Preparation method of titanium catalyst and application thereof in silicone sealant

Abstract

This invention relates to the field of titanium catalysts, addressing the problem that titanate catalysts cannot simultaneously possess both storage and catalytic performance. It provides a method for preparing a titanium catalyst and its application in organosilicon sealants. The method for preparing the titanium catalyst includes the following steps: A) adding titanate compounds to a reaction vessel under a nitrogen or inert gas atmosphere; B) slowly adding α-carbonylamine, heating and stirring the reaction, and distilling under reduced pressure until no distillate remains after the reaction is complete; the α-carbonylamine has the following structural formula: where R1 is an alkyl group with ≤4 carbon atoms and R2 is an alkyl group with ≤6 carbon atoms; C) adding a silane reagent to the reaction vessel, heating and stirring to obtain the final titanium catalyst. The prepared titanium catalyst is used in the production of dealcoholized silicone sealants, and the resulting sealant exhibits good performance in terms of surface drying time, de-tack time, and strength retention.

Description

Technical Field

[0001] This invention relates to the field of titanium catalysts, and in particular to a method for preparing a titanium catalyst and its application in organosilicon sealants. Background Technology

[0002] Silicone sealants are widely used in various fields due to their good weather resistance, electrical insulation, physiological compatibility, and high temperature resistance. Among them, de-alcoholized silicone sealants have advantages such as low odor and non-corrosiveness, and are increasingly used in the electronics, electrical appliances and construction industries.

[0003] The raw materials for preparing dealcohol-type silicone sealants mainly include base adhesive, crosslinking agent, catalyst, filler, and other additives. Catalysts can effectively shorten curing time. Commonly used catalysts are mainly organometallic titanium compounds, primarily divided into simple alkoxy titanates and titanium complexes containing chelating ligands. The chelating ligands are mainly dicarbonyl compounds. Alkoxy titanates have good catalytic activity but are prone to hydrolysis and difficult to store. Titanium complexes containing chelating ligands have relatively good stability due to the presence of the chelating ligands, but their catalytic activity varies depending on the chelating ligand. For example, patent CN103554172A describes the preparation of titanate chelates using isopropyl titanate, ethyl acetoacetate, and 1,3-propanediol as raw materials. This method has the advantages of readily available raw materials, easy process implementation, easy control of the production process, and reduction or avoidance of viscosity peaks. However, this catalyst has poor stability and requires strict storage conditions. Overall, existing titanate catalysts have not yet achieved a good balance between stability, preparation methods, storage, and catalytic performance, and cannot simultaneously possess the advantages of all aspects. Therefore, an ideal solution is needed. Summary of the Invention

[0004] To overcome the problem that titanate catalysts cannot simultaneously possess both storage and catalytic properties, this invention provides a method for preparing a titanium catalyst and its application in organosilicon sealants. The prepared titanium catalyst is used in the production of dealcoholized silicone sealants, and the resulting sealant exhibits good performance in terms of surface drying time, detack time, and strength retention.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a titanium catalyst includes the following steps:

[0007] A. Add titanate compounds to the reaction vessel under a nitrogen or inert gas atmosphere;

[0008] B. Slowly add α-carbonylamine, heat and stir to react, and after the reaction is complete, distill under reduced pressure until no distillate remains; the structural formula of the α-carbonylamine is: Where R1 is an alkyl group with ≤4 carbon atoms, and R2 is an alkyl group with ≤6 carbon atoms;

[0009] C. Add silane reagent to the reaction vessel, heat and stir to obtain the final titanium catalyst.

[0010] De-alcoholized silicone sealants cure gradually from the surface inwards with the help of trace amounts of moisture in the air. During the curing process, the silicon-oxygen bonds in the silicone prepolymer undergo hydrolysis with water molecules to generate alcohol molecules, while simultaneously releasing silicon-oxygen bonds to form a cross-linked network structure. The addition of a catalyst can accelerate the hydrolysis reaction and increase the curing speed. In the chelated titanium catalyst of this invention, the carbonyl group is connected to the nitrogen atom. On the one hand, the lone pair on N has a conjugation effect with C=O, which can improve molecular stability; on the other hand, the nitrogen-ketone structure has a good penetration-enhancing effect, accelerating the rate at which water enters the colloid, thereby increasing the curing speed. In addition, the chelated titanium catalyst of this invention has good compatibility with 107 glue (hydroxyl-terminated polydimethylsiloxane), which can avoid product scrap due to viscosity peaks during the production process of de-alcoholized silicone sealants.

[0011] Preferably, the inert gas in step A is argon.

[0012] Preferably, the titanate compound in step A is tetraisopropyl titanate, tetra-n-butyl titanate, or tetraethyl titanate. More preferably, it is tetraisopropyl titanate.

[0013] Preferably, in step B, R1 of the α-carbonylamine is one of methyl, ethyl, n-propyl, and n-butyl, more preferably methyl or ethyl; R2 is one of methyl, ethyl, n-propyl, and n-butyl, more preferably methyl, ethyl, or n-propyl.

[0014] Preferably, the slow dripping rate in step B is 1-5 drops / second.

[0015] Preferably, the heating temperature in step B is 60-70°C, and the reaction time is 1-4 hours.

[0016] Preferably, the temperature of vacuum distillation in step B is 30-60°C.

[0017] Preferably, the silane reagent in step C is one of methyltrimethoxysilane, methyltriethoxysilane, or methyltripropoxysilane. The combined use of titanate and silane reagent can produce a synergistic effect, significantly improving the efficacy.

[0018] Preferably, the heating temperature in step C is 30-50℃ and the heating time is 0.5-2h.

[0019] Preferably, the molar ratio of the silane reagent, α-carbonylamine, and titanate compound is (3-10):(1.5-2):1. More preferably, it is (4-7):2:1.

[0020] The present invention also provides the application of the titanium catalyst prepared by the above method in organosilicon sealants.

[0021] The beneficial effects of this invention are as follows: the titanium catalyst obtained, when used in the production of dealcoholized silicone sealant, exhibits good performance in terms of surface drying time, de-tack time, and re-tack. Unlike existing chelated titanium catalysts, the chelating ligand used in this method contains a nitrogen atom, and such ligands have a better stabilizing effect on the titanium catalyst. Detailed Implementation

[0022] The technical solution of the present invention will be further described below through specific embodiments.

[0023] In this invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the field. The methods in the embodiments, unless otherwise specified, are conventional methods in the field.

[0024] General Implementation Examples

[0025] A method for preparing a titanium catalyst includes the following steps:

[0026] Step 1: Under a nitrogen or inert gas atmosphere, add titanate compounds to the reaction vessel; the inert gas is preferably argon; the titanate compounds are preferably tetraisopropyl titanate, tetra-n-butyl titanate, or tetraethyl titanate.

[0027] Step 2: Slowly add α-carbonylamine dropwise to the reaction vessel from Step 1 at a rate of 1-5 drops / second, heat to 60-70°C and stir for 1-4 hours. After the reaction is complete, distill under reduced pressure at 30-60°C until no distillate remains. The structural formula of the α-carbonylamine is as follows: Wherein R1 is an alkyl group with ≤4 carbon atoms, preferably one of methyl, ethyl, n-propyl, and n-butyl; R2 is an alkyl group with ≤6 carbon atoms, preferably one of methyl, ethyl, n-propyl, and n-butyl.

[0028] Step 3: Next, add the silane reagent to the reaction vessel from Step 2, heat to 30-50℃ and stir for 0.5-2 hours to obtain the final titanium catalyst. The silane reagent is one of methyltrimethoxysilane, methyltriethoxysilane, or methyltripropoxysilane.

[0029] The molar ratio of silane reagent, α-carbonylamine and titanate compound is (3-10):(1.5-2):1, preferably (4-7):2:1.

[0030] Example 1

[0031] A method for preparing a titanium catalyst, comprising the following steps:

[0032] Under a nitrogen atmosphere, 28.42 g (0.1 mol) of tetraisopropyl titanate was added to a reactor; 23.03 g (0.2 mol) of 1-dimethylamino-2-butanone was added at a rate of 2 drops per second, and the mixture was heated and stirred at 60 °C for 2 h. The mixture was then distilled under reduced pressure at 40 °C until no distillate remained. Next, 3.6 g of methyltrimethoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 30 °C for 50 min to obtain the titanium catalyst. The yield of the titanium catalyst was 95%.

[0033] Example 2

[0034] A method for preparing a titanium catalyst, comprising the following steps:

[0035] Under an argon atmosphere, 56.84 g (0.2 mol) of tetraisopropyl titanate was added to a reactor; 45.2 g (0.35 mol) of 1-diethylamino-2-propanone was added at a rate of 2 drops per second, and the mixture was heated and stirred at 65 °C for 3 h. The mixture was then distilled under reduced pressure at 50 °C until no distillate remained. Next, 10.2 g of methyltrimethoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 30 °C for 1.5 h to obtain the titanium catalyst. The yield of the titanium catalyst was 93.6%.

[0036] Example 3

[0037] A method for preparing a titanium catalyst, comprising the following steps:

[0038] Under a nitrogen atmosphere, 42.63 g (0.15 mol) of tetraisopropyl titanate was added to a reactor; 30.35 g (0.3 mol) of 1-dimethylamino-2-propanone was added at a rate of 1 drop per second, and the mixture was heated and stirred at 60 °C for 4 h. The mixture was then distilled under reduced pressure at 60 °C until no distillate remained. Next, 9.6 g of methyltriethoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 40 °C for 2 h to obtain the titanium catalyst. The yield of the titanium catalyst was 96.4%.

[0039] Example 4

[0040] A method for preparing a titanium catalyst, comprising the following steps:

[0041] Under a nitrogen atmosphere, 136 g (0.4 mol) of tetrabutyl titanate was added to a reactor; 103.4 g (0.8 mol) of 1-diethylamino-2-propanone was added at a rate of 3 drops per second, and the mixture was heated and stirred at 70 °C for 3 h. The mixture was then distilled under reduced pressure at 50 °C until no distillate remained. Next, 25 g of methyltriethoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 30 °C for 30 min to obtain the titanium catalyst. The yield of the titanium catalyst was 94.8%.

[0042] Example 5

[0043] A method for preparing a titanium catalyst, comprising the following steps:

[0044] Under a nitrogen atmosphere, 102 g (0.3 mol) of tetrabutyl titanate was added to a reactor; 83.1 g (0.58 mol) of 1-diethylamino-2-butanone was added at a rate of 2 drops per second, and the mixture was heated and stirred at 70 °C for 4 h. The mixture was then distilled under reduced pressure at 55 °C until no distillate remained. Next, 20.3 g of methyltripropoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 30 °C for 1 h to obtain the titanium catalyst. The yield of the titanium catalyst was 96%.

[0045] Example 6

[0046] A method for preparing a titanium catalyst, comprising the following steps:

[0047] Under a nitrogen atmosphere, 45.6 g (0.2 mol) of tetraethyl titanate was added to a reactor; 51.68 g (0.4 mol) of 1-diethylamino-2-propanone was added at a rate of 3 drops per second, and the mixture was heated and stirred at 60 °C for 3 h. The mixture was then distilled under reduced pressure at 60 °C until no distillate remained. Next, 10 g of methyltripropoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 30 °C for 1.5 h to obtain the titanium catalyst. The yield of the titanium catalyst was 92.8%.

[0048] Example 7

[0049] A method for preparing a titanium catalyst, comprising the following steps:

[0050] Under a nitrogen atmosphere, 42.63 g (0.15 mol) of tetraisopropyl titanate was added to a reactor; 59.8 g (0.3 mol) of 1-dipropylamino-2-hexanone was added at a rate of 3 drops per second, and the mixture was heated and stirred at 60 °C for 3 h. The mixture was then distilled under reduced pressure at 50 °C until no distillate remained. Next, 10 g of methyltripropoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 30 °C for 1 h to obtain the titanium catalyst. The yield of the titanium catalyst was 89%.

[0051] Example 8

[0052] A method for preparing a titanium catalyst, comprising the following steps:

[0053] Under a nitrogen atmosphere, 42.63 g (0.15 mol) of tetraisopropyl titanate was added to a reactor; 59.8 g (0.3 mol) of 1-diethylamino-2-octanone was added at a rate of 3 drops per second, and the mixture was heated and stirred at 60 °C for 4 h. The mixture was then distilled under reduced pressure at 50 °C until no distillate remained. Next, 11 g of methyltripropoxysilane reagent was added to the reactor, and the mixture was heated and stirred at 30 °C for 1.5 h to obtain the titanium catalyst. The yield of the titanium catalyst was 85%.

[0054] Comparative Example 1

[0055] The difference from Example 1 is that the ligand used is different, and it is 1-diphenylamino-2-octanone.

[0056] A method for preparing a titanium catalyst, comprising the following steps:

[0057] Under a nitrogen atmosphere, 28.42 g (0.1 mol) of tetraisopropyl titanate was added to the reactor; 0.2 mol of 1-diphenylamino-2-octanone was added at a rate of 2 drops per second, and the mixture was heated and stirred at 60 °C for 2 h. The mixture was then distilled under reduced pressure at 40 °C until no distillate was obtained; 3.6 g of methyltrimethoxysilane reagent was then added to the reactor, and the mixture was heated and stirred at 30 °C for 50 min to obtain the titanium catalyst.

[0058] Comparative Example 2

[0059] The difference from Example 2 is that the reaction temperature of the titanate compound and the ligand is 90°C.

[0060] A method for preparing a titanium catalyst, comprising the following steps:

[0061] Under an argon atmosphere, 56.84 g (0.2 mol) of tetraisopropyl titanate was added to the reactor; 45.2 g (0.35 mol) of 1-diethylamino-2-propanone was added at a rate of 2 drops per second, and the mixture was heated and stirred at 90 °C for 3 h. The mixture was then distilled under reduced pressure at 50 °C until no distillate was obtained; 10.2 g of methyltrimethoxysilane reagent was then added to the reactor, and the mixture was heated and stirred at 30 °C for 1.5 h to obtain the titanium catalyst.

[0062] Comparative Example 3

[0063] The difference from Example 3 is that the molar ratio of titanate compound to ligand is 3:1.

[0064] A method for preparing a titanium catalyst, comprising the following steps:

[0065] Under a nitrogen atmosphere, 42.63 g (0.15 mol) of tetraisopropyl titanate was added to the reactor; 0.45 mol of 1-dimethylamino-2-propanone was added at a rate of 1 drop per second, and the mixture was heated and stirred at 60 °C for 4 h. The mixture was then distilled under reduced pressure at 60 °C until no distillate was obtained; 9.6 g of methyltriethoxysilane reagent was then added to the reactor, and the mixture was heated and stirred at 40 °C for 2 h to obtain the titanium catalyst.

[0066] Application examples

[0067] The titanium catalysts prepared by Examples 1-8 and Comparative Examples 1-3 above, and a catalyst S22 with good production performance in the prior art, were used to catalyze the reaction of methyltrimethoxysilane with hydroxyl-terminated polydimethylsiloxane. The performance of the catalysts was determined by measuring the curing rate and de-sticking time of the polymer.

[0068] The specific method is as follows: Take 500g of 107 adhesive (hydroxyl-terminated polydimethylsiloxane), 250g of white oil, and 1000g of calcium carbonate, stir evenly to obtain the base material, then add 10g of methyltrimethoxysilane and 6g of titanium catalysts 1-8 prepared in Examples 1-8 above or catalyst S22 with good production effect in the prior art to 500g of base material, stir evenly to obtain the sealant. Then test the performance of the sealant.

[0069] The experimental results are shown in Tables 1 and 2.

[0070] Table 1. Performance of titanium catalysts and catalyst S22 prepared in Examples 1-8

[0071]

[0072] Table 2. Catalytic results of titanium catalysts prepared in Comparative Examples 1-3

[0073] Catalyst number Comparative Example 1 Comparative Example 2 Comparative Example 3 Catalytic results In-cylinder curing of adhesive The surface of the rubber compound is very slow, and its strength is very low. In-cylinder curing of adhesive

[0074] As can be seen from the table above, the titanium catalyst prepared by this invention has a moderate surface drying time and de-sticking time, and the retention rate after aging of the adhesive strip is also good, indicating good overall catalytic activity. Furthermore, the catalyst exhibits good stability. In Comparative Example 1, the ligand structure in which N is linked to a benzene ring, compared to the example where N is linked to an alkyl group, resulted in an excessively fast catalytic rate, rendering the catalyst impractical. In Comparative Example 2, the ligand reaction temperature exceeded the preferred range, and in Comparative Example 3, the ligand dosage was outside the preferred range, resulting in poor catalyst performance. Therefore, only within the preferred range of this invention can optimal beneficial effects be obtained.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a titanium catalyst, characterized in that, Includes the following steps: A. Under a nitrogen or inert gas atmosphere, add titanate compounds to the reaction vessel, wherein the titanate compounds are tetraisopropyl titanate, tetra-n-butyl titanate, or tetraethyl titanate. B. Slowly add α-carbonylamine dropwise, heat and stir to react. After the reaction is complete, distill under reduced pressure until no distillate remains. The heating temperature is 60-70 °C. The structural formula of the α-carbonylamine is: Where R1 is an alkyl group with ≤4 carbon atoms and R2 is an alkyl group with ≤6 carbon atoms; C. Add silane reagent to the reaction vessel, heat and stir to obtain the final titanium catalyst; the molar ratio of silane reagent, α-carbonylamine and titanate compound is (3-10):(1.5-2):

1.

2. The preparation method according to claim 1, characterized in that, In step B, R1 of the α-carbonylamine is one of methyl, ethyl, n-propyl, and n-butyl, and R2 is one of methyl, ethyl, n-propyl, and n-butyl.

3. The preparation method according to claim 1, characterized in that, The slow dripping rate described in step B is 1-5 drops / second.

4. The preparation method according to claim 1, characterized in that, The reaction time described in step B is 1-4 hours.

5. The preparation method according to claim 1, characterized in that, The temperature for vacuum distillation in step B is 30-60℃.

6. The preparation method according to claim 1, characterized in that, The silane reagent mentioned in step C is one of methyltrimethoxysilane, methyltriethoxysilane, and methyltripropoxysilane.

7. The preparation method according to claim 1, characterized in that, The heating temperature in step C is 30-50 ℃ and the heating time is 0.5-2 h.

8. The application of a titanium catalyst prepared by any one of the preparation methods according to claims 1-7 in organosilicon sealants.

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