Organic tin catalyst and preparation method thereof

Abstract

The invention discloses a preparation method of an organic tin catalyst, and the organic tin catalyst comprises the following components in parts by weight: 100 parts by mass of tributyl citrate, 60-100 parts by mass of citric acid, 80-110 parts by mass of dibutyltin oxide, 1-2 parts by mass of a neutralizer and 2-5 parts by mass of a coupling agent.The invention provides the organic tin catalyst and the preparation method thereof. The catalyst is good in catalytic effect, fast in deep curing and good in heat resistance.

Description

Technical Field

[0001] The present invention relates to an organotin catalyst and a preparation method thereof, and pertains to the technical field of organotin catalyst synthesis. Background Art

[0002] Organotin compounds are metal-organic compounds formed by the direct combination of tin and carbon elements. The general formula is RnSnX4-(n = 1 - 4, R is an alkyl or aryl group). There are two categories: alkyltin compounds and aryl compounds. Its basic structures include mono-substituted, di-substituted, tri-substituted, and tetra-substituted forms (referring to the number of Rs). 10 - 20% of the tin production is used for the synthesis of organotin compounds. Organotin catalysts are usually used in the production of products such as polyurethane and room temperature vulcanized silicone rubber, and are widely used especially in industries such as polyurethane foam, coatings, room temperature vulcanized silicone rubber, elastomers, adhesives, and resins. Patent CN107473955A discloses a preparation method of stannous octoate T-9. This preparation method is simple and easy to operate, has few steps, and has a high content of divalent tin in the tin solution, a high content of stannous octoate in the product, is stable, has strong antioxidant properties, no loss, no peculiar smell, good catalytic effect, low cost, and low risk. However, the catalytic effect of stannous octoate has a delay, and in actual application, it often fails to meet the construction requirements.

[0003] Patent CN111303203A discloses a synthesis process of dibutyltin dilaurate, which pertains to the technical field of dibutyltin dilaurate synthesis. To solve the problem that after the synthesis of existing dibutyltin dilaurate, it is mostly light yellow, and when preparing colorless materials such as transparent plastics or films, color differences are likely to occur, affecting the finished product effect. The process flow is complex and long, and there is a large amount of alkaline wastewater.

[0004] Patent CN104497036A specifically discloses a preparation process of dibutyltin diacetate. The product of the present invention has complete reaction, low production cost, and good product quality. However, the application range of dibutyltin diacetate is relatively narrow and it has relatively large corrosiveness. Summary of the Invention

[0005] The present invention designs an organotin catalyst aiming at the above technical drawbacks. Its raw materials include tributyl citrate, citric acid, dibutyltin oxide, neutralizing agent, and coupling agent. The present invention provides an organotin catalyst and a preparation method thereof. This catalyst has good catalytic effect, fast deep curing, and has good heat resistance.

[0006] The present invention is realized through the following technical solutions: A preparation method of an organotin catalyst, characterized by comprising the following steps: (1) At room temperature, mix tributyl citrate, citric acid, and dibutyltin oxide, then evacuate to vacuum, and carry out a low-boiling point removal reaction under heating until the solution becomes clear; (2) After cooling, a neutralizing agent is added and mixed evenly for reaction; (3) After adding a coupling agent and mixing, vacuum is pumped and stirring reaction is carried out to obtain.

[0007] In the step (1), the added mass parts of each raw material are: 100 mass parts of tributyl citrate; 60 - 100 mass parts of citric acid; 80 - 110 mass parts of dibutyltin oxide.

[0008] The content of tributyl citrate is more than 99%; The content of citric acid is more than 99% and does not contain water; For the dibutyltin oxide, the tin content is more than 46%; In the step (1), vacuum is pumped to a vacuum degree less than -0.098 Mpa, heated to 120°C - 150°C, and low-boiling reaction is carried out for 1 - 3 hours.

[0009] In this application, tributyl citrate is used as a reaction solvent.

[0010] In the step (2), the temperature is reduced to 80°C - 100°C, 1 - 2 parts of a neutralizing agent are added, and the reaction is carried out for 40 min - 1 h.

[0011] The neutralizing agent is one or a mixture of sodium hydroxide, potassium hydroxide, and sodium methoxide solution.

[0012] The purpose of adding the neutralizing agent is to consume the residual citric acid in the system, and the pH value after neutralization is 6 - 7.

[0013] In the step (3), after adding 2 - 5 parts of a coupling agent, vacuum is pumped to a vacuum degree less than -0.098 Mpa, and stirring reaction is carried out for 30 min - 1 h.

[0014] The coupling agent is one or a mixture of two of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0015] Adding the coupling agent firstly plays the role of chemical water removal, and secondly provides an alkaline environment for the system to improve the catalytic efficiency.

[0016] Application of the described organotin catalyst in the preparation of sealant.

[0017] It includes the following steps: at room temperature, after vacuum degassing 107 rubber, nitrogen is introduced, methyl tributanone oxime silane is added, and vacuum stirring is carried out; under nitrogen introduction, fumed silica is added, and vacuum stirring is carried out; under nitrogen introduction, a coupling agent and an organotin catalyst are added, and vacuum stirring is carried out to obtain a sealant.

[0018] Compared with the prior art, the technical solution features and preparation of the present invention mainly have the following three points: 1. The present invention uses tributyl citrate as a chelating agent to reduce the problem of the tin catalyst becoming ineffective after long-term storage or aging, and improve the storage performance of the product.

[0019] 2. The present invention uses a coupling agent as a water remover, which can exist in the catalyst for a long time and improve the storage period of the catalyst.

[0020] 3. The catalytic effect of this catalyst is moderate. During the curing process, due to its special structure, the hydroxyl structure will bring moisture into the interior, improving the deep curing performance. Specific Embodiments

[0021] The following will further elaborate on the technical solution of the present invention in combination with examples: The composition components and mass fractions of the organotin catalyst of the present invention are shown in Table 1 in detail; Taking the components of No. 1 in Table 1 as an example, the preparation method of the organotin catalyst is described in detail as follows: At room temperature, 50 g of tributyl citrate, 40 g of citric acid, and 52 g of dibutyltin oxide are put into a conical flask and mixed evenly, heated to 120 °C, the vacuum degree is less than -0.098 Mpa, and dehydrated for two hours until the solution becomes clear; cooled to 50 °C, 1 g of sodium hydroxide is added to the conical flask, evacuated for 40 minutes, and the vacuum degree is less than -0.098 Mpa; 2 g of KH-550 is added to the conical flask and mixed evenly, evacuated for 30 minutes, and the vacuum degree is less than -0.098 Mpa, and then cooled to 40 °C, discharged and bottled to obtain the organotin catalyst.

[0022] The method for preparing the sealant is as follows: At room temperature, 300 g of 107 glue with a viscosity of 80,000 is added to a planetary mixer, vacuum degassed, the vacuum degree < -0.09 Mpa, and stirred for 10 minutes; nitrogen is introduced, 15 g of methyltributanoneoxime silane is added, and vacuum stirred for 10 minutes, the vacuum degree is < -0.09 Mpa; nitrogen is introduced, 30 g of fumed silica is added, stirred for 1 minute, and then vacuum stirred for 30 minutes, the vacuum degree < -0.09 Mpa; nitrogen is introduced, 5 g of KH-550 and 0.1 g of organotin catalyst are added, and vacuum stirred for 20 minutes, the vacuum degree < -0.09 Mpa; discharged and bottled.

[0023] Aging standard: The bottled stick glue (300 ml) is placed in an oven at 100 °C for 7 days, and after 7 days, it is placed under standard conditions for 24 hours and then sampled.

[0024] All detections and maintenance are carried out under standard conditions, and the standard conditions are room temperature 23 °C ± 2 °C and humidity 50% ± 5%.

[0025] The following table 1 shows the test results of various properties of sealants prepared with different catalysts. The mechanical properties were tested in accordance with GB / T 13477.8.

[0026] As can be seen from Table 1, the catalyst of the present invention has good deep curing performance and aging resistance during actual application.

[0027] Table 1 Test results of sealants prepared with different catalysts

Claims

1. A preparation method of an organotin catalyst, characterized in that, It includes the following steps: (1) At room temperature, mix tributyl citrate, citric acid, and dibutyltin oxide, then evacuate, and conduct a low-boiling-point removal reaction under heating until the solution becomes clear; (2) After cooling, add a neutralizing agent and mix evenly for reaction; (3) Add a coupling agent and mix, then evacuate and stir for reaction to obtain the product.

2. The preparation method of the organotin catalyst according to claim 1, characterized in that, In step (1), the added mass parts of each raw material are: 100 mass parts of tributyl citrate; 60 - 100 mass parts of citric acid; 80 - 110 mass parts of dibutyltin oxide.

3. The preparation method of the organotin catalyst according to claim 1, characterized in that, In step (1), evacuate to a vacuum degree less than -0.098 Mpa, heat to 120°C - 150°C, and conduct the low-boiling-point removal reaction for 1 - 3 hours.

4. The preparation method of the organotin catalyst according to claim 3, characterized in that, In step (2), cool to 80°C - 100°C, add 1 - 2 parts of the neutralizing agent, and react for 40 min - 1 h.

5. The preparation method of the organotin catalyst according to claim 4, wherein, The neutralizing agent is one or a mixture of sodium hydroxide, potassium hydroxide, and sodium methoxide solution.

6. The preparation method of the organotin catalyst according to claim 1, wherein In step (3), after adding 2 - 5 parts of the coupling agent, evacuate to a vacuum degree less than -0.098 Mpa, and stir for reaction for 30 min - 1 h.

7. The preparation method of the organotin catalyst according to claim 6, characterized in that, The coupling agent is one or a mixture of two of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

8. An organotin catalyst, characterized in that, It is prepared by using the method described in any one of claims 1 - 7.

9. Use of the organotin catalyst described in claim 8 in the preparation of sealant.

10. The application according to claim 9, wherein It includes the following steps: At room temperature, after vacuum degassing 107 rubber, introduce nitrogen, add methyltributanone oxime silane, and stir under vacuum; introduce nitrogen and add fumed silica, and stir under vacuum; introduce nitrogen and add a coupling agent and an organotin catalyst, evacuate and stir to obtain the sealant.

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