A cross-linking curing agent for dealcoholized silicone sealant and a preparation method thereof

Abstract

The application provides a cross-linking curing agent for dealcoholized silicone sealant and a preparation method thereof, the cross-linking curing agent comprises the following components in parts by weight: 55-75 parts of polymethyl triethoxysilane, 15-35 parts of orthosilicate, 1-2 parts of amino alkoxy silane, 4-6 parts of secondary amino bis trialkoxy silane, 1-2 parts of epoxy trialkoxy silane, 1.4-1.7 parts of acetyl ethyl acetate, 0.1-0.2 parts of anhydrous nickel chloride and 0.1-0.5 parts of organic tin catalyst. The cross-linking curing agent has the dual functions of traditional cross-linking agent and coupling agent, and has high stability and high performance. When applied to two-component alcohol type glue and alcohol type transparent glue, the preparation process of replacing alkoxyl-terminated 107 with conventional hydroxyl-terminated 107 can be realized, good storage period and preferable mechanical properties are ensured, and the final production, performance and cost are greatly optimized.

Description

Technical Field

[0001] This invention relates to the field of de-alcoholized silicone sealant technology, and particularly to a crosslinking curing agent for de-alcoholized silicone sealant and its preparation method. Background Technology

[0002] In methanol-removing transparent silicone sealants and two-component alcohol-based adhesive systems, organotin catalysis is currently the most commonly used method, rather than titanium catalysis. Methanol-removing transparent silicone sealants, due to their transparency requirements, cannot use titanium catalysis; two-component alcohol-based adhesives, on the other hand, require tin catalysis because titanium catalysis severely affects the overall curing effect of the adhesive, and the viscosity peak causes production difficulties. Furthermore, under ordinary methanol-removing crosslinking agents and tin catalysis, methanol-removing transparent silicone sealants have strict requirements on the selection of 107 adhesive. Extensive experimental data and professional publications have demonstrated that conventional hydroxyl-terminated 107 is highly prone to gelation and drying under these conditions, necessitating the use of alkoxy-terminated 107 as a base. However, compared to hydroxyl-terminated 107, the synthesis process of alkoxy-terminated 107 is more complex, and its commercial price is generally higher, ultimately leading to a significant increase in product cost. On the other hand, the same problem still exists in the preparation of two-component de-alcoholized silicone sealants. Although sometimes the B component can be replaced with silicone oil instead of 107, and combined with ordinary de-alcoholized crosslinking agents and tin catalysts to avoid the problem of gel drying, the two-component silicone sealant prepared based on silicone oil not only has certain limitations on the content of silicone oil, but also tends to seep oil and become sticky on the surface after a certain amount is exceeded. In addition, its mechanical properties and storage properties are poor. Summary of the Invention

[0003] This invention provides a crosslinking curing agent for de-alcoholized silicone sealants and its preparation method, aiming to solve the aforementioned problems existing in the background art.

[0004] To achieve the above objectives, embodiments of the present invention provide a crosslinking curing agent for de-alcoholized silicone sealants, comprising the following components by weight:

[0005] 55–75 parts polymethyltriethoxysilane, 15–35 parts orthosilicate, 1–2 parts aminoalkoxysilane, 4–6 parts secondary aminobistrialkoxysilane, 1–2 parts epoxytrialkoxysilane, 1.4–1.7 parts ethyl acetate, 0.1–0.2 parts anhydrous nickel chloride, and 0.1–0.5 parts organotin catalyst.

[0006] Preferably, the degree of polymerization of the polymethyltriethoxysilane is 3 to 6.

[0007] Preferably, the orthosilicate is at least one of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0008] Preferably, the aminoalkoxysilane is at least one selected from γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane, and amino-modified silane oligomers.

[0009] Preferably, the epoxytrialkoxysilane is at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0010] Preferably, the organotin catalyst is at least one of dibutyltin dilaurate and dibutyltin diacetate.

[0011] Preferably, the dealcoholized silicone sealant includes a two-component dealcoholized silicone sealant and a one-component dealcoholized transparent silicone sealant.

[0012] Based on a general inventive concept, embodiments of the present invention provide a method for preparing the above-mentioned crosslinking curing agent for de-alcoholized silicone sealants, comprising the following steps:

[0013] S1: Place 55-75 parts of polymethyltriethoxysilane and 15-35 parts of orthosilicate in a reaction vessel, add 1.4-1.7 parts of ethyl acetate and 0.1-0.2 parts of anhydrous nickel chloride in sequence, stir and heat to 60-70℃, react for 1-2 hours under dry nitrogen protection, cool and filter, and distill the filtrate under reduced pressure to obtain polymer A;

[0014] S2: Take 1-2 parts of epoxytrialkoxysilane and 0.1-0.5 parts of organotin catalyst and place them in another reaction vessel. Under nitrogen protection and stirring, heat to 80-90℃. Add 1-2 parts of aminoalkoxysilane dropwise within 1 hour. React for 2 hours and then distill under reduced pressure to obtain polymer B.

[0015] S3: Add polymer A and 4-6 parts of secondary aminobistrialkoxysilane sequentially to polymer B, stir under nitrogen protection, and keep the temperature at 80-90°C to further undergo random copolymerization. After reacting for 2-3 hours, filter by vacuum distillation to obtain the crosslinking curing agent.

[0016] This invention is based on the following principles: In the first step, polymethyltriethoxysilane, orthosilicate, and ethyl acetate are reacted with anhydrous nickel chloride as a catalyst, undergoing transesterification and chain extension reactions at a suitable temperature and for a sufficient time. The resulting polymer A is a siloxane copolymer with alkoxy-terminated high polymerization degree and acyl or alkoxy active functional groups on its side groups. Under the preferred weight proportions of this invention, polymer A has high purity. In the second step, polymer B is obtained by ring-opening polymerization of epoxytrialkoxysilane and aminoalkoxysilane under an organotin catalyst, resulting in a blend of polymers containing amino, epoxy, or hydroxyl active functional groups. In the third step, using secondary aminobistrialkoxysilane as an intermediate and the six alkoxy groups at both ends as "moving bridges," in the presence of organotin, at a suitable temperature and for a sufficient time, a random copolymerization reaction between polymer A and polymer B is further achieved, ultimately yielding a crosslinking curing agent.

[0017] The above-described solution of the present invention has the following beneficial effects:

[0018] The crosslinking curing agent of the present invention has the dual functions of a traditional crosslinking agent and a coupling agent, and has high stability and high performance. Especially when applied to two-component alcohol-based adhesives and alcohol-based transparent adhesives, it can realize the preparation process based on conventional hydroxyl-terminated 107 to replace alkoxy-terminated 107, and ensure good storage period and better mechanical properties. Ultimately, production performance and cost are greatly optimized. Detailed Implementation

[0019] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.

[0020] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0022] This invention addresses the existing problems by providing a crosslinking curing agent for de-alcoholized silicone sealants, comprising the following components by weight:

[0023] 55–75 parts polymethyltriethoxysilane, 15–35 parts orthosilicate, 1–2 parts aminoalkoxysilane, 1–2 parts epoxytrialkoxysilane, 1.4–1.7 parts ethyl acetate, 0.1–0.2 parts anhydrous nickel chloride, and 0.1–0.5 parts organotin catalyst.

[0024] Preferably, the degree of polymerization of the polymethyltriethoxysilane is 3 to 6.

[0025] Preferably, the orthosilicate is at least one of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0026] Preferably, the aminoalkoxysilane is at least one selected from γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane, and amino-modified silane oligomers.

[0027] Preferably, the epoxytrialkoxysilane is at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0028] Preferably, the organotin catalyst is at least one of dibutyltin dilaurate and dibutyltin diacetate.

[0029] Preferably, the dealcoholized silicone sealant includes a two-component dealcoholized silicone sealant and a one-component dealcoholized transparent silicone sealant.

[0030] Based on a general inventive concept, embodiments of the present invention provide a method for preparing the above-mentioned crosslinking curing agent for de-alcoholized silicone sealants, comprising the following steps:

[0031] S1: Place 55-75 parts of polymethyltriethoxysilane and 15-35 parts of orthosilicate in a reaction vessel, add 1.4-1.7 parts of ethyl acetate and 0.1-0.2 parts of anhydrous nickel chloride in sequence, stir and heat to 60-70℃, react for 1-2 hours under dry nitrogen protection, cool and filter, and distill the filtrate under reduced pressure to obtain polymer A;

[0032] S2: Take 1-2 parts of epoxytrialkoxysilane and 0.1-0.5 parts of organotin catalyst and place them in another reaction vessel. Under nitrogen protection and stirring, heat to 80-90℃. Add 1-2 parts of aminoalkoxysilane dropwise within 1 hour. React for 2 hours and then distill under reduced pressure to obtain polymer B.

[0033] S3: Add polymer A and 4-6 parts of secondary aminobistrialkoxysilane sequentially to polymer B, stir under nitrogen protection, and keep the temperature at 80-90°C to further undergo random copolymerization. After reacting for 2-3 hours, filter by vacuum distillation to obtain the crosslinking curing agent.

[0034] The following is a detailed description through specific embodiments.

[0035] Example 1

[0036] A method for preparing a dealcohol-free organosilicon crosslinking curing agent specifically includes the following steps:

[0037] S1: Take 55 parts of polymethyltriethoxysilane with a degree of polymerization of 3 and 35 parts of tetraethyl orthosilicate and place them in a reaction vessel. Add 1.4 parts of ethyl acetate and 0.1 parts of anhydrous nickel chloride in sequence. Stir and heat to 60-70°C. React for 1-2 hours under dry nitrogen protection. Cool and filter. Distill the filtrate under reduced pressure to obtain polymer A.

[0038] S2: Take 1 part of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.2 parts of dibutyltin dilaurate and place them in another reaction vessel. Under nitrogen protection and stirring, heat to 80-90℃. Add 1 part of a mixture of γ-aminopropyltrimethoxysilane and 1 part of amino-modified silane oligomer (Evonik 1146) dropwise over 1 hour. React for 2 hours and then distill under reduced pressure to obtain polymer B.

[0039] S3: Add polymer A and 5.3 parts of secondary aminobistrimethoxypropylsilane sequentially to polymer B, stir under nitrogen protection, keep the temperature constant to 80-90℃, react for 2-3 hours, and then filter by vacuum distillation to obtain crosslinking curing agent 1.

[0040] Example 2

[0041] A method for preparing a dealcohol-free organosilicon crosslinking curing agent specifically includes the following steps:

[0042] S1: Take 75 parts of polymethyltriethoxysilane with a degree of polymerization of 6 and 15 parts of methyl orthosilicate and place them in a reaction vessel. Add 1.7 parts of ethyl acetate and 0.2 parts of anhydrous nickel chloride in sequence. Stir and heat to 60-70°C. React for 1-2 hours under dry nitrogen protection. Cool and filter. Distill the filtrate under reduced pressure to obtain polymer A.

[0043] S2: Take 2 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.1 parts of dibutyltin dilaurate and place them in another reaction vessel. Under nitrogen protection and stirring, heat to 80-90℃. Add 1 part of a mixture of γ-aminopropyltriethoxysilane and 1 part of amino-modified silane oligomer (Jianghan New Materials JH-AP1231) dropwise over 1 hour. React for 2 hours and then distill under reduced pressure to obtain polymer B.

[0044] S3: Add polymer A and 4 parts of secondary aminobistrimethoxypropylsilane sequentially to polymer B, stir under nitrogen protection, keep the temperature at 80-90℃, react for 2-3 hours, and then filter by vacuum distillation to obtain crosslinking curing agent 2.

[0045] Example 3

[0046] A method for preparing a two-component, alcohol-free silicone sealant, specifically comprising the following steps:

[0047] (1) 100 parts by weight of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 20000 mpa.s at 25℃ were put into a planetary mixer, and 120 parts by weight of nano-active calcium carbonate were added in batches. The temperature was 50℃, the vacuum degree was maintained at -0.090 to -0.100 MPa, the speed was 20 Hz, and the mixture was stirred for 60 min to obtain component A.

[0048] (2) 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane at 20000 mpa.s and 120 parts by weight of heavy calcium carbonate were stirred and dispersed evenly. Vacuum was drawn, and 7.5 parts by weight of crosslinking curing agent 1 were added. The temperature was 50℃, the vacuum degree was maintained at -0.095 to -0.100 MPa, the speed was 20 Hz, and the mixture was stirred for 45 min to obtain component B.

[0049] (3) Mix component A and component B at a mass ratio of 1:1 to prepare a two-component de-alcoholized silicone sealant.

[0050] Comparative Example 1

[0051] A method for preparing a two-component, alcohol-free silicone sealant, specifically comprising the following steps:

[0052] (1) 100 parts by weight of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 20000 mpa.s at 25℃ were put into a planetary mixer, and 120 parts by weight of nano-active calcium carbonate were added in batches. The temperature was 50℃, the vacuum degree was maintained at -0.090 to -0.100 MPa, the speed was 20 Hz, and the mixture was stirred for 60 min to obtain component A.

[0053] (2) 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane at 20000 mpa.s and 120 parts by weight of heavy calcium carbonate were stirred and dispersed evenly. Vacuum was applied, and 5.5 parts by weight of polymethyltriethoxysilane were added. Vacuum stirring was carried out for 15 min. Then, 1.6 parts by weight of γ-aminopropyltriethoxysilane and 0.4 parts by weight of dibutyltin dilaurate were added. The vacuum degree was maintained at -0.095 to -0.100 MPa, the rotation speed was 20 Hz, and the mixture was stirred for 30 min to obtain component B.

[0054] (3) Mix component A and component B at a mass ratio of 1:1 to prepare a two-component de-alcoholized silicone sealant.

[0055] Comparative Example 2

[0056] A method for preparing a two-component, alcohol-free silicone sealant, specifically comprising the following steps:

[0057] (1) 100 parts by weight of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 20000 mpa.s at 25℃ were put into a planetary mixer, and 120 parts by weight of nano-active calcium carbonate were added in batches. The temperature was 50℃, the vacuum degree was maintained at -0.090 to -0.100 MPa, the speed was 20 Hz, and the mixture was stirred for 60 min to obtain component A.

[0058] (2) 100 parts by weight of 20000 mpa·s of trimekoxysilyl-terminated polydimethylsiloxane and 120 parts by weight of heavy calcium carbonate were stirred and dispersed evenly. Vacuum was drawn, and 5.5 parts by weight of polymethyltriethoxysilane were added. Vacuum stirring was carried out for 15 min. Then, 1.6 parts by weight of γ-aminopropyltriethoxysilane and 0.4 parts by weight of dibutyltin dilaurate were added. The vacuum degree was maintained at -0.095 to -0.100 MPa, the rotation speed was 20 Hz, and the mixture was stirred for 30 min to obtain component B.

[0059] (3) Mix component A and component B at a mass ratio of 1:1 to prepare a two-component de-alcoholized silicone sealant.

[0060] Example 4

[0061] A method for preparing a one-component, alcohol-free, transparent silicone sealant, specifically including the following steps:

[0062] 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane at 20000 mpa.s were added to a planetary mixer, and 8 parts by weight of fumed silica were added in batches. The mixture was slowly vacuumed and stirred until evenly dispersed. Then, 8 parts by weight of crosslinking curing agent 2 were added. The temperature was 50℃, the vacuum degree was maintained at -0.095 to -0.100 MPa, the speed was 20 Hz, and the mixture was stirred for 45 min to obtain a one-component de-alcoholized transparent silicone sealant.

[0063] Comparative Example 3

[0064] A method for preparing a one-component, alcohol-free, transparent silicone sealant, specifically including the following steps:

[0065] 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane at 20000 mpa.s were added to a planetary mixer, and 8 parts by weight of fumed silica were added in batches. The mixture was slowly vacuumed and stirred until evenly dispersed. Then, 5.5 parts by weight of polymethyltriethoxysilane were added and stirred under vacuum for 15 min. Then, 1.6 parts by weight of γ-aminopropyltriethoxysilane and 0.4 parts by weight of dibutyltin dilaurate were added. The vacuum was maintained at -0.095 to -0.100 MPa and the speed was 20 Hz. The mixture was stirred for 30 min to obtain a one-component de-alcoholized transparent silicone sealant.

[0066] Comparative Example 4

[0067] A method for preparing a one-component, alcohol-free, transparent silicone sealant, specifically including the following steps:

[0068] 100 parts by weight of 20000 mpa·s of trialkoxysilyl-terminated polydimethylsiloxane were added to a planetary mixer, and 8 parts by weight of fumed silica were added in batches. The mixture was slowly vacuumed and stirred until evenly dispersed. Then, 5.5 parts by weight of polymethyltriethoxysilane were added and stirred under vacuum for 15 min. Then, 1.6 parts by weight of γ-aminopropyltriethoxysilane and 0.4 parts by weight of dibutyltin dilaurate were added. The vacuum was maintained at -0.095 to -0.100 MPa and the speed was 20 Hz. The mixture was stirred for 30 min to obtain a one-component de-alcoholized transparent silicone sealant.

[0069] The physical properties of Examples 3-4 and Comparative Examples 1-4 were tested, and the results are shown in Table 1 below.

[0070] Table 1

[0071]

[0072]

[0073] As shown in Table 1, Examples 3, 1, and 2 are all two-component de-alcoholized silicone sealants, but the final results differ significantly. Comparative Example 1 uses hydroxyl-terminated 107 as a base, which is completely infeasible with conventional de-alcoholized crosslinking agents, coupling agents, and organotin catalysts. Example 3, however, uses hydroxyl-terminated 107 as a base, and its preparation process, combined with a de-alcoholized silicone crosslinking curing agent provided by this invention, is successful. Furthermore, compared to the preparation process of Comparative Example 2 using alkoxy-terminated 107, the two-component de-alcoholized silicone sealant prepared in Example 3 not only has good adhesion but also better shelf life and mechanical properties. Example 4 Comparative Examples 3 and 4 both involve the preparation process of a single-component, alcohol-terminated transparent silicone sealant, but the final results differ significantly. Comparative Example 3, using hydroxyl-terminated 107 as a base, combined with fumed silica, conventional alcohol-terminated crosslinking agents, coupling agents, and organotin catalysts, is a completely impractical preparation process. In contrast, Example 4, using hydroxyl-terminated 107 as a base, combined with fumed silica and the alcohol-terminated silicone crosslinking curing agent provided by this invention, is a feasible preparation process. Furthermore, compared to Comparative Example 4, which uses alkoxy-terminated 107 as a base, the single-component, alcohol-terminated transparent silicone sealant prepared in Example 4 exhibits good adhesion, better shelf life, and superior mechanical properties.

[0074] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A crosslinking curing agent for a de-alcoholized silicone sealant based on hydroxyl-terminated 107 adhesive, characterized in that, Based on parts by weight, it includes the following components: 55-75 parts of polymethyltriethoxysilane with a degree of polymerization of 3-6, 15-35 parts of orthosilicate, 1-2 parts of aminoalkoxysilane, 4-6 parts of secondary aminobistrialkoxysilane, 1-2 parts of epoxytrialkoxysilane, 1.4-1.7 parts of ethyl acetate, 0.1-0.2 parts of anhydrous nickel chloride, and 0.1-0.5 parts of organotin catalyst; The de-alcoholized silicone sealant includes a two-component de-alcoholized silicone sealant and a one-component de-alcoholized transparent silicone sealant; The preparation method of the crosslinking curing agent includes the following steps: S1: Take 55-75 parts of polymethyltriethoxysilane with a degree of polymerization of 3-6 and 15-35 parts of orthosilicate and place them in a reaction vessel. Add 1.4-1.7 parts of ethyl acetate and 0.1-0.2 parts of anhydrous nickel chloride in sequence. Stir and heat to 60-70 °C. React under dry nitrogen protection for 1-2 h. Cool and filter. Distill the filtrate under reduced pressure to obtain polymer A. S2: Take 1-2 parts of epoxytrialkoxysilane and 0.1-0.5 parts of organotin catalyst and place them in another reactor. Under nitrogen protection and stirring, heat to 80-90 °C. Add 1-2 parts of aminoalkoxysilane dropwise within 1 h. React for 2 h and then distill under reduced pressure to obtain polymer B. S3: Add polymer A and 4-6 parts of secondary aminobistrialkoxysilane sequentially to polymer B, stir under nitrogen protection, and keep the temperature at 80-90 °C to allow polymer A and polymer B to undergo random copolymerization. After reacting for 2-3 h, filter by vacuum distillation to obtain the crosslinking curing agent.

2. The crosslinking curing agent for a de-alcoholized silicone sealant based on hydroxyl-terminated 107 adhesive according to claim 1, characterized in that, The orthosilicate is tetraethyl orthosilicate.

3. The crosslinking curing agent for a de-alcoholized silicone sealant based on hydroxyl-terminated 107 adhesive according to claim 1, characterized in that, The aminoalkoxysilane is at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane, and amino-modified silane oligomers.

4. The crosslinking curing agent for a de-alcoholized silicone sealant based on hydroxyl-terminated 107 adhesive according to claim 1, characterized in that, The epoxy-trialkoxysilane is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

5. The crosslinking curing agent for a de-alcoholized silicone sealant based on hydroxyl-terminated 107 adhesive according to claim 1, characterized in that, The organotin catalyst is dibutyltin dilaurate.

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