Hydrophobic agent and method for preparing hydrophobic white carbon black at low temperature using the same

Abstract

The present invention relates to the technical field of nanomaterial preparation, and in particular to a hydrophobic agent and a method for preparing hydrophobic white carbon black at low temperature using the same. The method comprises the following steps: 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane are mixed, a Pt catalyst is added, the mixture is introduced into a microchannel reactor, a heating reaction is carried out, a reaction kettle is entered to continue the stirring reaction, and the reaction heat in the microchannel reactor is used to heat the reaction kettle and remove unreacted components; a hydrophobic agent is obtained by distillation, and the bottom of the kettle is recycled as a catalyst; under the protection of nitrogen or an inert gas, white carbon black and a hydrophobic agent are mixed, and the mixture is heated and stirred to obtain hydrophobic white carbon black. The hydrophobic agent of the present invention contains a silicon-nitrogen bond with good reactivity and a trimethylsiloxy group rich in lipophilicity. These silicon-nitrogen bonds can effectively react and graft with the surface of white carbon black to form a stable chemical bond.

Description

Technical Field

[0001] The invention relates to the technical field of nano material preparation, and in particular to a hydrophobic agent and a method for preparing hydrophobic white carbon black at low temperature by using the hydrophobic agent. Background Art

[0002] Fumed silica, as a high-performance inorganic material, is mainly produced by the hydrolysis and polycondensation reaction of silicon tetrachloride or methyltrichlorosilane in a high-temperature hydrogen-oxygen flame environment. During this preparation process, the surface of silicon particles and their internal aggregates often retain a large number of silanol functional groups due to the incompleteness of the polycondensation reaction. In contrast, precipitated silica is produced through the chemical reaction of sodium silicate and sulfuric acid, and then through a series of physical treatment steps such as washing, precipitation and drying. Although the preparation paths of the two are different, their surfaces are both rich in silanols, and this commonality gives silica hydrophilic and oleophobic properties.

[0003] However, it is this hydrophilic and oleophobic property that limits the wetting and dispersion ability of silica in organic media to a large extent, thus restricting the wide application of fumed silica in many fields, such as rubber, plastic, coatings and ink industries. In order to overcome this limitation, the current industry mainly uses silicone oil, silazane or chlorosilane to treat the surface of fumed silica. Although silicone oil treatment can cover the surface of silica through adsorption, the treatment effect is limited, and some free polysiloxanes still fail to effectively bind; and when using small molecular weight silazanes, chlorosilanes or cyclosiloxanes for treatment, although the hydrophobicity of silica can be improved to a certain extent, due to the small molecular weight of the hydrophobic agent, the number of organic molecules that can be grafted is limited, and usually requires a higher treatment temperature, which consumes a lot of energy.

[0004] In view of the continuous growth of the application demand of silica in various fields, the development of a fumed silica surface treatment technology, aimed at achieving the effective grafting of large molecular weight molecules on the silica surface, thereby significantly improving its hydrophobicity and optimizing its dispersion and wetting properties in organic polymers, has become a technical problem that needs to be solved urgently. This technological breakthrough is not only expected to broaden the application scope of silica, but also provide strong support for the technological progress and product upgrades of related industries. Summary of the invention

[0005] In view of the deficiencies of the prior art, an object of the present invention is to provide a hydrophobic agent that can effectively improve the hydrophobic properties of white carbon black.

[0006] The present invention also provides a method for preparing hydrophobic silica at low temperature by using the same, wherein a hydrophobic agent having both a silicon-nitrogen bond with good reactivity and a trimethylsilyl group rich in lipophilicity is used to react with the hydrophobic silica, so that the hydroxyl groups on the surface of the hydrophilic silica are treated more thoroughly, and grafting can be achieved to obtain hydrophobic silica with good stability and large molecular weight.

[0007] The hydrophobic agent of the present invention is prepared by reacting 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane, as shown in Formula I:

[0008]

[0009] Formula I.

[0010] The method for preparing hydrophobic silica at low temperature using a hydrophobic agent according to the present invention comprises the following steps:

[0011] (1) 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane are mixed uniformly, a Pt catalyst is added to obtain a reaction liquid, the reaction liquid is introduced into a microchannel reactor, heated for reaction, and then introduced into a reaction kettle for continued reaction by heat preservation and stirring. After the reaction is completed, unreacted components are removed;

[0012] (2) The hydrophobic agent is obtained by distillation, and the bottom of the kettle is recycled as a catalyst;

[0013] (3) Under the protection of nitrogen or inert gas, mix the silica and the hydrophobic agent evenly, heat to 100~150℃ and stir to obtain hydrophobic silica.

[0014] The reaction mechanism of the hydrophobic agent of the present invention is as follows Figure 1 As shown, the reaction mechanism of hydrophobic agent treatment of silica is as follows Figure 2 shown.

[0015] The mixing ratio of 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane in step (1) is (2.02-2.2):1.

[0016] The Pt catalyst in step (1) includes Karstedt catalyst, Speier catalyst, chloroplatinic acid or the bottoms in step (2), and the amount used is 2-20 ppm based on Pt.

[0017] The process of uniformly mixing the white carbon black and the hydrophobic agent in step (3) is carried out under the protection of nitrogen or inert gas.

[0018] The inert gas is argon or helium.

[0019] The amount of the hydrophobic agent used in step (3) is 3-15% of the mass of the white carbon black.

[0020] The white carbon black in step (3) is hydrophilic fumed white carbon black or hydrophilic precipitated white carbon black, and the surface area is 150-380m 2 / g.

[0021] The reaction temperature of the heating reaction in step (1) is controlled by the microchannel reactor at 100-150°C. The reaction time of the reaction liquid in the microchannel is 2-10 minutes. The reaction liquid then enters the reactor and continues to stir and keep warm for 1-2 hours. The reaction heat in the microchannel reactor is used to heat the reactor.

[0022] The heat transfer oil device of the microchannel reaction equipment described in step (1) is connected to the heating heat transfer oil pipeline of the reactor, and the reaction heat is used to maintain the temperature of the reactor to continue the reaction.

[0023] The stirring treatment in step (3) takes 2 to 6 hours.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) In the preparation process of the hydrophobic agent of the present invention, the raw materials used are all common raw materials on the market, and these raw materials have been industrialized, so they are easy to obtain and have low cost. The catalyst used not only has the characteristics of recycling, but also shows high safety in the entire reaction process. After distillation treatment, the hydrophobic agent does not contain catalyst components, so it will not cause any adverse effects on subsequent application links.

[0026] 2) The hydrosilylation reaction has a fast reaction speed and releases heat violently during the reaction. There are great safety risks in carrying out such reactions in a single reactor, and many products and by-products are obtained. The reaction is carried out in a microchannel reactor. Due to the limited amount of liquid stored in the microchannel reactor, it can effectively initiate the reaction at a higher temperature and accurately control the temperature. In this way, most of the reactions can be completed in the microchannel reactor, effectively preventing the concentrated release of heat during the reaction, thereby avoiding potential dangers. In addition, the heat released by the hydrosilylation reaction in the microchannel reactor can be used to heat the subsequent reactor to continue to promote the reaction until the reaction is complete. The combined use of the microchannel reactor and the reactor can ensure the completeness of the reaction while improving the reaction efficiency. Compared with the traditional dropwise reaction, this method not only significantly shortens the reaction time, but also has the advantages of green energy saving.

[0027] 3) The hydrophobic agent structure of the present invention has a silicon-nitrogen bond with good reactivity and a trimethylsiloxy group rich in lipophilicity. These silicon-nitrogen bonds can effectively react and graft with the surface of silica to form a stable chemical bond. At the same time, the presence of trimethylsiloxy groups gives the hydrophobic agent excellent hydrophobicity.

[0028] 4) The hydrophobic silica prepared by the present invention has significant application advantages. Since the hydrophobic agent is a small molecule substance, it has strong permeability and can achieve a thorough treatment of the hydroxyl groups on the surface of the silica. This treatment makes the surface structure of the hydrophobic silica show a molecular structure containing a large amount of silicon methyl groups with a certain degree of freedom, thereby making it have excellent compatibility with various organic polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the reaction mechanism diagram of the hydrophobic agent of the present invention;

[0030] Figure 2 The figure is a reaction mechanism diagram of treating white carbon black with a hydrophobic agent according to the present invention;

[0031] Figure 3 is the hydrogen nuclear magnetic resonance spectrum of Example 1;

[0032] Figure 4 is the hydrogen nuclear magnetic resonance spectrum of Example 2;

[0033] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of Example 3. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the embodiments.

[0035] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0036] Example 1

[0037] The low-temperature preparation method of hydrophobic silica comprises the following steps:

[0038] (1) 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane were mixed evenly at a molar ratio of 1:2.05, and 15 ppm of Karstedt catalyst (in terms of Pt) was added. The mixture entered a microchannel reactor. The microchannel was kept at a stable temperature of 100°C. The reaction liquid was retained in the microchannel for 10 minutes. The mixture entered a reactor. The reaction heat in the microchannel reactor was used to heat the reactor. The temperature in the reactor was controlled to be 100°C. After the reaction was completed for 1 hour, the unreacted components were removed.

[0039] (2) The hydrophobic agent is obtained by distillation, and the bottom of the kettle is obtained at the same time; the nuclear magnetic resonance hydrogen spectrum of the hydrophobic agent is as follows: Figure 3 As shown;

[0040] (3) Under nitrogen protection, the specific surface area of ​​180m 2 / g hydrophilic precipitated silica ① and a hydrophobic agent are evenly mixed, the amount of the hydrophobic agent is 3% of the mass of the hydrophilic silica, heated to 140°C with stirring, reacted for 3h, to obtain hydrophobic silica 1.

[0041] The hydrophobic agent H NMR spectrum data are as follows:

[0042] 1 H NMR (CDCl3, 400 MHz): δ 1.09 (d, J = 7.6 Hz, 1.62H), 0.48-0.34 (m, 6.02H), 0.17-0.00 (m, 54.00H).

[0043] Example 2

[0044] The low-temperature preparation method of hydrophobic silica comprises the following steps:

[0045] (1) 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane were mixed evenly at a molar ratio of 1:2.10, and 5 ppm (in terms of Pt) of Pt catalyst Speier catalyst was added. The mixture entered the microchannel reactor, and the microchannel was kept at a stable temperature of 110°C. The reaction liquid was retained in the microchannel for 6 minutes. The mixture entered the reactor, and the reaction heat in the microchannel reactor was used to heat the reactor. The temperature in the reactor was controlled to be 110°C. After the reaction was completed for 2 hours, the unreacted components were removed.

[0046] (2) The hydrophobic agent is obtained by distillation, and the bottom of the kettle is obtained at the same time; the nuclear magnetic resonance hydrogen spectrum of the hydrophobic agent is as follows: Figure 4 As shown;

[0047] (3) Under helium protection, a surface area of ​​200m 2 / g hydrophilic fumed silica ② and a hydrophobic agent are evenly mixed, the amount of the hydrophobic agent is 10% of the mass of the hydrophilic silica, heated to 100°C with stirring, and reacted for 4h to obtain hydrophobic silica 2.

[0048] The hydrophobic agent H NMR spectrum data are as follows:

[0049] 1 H NMR (CDCl3, 400 MHz): δ 1.09 (d, J = 7.6 Hz, 1.62H), 0.48-0.34 (m, 6.02H), 0.17-0.00 (m, 54.00H).

[0050] Example 3

[0051] The low-temperature preparation method of hydrophobic silica comprises the following steps:

[0052] (1) 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane were mixed uniformly at a molar ratio of 1:2.20, and the bottom of the autoclave in Example 1 was added, with 20 ppm of Pt, and the mixture was heated to 150°C for reaction, and then the mixture entered the microchannel reactor. The microchannel was kept at a stable temperature of 150°C, and the retention time of the reaction liquid in the microchannel was 2 minutes. The mixture entered the reactor, and the reaction heat in the microchannel reactor was used to heat the reactor. The temperature in the reactor was controlled to be 150°C. After the reaction was completed for 1.5 hours, the unreacted components were removed;

[0053] (2) The hydrophobic agent is obtained by distillation, and the bottom of the kettle is obtained at the same time; the nuclear magnetic resonance hydrogen spectrum of the hydrophobic agent is as follows: Figure 5 As shown;

[0054] (3) Under argon protection, the specific surface area of ​​380m 2 / g hydrophilic fumed silica ③ and a hydrophobic agent are evenly mixed, the amount of the hydrophobic agent is 15% of the mass of the hydrophilic silica, heated to 150°C with stirring, and reacted for 6h to obtain hydrophobic silica 3.

[0055] The hydrophobic agent H NMR spectrum data are as follows:

[0056] 1 H NMR (CDCl3, 400 MHz): δ 1.09 (d, J = 7.6 Hz, 1.62H), 0.48-0.34 (m, 6.02H), 0.17-0.00 (m, 54.00H).

[0057] pass Figures 3-5 The analysis results show that the three products are basically the same, and are the following formula I structure and its isomers:

[0058]

[0059] Formula I.

[0060] The treated and untreated silica in the above examples were used as raw materials to prepare rubber compounds. Information on other raw materials used is shown in Tables 1 and 2 below.

[0061] Table 1: Raw rubber raw material information table

[0062]

[0063] Table 2: Hydroxy silicone oil raw material information

[0064]

[0065] Formula process:

[0066] Comparative test of white carbon black ① and white carbon black 1:

[0067] White carbon black ① formula: 110-8s: 650g, 110-2s: 100g, 110-7sk: 30g, white carbon black ①: 350g, hydroxy silicone oil: 25g, zinc stearate: 1.3g.

[0068] White carbon black 1: 110-8s: 650g, 110-2s: 100g, 110-7sk: 30g, white carbon black 1: 350g, hydroxy silicone oil: 18g, zinc stearate: 1.3g.

[0069] Comparative test of white carbon black ② and white carbon black 2:

[0070] White carbon black ②: 110-8s: 650g, 110-2s: 100g, 110-7sk: 30g, white carbon black ②: 350g, hydroxy silicone oil: 36g, zinc stearate: 1.3g.

[0071] White carbon black 2: 110-8s: 650g, 110-2s: 100g, 110-7sk: 30g, white carbon black 2: 350g, hydroxy silicone oil: 28g, zinc stearate: 1.3g.

[0072] Comparative test of white carbon black ③ and white carbon black 3:

[0073] White carbon black ③: 110-8s: 650g, 110-2s: 100g, 110-7sk: 30g, white carbon black ③: 350g, hydroxy silicone oil: 45g, zinc stearate: 1.3g.

[0074] White carbon black 3: 110-8s: 650g, 110-2s: 100g, 110-7sk: 30g, white carbon black 3: 350g, hydroxy silicone oil: 36g, zinc stearate: 1.3g.

[0075] Rubber mixing process: Add all the raw rubber, 150g of white carbon black, hydroxy silicone oil and zinc stearate into a kneader and knead into a mass. Then add the remaining white carbon black in 5 times. After all the white carbon black is added, knead evenly and mix at 150℃ for 2h to obtain the mixed rubber.

[0076] The mixed rubber is vulcanized to prepare silicone rubber, and the vulcanization process is as follows:

[0077] Take 70g of the mixed rubber, add 1wt% of the premixed rubber of bis(2,5-dimethylhexane) and polydimethylsiloxane with a molecular weight of 600,000-700,000 in a mass ratio of 1:1, and vulcanize at 170℃×6.5min on a flat vulcanizer to obtain silicone rubber. The obtained silicone rubber was subjected to mechanical property tests, wherein: Structural condition: 7d plasticity value growth rate was tested by GBT12828-2006, determination of plasticity value and recovery value of raw rubber and unvulcanized mixed rubber, and parallel plate method; the tensile strength was tested by GB / T528-2009, determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber; the elongation at break was tested by GB / T528-2009, determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber; the tear strength was tested by GB / T529-2008, determination of tear strength of vulcanized rubber or thermoplastic rubber; the hardness was tested by GB / T6031-2017, determination of hardness of vulcanized rubber or thermoplastic rubber.

[0078] The results are shown in Table 3 below:

[0079] Table 3: Mechanical properties test of silicone rubber

[0080]

[0081] From the above comparison, it can be seen that the reactive hydrophobic silica prepared by the present invention as a part of the reinforcing agent shows advantages in mechanical properties and is generally superior to the silicone rubber prepared by the traditional process.

[0082] Structured Situation Assessment:

[0083] The mixed rubber was stored at room temperature, and samples were taken at the initial stage, 1d, 3d, and 7d after production to test the plasticity value. The results are shown in Table 4 below:

[0084] Table 4: Plasticity value test results

[0085]

[0086] Through the above comparison, the plasticity value of the rubber compound prepared by using the hydrophobic silica prepared by the present invention increases slowly and changes slightly, thereby it can be determined that the rubber compound has better anti-structural performance and shelf life.

[0087] The carbon content of treated and untreated white carbon black in the above embodiment was tested using the GB / T20020-2013 fumed silica test method. The results are shown in Table 5 below:

[0088] Table 5: Carbon content test results

[0089]

[0090] It can be seen from the above table that the surface modification effect of the hydrophobic silica prepared in the embodiment of the present invention is good, and the grafting rate of the hydrophobic agent is high.

[0091] Thickening effect evaluation: 10g of sample was dispersed in 100g of dimethyl silicone oil with a viscosity of 350mPa·s, stirred for 10min, and the fluidity was visually observed. The performance evaluation results are shown in Table 6 below:

[0092] Table 6: Performance evaluation results

[0093]

[0094] Through the above comparison, the hydrophobically modified silica of the present invention has good hydrophobicity, and the hydrophobic silica prepared by the present invention has good fluidity after being mixed with dimethyl silicone oil, indicating that the silica is well modified.

Claims

1. A hydrophobic agent, characterized in that It is prepared by the reaction of 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane, as shown in Formula I: Formula I.

2. A method for preparing hydrophobic silica at low temperature using the hydrophobic agent according to claim 1, characterized in that: The following steps are involved: (1) 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane are mixed uniformly, a Pt catalyst is added to obtain a reaction liquid, the reaction liquid is introduced into a microchannel reactor, heated for reaction, and then introduced into a reaction kettle for continued reaction by heat preservation and stirring. After the reaction is completed, unreacted components are removed; (2) The hydrophobic agent is obtained by distillation, and the bottom of the kettle is recycled as a catalyst; (3) Mix the silica and the hydrophobic agent evenly, heat to 100-150°C and stir to obtain hydrophobic silica.

3. The method for preparing hydrophobic silica at low temperature according to claim 2, characterized in that: The mixing ratio of 1,3-divinyl-1,1,3,3-tetramethyldisilazane and 1,1,1,3,5,5,5-heptamethyltrisiloxane in step (1) is (2.02-2.2):

1.

4. The method for preparing hydrophobic silica at low temperature according to claim 2, characterized in that: The Pt catalyst in step (1) includes Karstedt catalyst, Speier catalyst, chloroplatinic acid or the bottoms in step (2), and the amount used is 2-20 ppm based on Pt.

5. The method for preparing hydrophobic silica at low temperature according to claim 2, characterized in that: The process of uniformly mixing the white carbon black and the hydrophobic agent in step (3) is carried out under the protection of nitrogen or inert gas.

6. The method for preparing hydrophobic silica at low temperature according to claim 2, characterized in that: The amount of the hydrophobic agent in step (3) is 3-15% of the mass of the white carbon black.

7. The method for preparing hydrophobic silica at low temperature according to claim 2, characterized in that: The white carbon black in step (3) is hydrophilic fumed white carbon black or hydrophilic precipitated white carbon black, and the surface area is 150-380m 2 / g.

8. The method for preparing hydrophobic silica at low temperature according to claim 2, characterized in that: The reaction temperature of the heating reaction in step (1) is controlled by the microchannel reactor at 100-150°C. The reaction time of the reaction liquid in the microchannel is 2-10 minutes. The reaction liquid then enters the reactor and continues to stir and keep warm for 1-2 hours. The reaction heat in the microchannel reactor is used to heat the reactor.

9. The method for preparing hydrophobic silica at low temperature according to claim 2, characterized in that: The stirring treatment in step (3) takes 2 to 6 hours.

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