A method of controlling the color of sulfur-containing silane coupling agents

Abstract

The application provides a method for controlling the colority of a sulfur-containing silane coupling agent. The method comprises the following steps: adding a composite antioxidant to the sulfur-containing silane coupling agent and stirring until uniform; the composite antioxidant is composed of a primary antioxidant and an auxiliary antioxidant; and the mass of the composite antioxidant added is 5-20 ‰ of the mass of the sulfur-containing silane coupling agent. The method effectively solves the problems of red color or deep yellow color, precipitation or stratification of the sulfur-containing silane coupling agent Si69 during storage, and effectively prolongs the storage period of the sulfur-containing silane coupling agent Si69.

Description

Technical Field

[0001] This invention relates to a method for controlling the color of sulfur-containing silane coupling agents, belonging to the field of organic chemistry technology. Background Technology

[0002] Sulfur-containing silane coupling agents are essential additives in the vulcanization process of high-grade natural and synthetic rubber products. Si69, a sulfur-containing silane coupling agent used as a coupling agent, softener, and reinforcing agent in raw rubber, is widely applied in the rubber industry. Si69 not only improves the surface activity of silica and carbon black in rubber, enhancing the dynamic bending properties of vulcanized rubber, but also balances the vulcanization system and strengthens the adhesion between organic and inorganic substances. In recent years, Si69 has also demonstrated excellent performance in metal corrosion protection surface treatment, leading to a significant increase in interest in this type of sulfur-containing silane coupling agent.

[0003] With the gradual expansion of the automotive market, the usage of tires is also increasing, leading to a growing demand for sulfur-containing silanes, especially high-quality ones. In recent years, continuous exploration of Si69 applications has revealed its potential in areas such as aluminum alloy surface protection, electronic and electrical chemical products, mesoporous materials with special morphologies, special processing and precision casting, preparation of long-chain compounds containing S and Si, and synthesis of textile printing and dyeing auxiliaries. These fields also place higher demands on the quality of Si69 products, particularly regarding color, odor, stability, purity, average sulfur content, and the sulfur structure and distribution within the molecule.

[0004] Currently, the synthesis methods for Si69 are quite mature, mainly divided into direct synthesis, organic solvent synthesis, and phase transfer catalysis. Direct synthesis and organic solvent synthesis suffer from unresolved problems such as complex conditions requiring nitrogen protection, generation of hazardous hydrogen gas, difficulty in controlling reaction temperature, environmental unfriendliness, and high equipment requirements. Furthermore, the products from direct synthesis and organic solvent synthesis after vacuum distillation are reddish or dark yellow in color, and some product decomposes during distillation, leading to unstable average sulfur content, precipitation, and even stratification during storage, affecting quality and leading to their gradual industrial obsolescence. Phase transfer catalysis (aqueous phase synthesis) has gained increasing attention and has become the mainstream industrial production method. Unfortunately, the synthesis of Si69 using phase transfer catalysis still faces a series of problems, including hydrolysis and abnormal color changes. During the phase separation process of the silane coupling agent Si69, excessive impurities inevitably remain in the oil phase, causing discoloration, precipitation, and other quality problems in the final product.

[0005] Numerous patent documents have reported solutions to the storage stability problem of sulfur-containing silane coupling agents. For example, Chinese patent document CN208470517 U reports a storage device with high sealing performance, solving the problem of hydrolysis and deterioration of organosilane coupling agents due to poor sealing during filling and storage. Chinese patent document CN214004478 U provides an automated production device that facilitates the appearance purification of polysulfide silane coupling agents, solving the problem of residual solid impurities such as sodium chloride and sulfur that may exist in polysulfide silane coupling agents, and minimizing the generation of by-products. European patent EP3838905A1 reports a method of using carrier steam distillation and / or ozone treatment to remove degradation products of phase transfer catalysts, thereby improving storage stability (including color and sulfur distribution) and achieving the goal of improving product quality. Although the above methods have solved a series of problems in the synthesis of sulfur-containing silane coupling agents by phase transfer catalysis, these methods have high equipment requirements and cumbersome processes, increasing product manufacturing costs.

[0006] Therefore, there is an urgent need to develop a method that can effectively control the color of sulfur-containing silane coupling agents and improve their storage stability. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for controlling the color of sulfur-containing silane coupling agents. The method of this invention effectively solves the problems of sulfur-containing silane coupling agent Si69 turning reddish or dark yellow, or exhibiting precipitation or stratification during storage, and effectively extends the shelf life of sulfur-containing silane coupling agent Si69.

[0008] To solve the above problems, the present invention adopts the following technical solution:

[0009] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0010] Add a composite antioxidant to the sulfur-containing silane coupling agent and stir until homogeneous; the composite antioxidant consists of a primary antioxidant and an auxiliary antioxidant, and the mass of the composite antioxidant added is 5-20‰ of the mass of the sulfur-containing silane coupling agent.

[0011] According to a preferred embodiment of the present invention, the mass of the composite antioxidant added is 8 to 15‰ of the mass of the sulfur-containing silane coupling agent.

[0012] According to a preferred embodiment of the present invention, the mass ratio of the primary antioxidant to the secondary antioxidant in the composite antioxidant is 1 to 5:1.

[0013] According to a preferred embodiment of the present invention, the primary antioxidant is a phenolic antioxidant, which is one or more of monophenolic antioxidants, bisphenolic antioxidants, and polyphenolic antioxidants.

[0014] More preferably, the monophenolic antioxidant is one or more of β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester (antioxidant 1076), 2,6-di-tert-butyl-p-cresol (BHT), and propyl gallate.

[0015] More preferably, the bisphenol antioxidant is one or both of 2,2'-methylenebis-(4-methyl-6-tert-butylphenol) (antioxidant 2246) and di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide (antioxidant 300).

[0016] More preferably, the polyphenolic antioxidant is one or two of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010) and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (antioxidant 1098).

[0017] According to a preferred embodiment of the present invention, the auxiliary antioxidant is one or more of the following: di(octadecyl)thiodipropionate (antioxidant DSTP), 2,2-bis[[3-(dodecylthio)-propionyloxy]methyl]-1,3-propanediol ester (antioxidant TH-412S), di(tetrazol)thiodipropionate, dilauryl thiodipropionate (antioxidant DLTDP), 4,4'-dithiobis(6-tert-butyl-2-methylphenol), 4,4'-thiobis(6-tert-butyl-m-cresol), tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(octadecyl) pentaerythritol diphosphite, and bis(2,4-dicumylphenyl) pentaerythritol diphosphite.

[0018] According to a preferred embodiment of the present invention, the sulfur-containing silane coupling agent is sulfur-containing silane coupling agent Si69, which is prepared by phase transfer catalysis. The preparation method is existing technology and can be referred to Chinese patent document CN112047975A.

[0019] According to a preferred embodiment of the present invention, the stirring speed is 3000-5000 r / min, and the stirring time is 10-20 min.

[0020] The technical features and beneficial effects of this invention are as follows:

[0021] 1. This invention selects a specific composite antioxidant as an additive, effectively solving the problems of sulfur-containing silane coupling agent Si69 turning reddish or dark yellow, and exhibiting precipitation or stratification during storage, thus improving product quality and enhancing the storage stability of sulfur-containing silane coupling agents. Simultaneously, it provides quality assurance for downstream applications of sulfur-containing silane coupling agents. In this invention, it is necessary to ensure that the amount of composite antioxidant added and the ratio of primary to secondary antioxidants within the composite antioxidant are within the range specified in this invention in order to control the color of the sulfur-containing silane coupling agent and improve its storage stability.

[0022] 2. The processing method of the present invention is effective, simple to operate, does not require specific equipment or complex procedures, has low production costs, and has potential application value in the industrial field.

[0023] 3. This invention improves the storage stability of sulfur-containing silane coupling agents by adding composite antioxidants without affecting their application performance. Rubber application performance tests show that the sulfur-containing silane coupling agent Si69 with added composite antioxidants exhibits comparable application performance to normal Si69 in various aspects, such as vulcanization resistance, scorch resistance, Mooney resistance, mechanical properties, DIN abrasion resistance, and DMA; its aging resistance is enhanced, thus improving the aging resistance of the filler to a certain extent. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0026] The sulfur-containing silane coupling agent Si69 bis-[3-(triethoxysilane)propyl]-tetrasulfide used in the examples was prepared by phase transfer catalysis, and the preparation method is referred to Example 6 of Chinese Patent Document CN112047975A.

[0027] Example 1

[0028] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0029] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide at room temperature for later use; weigh 1.2g (6‰) of the main antioxidant β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester and weigh 0.4g (2‰) of the auxiliary antioxidant di(octadecyl)thiodipropionate for later use;

[0030] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0031] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested with an iron-cobalt colorimeter, showing the following iron-cobalt color numbers:

[0032] Initial display of iron-cobalt color code: 5.8;

[0033] After 10 weeks, the iron-cobalt color code will be 6.0.

[0034] After 16 weeks, the iron-cobalt color code will be 6.5.

[0035] After 24 weeks, the iron-cobalt color code will be 6.7.

[0036] Example 2

[0037] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0038] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide at room temperature for later use; weigh 2.0g (10‰) of the main antioxidant 2,6-di-tert-butyl-p-cresol and weigh 0.6g (3‰) of the auxiliary antioxidant dilaurate thiodipropionate for later use.

[0039] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0040] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0041] Initial display of iron-cobalt color code: 5.8;

[0042] After 10 weeks, the iron-cobalt color code will be displayed as 6.1.

[0043] After 16 weeks, the iron-cobalt color code will be 6.6.

[0044] The iron-cobalt color code 7.1 will be displayed after 24 weeks.

[0045] Example 3

[0046] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0047] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide at room temperature for later use; weigh 1.2g (6‰) of the main antioxidant 2,2'-methylene bis-(4-methyl-6-tert-butylphenol) and weigh 0.6g (3‰) of the auxiliary antioxidant tris(2,4-di-tert-butylphenyl) phosphite for later use;

[0048] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0049] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0050] Initial display of iron-cobalt color code: 5.8;

[0051] After 10 weeks, the iron-cobalt color code will be 6.2.

[0052] After 16 weeks, the iron-cobalt color code is displayed as 6.8.

[0053] The iron-cobalt color code will be displayed after 24 weeks: 7.7.

[0054] Example 4

[0055] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0056] (1) Weigh 190g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide at room temperature for later use; weigh 2.85g (15‰) of the primary antioxidant di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide and 0.57g (3‰) of the secondary antioxidant 4,4'-thiobis(6-tert-butyl-m-cresol) for later use;

[0057] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0058] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0059] Initial display of iron-cobalt color code: 5.8;

[0060] After 10 weeks, the iron-cobalt color code will be 6.2.

[0061] After 16 weeks, the iron-cobalt color code is displayed as 6.7.

[0062] The iron-cobalt color code 7.2 will be displayed after 24 weeks.

[0063] Example 5

[0064] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0065] (1) Weigh 250g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide at room temperature for later use; weigh 1.25g (5‰) of the primary antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] and weigh 1.0g (4‰) of the secondary antioxidant bisoctadecyl pentaerythritol diphosphite for later use;

[0066] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0067] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0068] Initial display of iron-cobalt color code: 5.8;

[0069] After 10 weeks, the iron-cobalt color code will be 6.2.

[0070] After 16 weeks, the iron-cobalt color code is displayed as 6.8.

[0071] After 24 weeks, the iron-cobalt color code will be 7.5.

[0072] Example 6

[0073] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0074] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide solution at room temperature for later use; weigh 2.0g (10‰) of the main antioxidant N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine and 0.6g (3‰) of the auxiliary antioxidant di(octadecyl)thiodipropionate for later use;

[0075] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0076] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0077] Initial display of iron-cobalt color code: 5.8;

[0078] After 10 weeks, the iron-cobalt color code will be 6.2.

[0079] After 16 weeks, the iron-cobalt color code is displayed as 6.8.

[0080] After 24 weeks, the iron-cobalt color code will be 7.6.

[0081] Comparative Example 1

[0082] A method for controlling the color of sulfur-containing silane coupling agents is as described in Example 1, except that no composite antioxidant is added.

[0083] After initial placement, 10 weeks, 16 weeks, and 24 weeks, the iron-cobalt color code was tested using an iron-cobalt colorimeter, showing the following iron-cobalt color codes:

[0084] Initial display of iron-cobalt color code: 5.8;

[0085] After 10 weeks, the iron-cobalt color code will be 6.9.

[0086] After 16 weeks, the iron-cobalt color code is displayed as 7.8.

[0087] The iron-cobalt color code will be displayed after 24 weeks: 9.0.

[0088] Comparative Example 2

[0089] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0090] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide at room temperature for later use; weigh 1.6g (8‰) of the main antioxidant β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate n-octadecyl alcohol ester for later use.

[0091] (2) At room temperature, the weighed main antioxidant is slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide for 2 minutes; the mixture is stirred for 10 minutes at a stirring speed of 4000 r / min to form the product.

[0092] In this comparative example, only the main antioxidant was added. At room temperature, the mixed product obtained in step (2) was tested for color using an iron-cobalt colorimeter at the initial stage, 10 weeks, 16 weeks, and 24 weeks. The iron-cobalt colorimeter showed the following values:

[0093] Initial display of iron-cobalt color code: 5.8;

[0094] After 10 weeks, the iron-cobalt color code will be 6.3.

[0095] After 16 weeks, the iron-cobalt color code is displayed as 7.1.

[0096] The iron-cobalt color code will be displayed after 24 weeks: 7.8.

[0097] Comparative Example 3

[0098] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0099] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide at room temperature for later use; weigh 1.6g (8‰) of the auxiliary antioxidant di(octadecyl)thiodipropionate for later use;

[0100] (2) At room temperature, the auxiliary antioxidant weighed in step (1) is slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide for 2 minutes; and stirred for 10 minutes at a stirring speed of 4000 r / min to form the product.

[0101] In this comparative example, only an auxiliary antioxidant was added. At room temperature, the mixed product obtained in step (2) was tested for color using an iron-cobalt colorimeter at the initial stage, 10 weeks, 16 weeks, and 24 weeks. The iron-cobalt colorimeter showed the following values:

[0102] Initial display of iron-cobalt color code: 5.8;

[0103] After 10 weeks, the iron-cobalt color code will be 6.7.

[0104] After 16 weeks, the iron-cobalt color code is displayed as 7.5.

[0105] The iron-cobalt color code 8.4 will be displayed after 24 weeks.

[0106] As can be seen from Examples 1-6 and Comparative Examples 1-3, the addition of a composite antioxidant significantly controlled the color of the sulfur-containing silane coupling agent bis-[3-(triethoxysilane)propyl]-tetrasulfide during storage, effectively extending the shelf life of the sulfur-containing silane coupling agent Si69. To further verify the effectiveness of the added antioxidant, Experiment 1 was conducted under more stringent storage conditions. Furthermore, as can be seen from Comparative Examples 1 and 3, the addition of only an auxiliary antioxidant had virtually no significant effect on color control; synergistic action with the main antioxidant was required to achieve the desired effect of this invention.

[0107] Comparative Example 4

[0108] A method for controlling the color of sulfur-containing silane coupling agents is described in Example 6, except that different proportions of antioxidants are added, comprising the following steps:

[0109] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide solution at room temperature for later use; weigh 0.6g (3‰) of the main antioxidant N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine for later use; weigh 0.18g (0.9‰) of the auxiliary antioxidant di(octadecyl)thiodipropionate for later use;

[0110] (2) Same as step (2) in Example 6. After initial placement, 10 weeks, 16 weeks, and 24 weeks, the color was tested using an iron-cobalt color meter, and the iron-cobalt color code was displayed as follows:

[0111] Initial display of iron-cobalt color code: 5.8;

[0112] After 10 weeks, the iron-cobalt color code will be 6.5.

[0113] After 16 weeks, the iron-cobalt color code is displayed as 7.4.

[0114] The iron-cobalt color code will be displayed after 24 weeks: 7.8.

[0115] The comparison of their indicator data is shown in Table 1 below:

[0116] Table 1 Comparison of Indicator Data

[0117] Appearance light yellow Light yellow color with slight sediment. <![CDATA[Density / g / cm 3 > 1.085 1.086 Total sulfur content / % 22.4 22.7 γ2 content / % 0.8 0.9 Ethanol content / % 0.0 0.5 Other impurities content / % 0.09 0.92 Heating reduction 1.34 3.23

[0118] Comparative Example 5

[0119] A method for controlling the color of sulfur-containing silane coupling agents includes the following steps:

[0120] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide solution at room temperature for later use; weigh 4.0g (20‰) of the main antioxidant N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine and weigh 1.2g (6‰) of the auxiliary antioxidant di(octadecyl)thiodipropionate for later use;

[0121] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0122] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0123] Initial display of iron-cobalt color code: 5.8;

[0124] After 10 weeks, the iron-cobalt color code will be displayed as 6.1.

[0125] After 16 weeks, the iron-cobalt color code is displayed as 6.7.

[0126] The iron-cobalt color code will be displayed after 24 weeks: 7.7.

[0127] As can be seen from Examples 6 and Comparative Examples 4-5, the amount of composite antioxidant added has a certain impact on the color of the sulfur-containing silane coupling agent bis-[3-(triethoxysilane)propyl]-tetrasulfide during storage. Too little addition has a poor effect on color control, while too much addition does not significantly improve the color control effect. Instead, it affects the product indicators of the sulfur-containing silane coupling agent Si69, such as the loss on heating and the increase of impurities.

[0128] Comparative Example 6

[0129] A method for controlling the color of sulfur-containing silane coupling agents is as described in Example 1, except that the main antioxidant is an amine antioxidant, and includes the following steps:

[0130] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide solution at room temperature for later use; weigh 1.2g (6‰) of diethylamine, the main antioxidant, and weigh 0.4g (2‰) of di(octadecyl)thiodipropionate, the auxiliary antioxidant, for later use.

[0131] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0132] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0133] Initial display of iron-cobalt color code: 5.8;

[0134] After 10 weeks, the iron-cobalt color code will be 6.7.

[0135] After 16 weeks, the iron-cobalt color code is displayed as 7.5.

[0136] The iron-cobalt color code 8.1 will be displayed after 24 weeks.

[0137] Comparative Example 7

[0138] A method for controlling the color of sulfur-containing silane coupling agents is as described in Example 1, except that the main antioxidant is an organometallic salt antioxidant, comprising the following steps:

[0139] (1) Weigh 200g of bis-[3-(triethoxysilyl)propyl]-tetrasulfide solution at room temperature for later use; weigh 1.2g (6‰) of zinc oxide, the main antioxidant, and weigh 0.4g (2‰) of di(octadecyl)thiodipropionate, the auxiliary antioxidant;

[0140] (2) At room temperature, the main antioxidant and auxiliary antioxidant weighed in step (1) are slowly and evenly added to bis-[3-(triethoxysilane)propyl]-tetrasulfide, with an addition time of 2 min for each. Stir for 10 min at a stirring speed of 4000 r / min to form the product.

[0141] At room temperature, the mixed product obtained in step (2) was placed for the initial, 10-week, 16-week, and 24-week periods, and the color was tested using an iron-cobalt color meter, showing the following iron-cobalt color numbers:

[0142] Initial display of iron-cobalt color code: 5.8;

[0143] After 10 weeks, the iron-cobalt color code will be 6.6.

[0144] After 16 weeks, the iron-cobalt color code is displayed as 7.5.

[0145] The iron-cobalt color code will be displayed after 24 weeks: 8.0.

[0146] As can be seen from Examples 1 and Comparative Examples 6-7, other types of antioxidants have poor color control effects on the sulfur-containing silane coupling agent bis-[3-(triethoxysilyl)propyl]-tetrasulfide. The best color control effect is achieved when the main antioxidant β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate and the auxiliary antioxidant di(octadecyl)thiodipropionate are mixed in a 3:1 ratio as a composite antioxidant.

[0147] Experimental Example 1

[0148] To further determine the effect of adding Tianji composite antioxidant on the application performance of sulfur-containing silane coupling agents, a comparative application was conducted using Si69 and without added Si69 in Example 1, including the following steps:

[0149] (1) By weight, the composite material contains the following components: 96.5 parts of oil-extended styrene-butadiene rubber (37.5% oil-extended), 30 parts of cis-butadiene rubber (CB24), 59.5 parts of silica, 5 parts of sulfur-containing silane coupling agent Si69, 2 parts of antioxidant 4020, 1 part of microcrystalline wax, 2.6 parts of accelerator DPG-80, 3.70 parts of ZnO-80, 2 parts of accelerator CZ, and 1.87 parts of sulfur. The specific operation process for preparing the composite material includes the following steps:

[0150] (2) First stage mixing: At an initial temperature of 80℃ and a rotation speed of 50rpm, oil-extended styrene-butadiene rubber and butadiene rubber (CB24) are put into the internal mixer. The top plug is lowered. After 60 seconds, the top plug is lifted for 10 seconds and accelerator DPG-80, ZnO-80, antioxidant 4020, microcrystalline wax, and 1 / 2 of the silica are added. The top plug is lowered. After 90 seconds, the top plug is lifted for 10 seconds and the remaining silica and sulfur-containing silane coupling agent are added. The top plug is lowered. After that, the top plug is lifted every 1 minute to clean. The mixing time is 7 minutes and the discharge temperature is 143℃. The first stage of masterbatch is discharged and the open mill is pressed into sheets for cooling.

[0151] (3) Two-stage mixing: The first stage masterbatch is put into the internal mixer for 5 minutes of two-stage mixing. The grinding wheel is lifted and cleaned every 1 minute. The discharge temperature is 145℃. The second stage masterbatch is discharged, pressed into sheets by the open mill, and then cooled.

[0152] (4) Three-stage mixing: Same as two-stage mixing

[0153] (5) Final mixing: Mix the three sections of masterbatch on a two-roll mill, add accelerator CZ and sulfur after 1 minute of rolling, cut the left and right blades twice each within 2 minutes, make a triangular wrap 4 times after the material is finished, roll it 6 times and then sheet it.

[0154] (6) Vulcanization: The vulcanization characteristics of the rubber compound were tested using a rotorless close-mold vulcanizing apparatus. The temperature was set at 160℃ and the vulcanization time was 40 minutes. The experimental results are shown in Table 2 below:

[0155] Table 2 Comparison of Application Performance Data

[0156] Scorching time 98 100 Mooney viscosity 105 100 MH-ML 99 100 t90-t10 94 100 Tb 95 100 Tb after aging 100 100 Eb 104 100 M300 96 100 Tensile volume 95 100 Anti-aging post-tension 100 100 Rolling resistance 96 100 The Payne effect 98 100 Aging resistance coefficient 107 100 DIN wear 98 100

[0157] As can be seen from the above, the addition of the composite antioxidant of the present invention will not affect the performance of Si69. The sulfur-containing silane coupling agent Si69 with added composite antioxidant has comparable application performance to normal Si69, such as vulcanization, scorching, Mooney, mechanical properties, DIN wear and DMA. Its aging resistance is enhanced, which improves the aging resistance of the filler to a certain extent.

[0158] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A method for controlling the color of a sulfur-containing silane coupling agent, comprising the following steps: Add a composite antioxidant to the sulfur-containing silane coupling agent and stir until homogeneous; the composite antioxidant consists of a primary antioxidant and an auxiliary antioxidant, and the mass of the composite antioxidant added is 5-20‰ of the mass of the sulfur-containing silane coupling agent; The sulfur-containing silane coupling agent is sulfur-containing silane coupling agent Si69; the mass ratio of the primary antioxidant to the secondary antioxidant in the composite antioxidant is 1~5:1; the primary antioxidant is a phenolic antioxidant, which is one or more of monophenolic antioxidants, bisphenolic antioxidants, and polyphenolic antioxidants; the secondary antioxidant is di(octadecyl)thiodipropionate or 3-(dodecylthio)propionate-2,2-bis[[3-(dodecylthio)-propionyloxy] One or more of the following: [methyl]-1,3-propanediol ester, di(tetrazol) thiodipropionate, dilauryl thiodipropionate, 4,4'-thiobis(6-tert-butyl-2-methylphenol), 4,4'-thiobis(6-tert-butyl-m-cresol), tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(octadecyl) pentaerythritol diphosphite, and bis(2,4-dicumylphenyl) pentaerythritol diphosphite.

2. The method for controlling the color of sulfur-containing silane coupling agents according to claim 1, characterized in that, The mass of the composite antioxidant added is 8-15‰ of the mass of the sulfur-containing silane coupling agent.

3. The method for controlling the color of sulfur-containing silane coupling agents according to claim 1, characterized in that, The monophenolic antioxidant is one or more of β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate, 2,6-di-tert-butyl-p-cresol, and propyl gallate.

4. The method for controlling the color of sulfur-containing silane coupling agents according to claim 1, characterized in that, The bisphenol antioxidant is one or both of 2,2'-methylenebis-(4-methyl-6-tert-butylphenol) and di(2-methyl-5-tert-butyl-4-hydroxyphenyl) sulfide.

5. The method for controlling the color of sulfur-containing silane coupling agents according to claim 1, characterized in that, The polyphenolic antioxidant is one or two of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine.

6. The method for controlling the color of sulfur-containing silane coupling agents according to claim 1, characterized in that, The stirring speed is 3000~5000 r / min, and the stirring time is 10~20 min.