 3 parts of silane oligomer, 30 parts of silica powder, 0.5 parts of thixotropic agent, 0.1 parts of hindered amine UV stabilizer and 0.1 parts of antioxidant are used. The crosslinking agent is 30 parts of methyltriacetoxysilane, and the silane coupling agent is 1 part of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. Example 3

[0033] The preparation method of this embodiment is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0034] The modified polysiloxane used in this embodiment has the following structure:

[0035]

[0036] In the formula, R is ethyl; m=20, n=100.

[0037] In this embodiment, 30 parts of modified polysiloxane, 3 parts of silane oligomer, 40 parts of silica powder, 0.5 parts of thixotropic agent, 0.1 parts of hindered amine UV stabilizer and 0.1 parts of antioxidant are used. The crosslinking agent is 30 parts of methyltriacetoxysilane, and the silane coupling agent is 0.5 parts of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. Example 4

[0038] The preparation method of this embodiment is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0039] The modified polysiloxane used in this embodiment has the following structure:

[0040]

[0041] In the formula, R is n-propyl; m=100, n=20.

[0042] This embodiment uses 50 parts of modified polysiloxane, 3 parts of silane oligomer, 30 parts of calcium carbonate, 1 part of thixotropic agent, 0.1 part of hindered amine UV stabilizer and 0.1 part of antioxidant, 40 parts of methyltriacetoxysilane as crosslinking agent, and 2 parts of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane as silane coupling agent.

[0043] Comparative Example 1:

[0044] The preparation method of this comparative example is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0045] The modified polysiloxane used in this comparative example has the following structure:

[0046]

[0047] In the formula, R is a methyl group; m=200, n=50.

[0048] This comparative example uses 50 parts modified polysiloxane, 3 parts silane oligomer, 30 parts heavy calcium carbonate, 0.5 parts thixotropic agent, 0.1 parts hindered amine UV stabilizer and 0.1 parts antioxidant. The crosslinking agent is 30 parts methyltriethoxysilane; the silane coupling agent is 0.5 parts 3-aminopropyltrimethoxysilane.

[0049] Comparative Example 2:

[0050] The preparation method of this comparative example is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0051] The modified polysiloxane used in this comparative example has the following structure:

[0052]

[0053] In the formula, R is a methyl group; m=100, n=10.

[0054] This comparative example uses 50 parts modified polysiloxane, 3 parts silane oligomer, 30 parts heavy calcium carbonate, 0.5 parts thixotropic agent, 0.1 parts hindered amine UV stabilizer and 0.1 parts antioxidant. The crosslinking agent is 30 parts methyltriethoxysilane; the silane coupling agent is 0.5 parts 3-aminopropyltrimethoxysilane.

[0055] Comparative Example 3:

[0056] The preparation method of this comparative example is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0057] The modified polysiloxane used in this comparative example has the following structure:

[0058]

[0059] In the formula, R is a methyl group; m=10, n=50.

[0060] This comparative example uses 30 parts modified polysiloxane, 3 parts silane oligomer, 30 parts silica powder, 0.5 parts thixotropic agent, 30 parts methyltriacetoxysilane as crosslinking agent, and 1 part N-2-(aminoethyl)-3-aminopropyltrimethoxysilane as silane coupling agent.

[0061] Comparative Example 4:

[0062] The preparation method of this comparative example is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0063] The modified polysiloxane used in this comparative example has the following structure:

[0064]

[0065] In the formula, R is a methyl group; m=200, n=200.

[0066] This comparative example uses 30 parts modified polysiloxane, 3 parts silane oligomer, 30 parts silica powder, 0.5 parts thixotropic agent, 0.1 parts hindered amine UV stabilizer and 0.1 parts antioxidant, 30 parts methyltriacetoxysilane as crosslinking agent, and 1 part N-2-(aminoethyl)-3-aminopropyltrimethoxysilane as silane coupling agent.

[0067] Comparative Example 5:

[0068] The preparation method of this comparative example is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0069] The modified polysiloxane used in this comparative example has the following structure:

[0070]

[0071] In the formula, R is ethyl; m=20, n=0.

[0072] This comparative example uses 30 parts modified polysiloxane, 3 parts silane oligomer, 40 parts silica powder, 0.5 parts thixotropic agent, 0.1 parts hindered amine UV stabilizer and 0.1 parts antioxidant. The crosslinking agent is 30 parts methyltriacetoxysilane; the silane coupling agent is 0.5 parts N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

[0073] Comparative Example 6:

[0074] The preparation method of this comparative example is basically the same as that of Example 1, except for the selection of raw materials and the mass fraction of each raw material, as shown below.

[0075] The modified polysiloxane used in this comparative example has the following structure:

[0076]

[0077] In the formula, R is octadecyl; m=100, n=20.

[0078] This comparative example uses 50 parts of modified polysiloxane, 3 parts of silane oligomer, 30 parts of calcium carbonate, 1 part of thixotropic agent, 0.1 part of hindered amine UV stabilizer and 0.1 part of antioxidant, 40 parts of methyltriacetoxysilane as crosslinking agent, and 2 parts of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane as silane coupling agent.

[0079] The sealant from each embodiment and comparative example was uniformly applied to the steel surface to form tensile bonding specimens. After curing under standard conditions for 28 days, initial tensile bond and elongation at break tests were conducted according to standard GB / T 13477.8-2017 "Test Methods for Building Sealing Materials Part 8: Determination of Tensile Bond Properties". Tensile bond and elongation at break tests were also conducted on specimens after 720 hours of UV aging and 720 hours of damp heat aging. The test results are shown in Table 1.

[0080] Table 1. Performance test results of the colloids prepared in Examples 1-4 and Comparative Examples 1-6

[0081]

[0082] As can be seen from the data in Table 1, the sealants prepared in Examples 1-5 have significant advantages in adhesive performance and elongation at break compared to the comparative examples, and maintain stable aging resistance, demonstrating reliable long-term performance. The imine bonds on the side chains of the modified polysiloxane possess excellent coordination properties. Their N and O atoms pair with the empty d orbitals of Fe atoms, forming a relatively strong coordination effect. This allows the sealant to effectively adsorb onto the steel plate surface and form a film, thus inhibiting corrosion, preventing further metal corrosion, and improving the durability of the steel structure.

[0083] Compared with Example 1, the m value of the modified polysiloxane in Comparative Example 1 was too high, and the n value of the modified polysiloxane in Comparative Example 2 was too low. The content of imine bonds and metal coordination bonds formed in the colloidal system was low, and a dense adsorption film was not formed on the steel surface, resulting in poor overall durability.

[0084] Compared with Example 2, Comparative Example 3 did not contain light stabilizers and antioxidants, resulting in poorer overall durability.

[0085] Compared with Example 2, the modified polysiloxane molecular chain in Comparative Example 4 is too long, which reduces the degree of cross-linking of the system, significantly reduces the colloidal strength, and worsens the sealing performance.

[0086] Compared with Example 3, Comparative Example 5 does not contain imine bonds. Although a certain amount of antioxidants and light stabilizers were added, the UV aging resistance of the material was slightly improved. However, the colloid had no corrosion inhibition effect on the steel surface. After humid heat aging, the steel plate surface was severely corroded and the adhesion performance was poor.

[0087] Compared with Example 4, the modified polysiloxane in Comparative Example 6 has a longer side chain alkyl chain, which hinders the coordination of imine to a certain extent, reduces the coordination effect of the colloid on the steel plate surface, weakens the corrosion inhibition effect, and reduces the anti-aging ability, thus failing to meet the requirements of actual use.

[0088] In summary, within the scope of the formulation claimed in this invention, the sealant meets all performance requirements. When the formulation exceeds the scope of protection claimed in this invention, some properties of the sealant will be significantly deficient.

Claims

1. A high durability sealant for sealing a joint of a steel structural panel, characterized by The sealant comprises the following components in parts by weight: 30-50 parts modified polysiloxane, 1-6 parts silane oligomer, 30-60 parts inorganic filler, 0.1-1 part thixotropic agent, 0.01-0.2 parts catalyst, 30-60 parts crosslinking agent, 0.3-2 parts silane coupling agent, 0.1-0.5 parts light stabilizer, and 0.1-1 part antioxidant; the modified polysiloxane has a number-average molecular weight of 6000-20000 and has the following general formula: ； In the formula, R is any one of methyl, ethyl, n-propyl, and isopropyl; 10≤m≤100, 20≤n≤100, where m and n are both positive numbers.

2. The high-durability sealant for sealing joints in steel structure panels according to claim 1, characterized in that, The method for preparing the modified polysiloxane includes the following steps: Aminopropyl polysiloxane and furfural of appropriate mass were dissolved in tetrahydrofuran (THF), with the molar ratio of amino to aldehyde groups controlled at 1:

1. Anhydrous sodium sulfate (Na2SO4) was added, and the mixture was stirred at room temperature for 24 h. Na2SO4 was removed by centrifugation, solvent was removed by rotary evaporation, and the mixture was vacuum dried in an oven for 12 h to obtain modified polysiloxane.

3. The high-durability sealant for sealing joints in steel structure panels according to claim 1, characterized in that... The inorganic filler includes at least one of calcium carbonate and silica powder.

4. The high durability sealant for sealing a gap of a steel structural panel according to claim 1, characterized in that The catalyst is composed of one or more of dioctyltin diacetate, dioctyltin dilaurate, dioctyltin dioctanoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctanoate, isopropyl titanate, isobutyl titanate, and n-butyl titanate; the crosslinking agent is composed of one or more of methyltriacetoxysilane, ethyltriacetoxysilane, vinyltriacetoxysilane, tetraethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, or vinyltriethoxysilane.

5. The high-durability sealant for sealing joints in steel structure panels according to claim 1, characterized in that... The light stabilizer is composed of one or more of benzotriazole UV absorbers and hindered amine UV stabilizers.

6. A high durability sealant for sealing the seams of steel structural panels according to claim 1, characterized in that The silane coupling agent is composed of one or more of 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, or N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane.

7. A high durability sealant for sealing of structural steel panel joints according to any one of claims 1 to 6, characterized in that The sealant can improve the corrosion resistance of the steel surface and enhance its overall durability.

8. The application of a high-durability sealant for sealing steel structure panel joints according to any one of claims 1-7 in sealing steel structure panel joints.

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