Hindered phenol graft modified expandable graphite as well as preparation method and application thereof

Abstract

The invention discloses hindered phenol graft modified expandable graphite as well as a preparation method and application thereof. According to the invention, the hindered phenol grafted and modified expandable graphite is introduced into a butyl rubber system as a modified filler, on one hand, additional addition of an antioxidant is avoided, and at the same time, a reversible hydrogen-bond interaction is formed between hindered phenol and a polar side group in a rubber matrix, so that the damping effect of rubber can be improved, and a wider damping temperature range can be obtained; on the other hand, hindered phenol is introduced to the expansible graphite, so that the compatibility of the expansible graphite and the butyl rubber is improved, agglomeration of the expansible graphite in the butyl rubber is avoided, the bonding strength between interfaces of the expansible graphite and the butyl rubber is also improved, and the mechanical property and the flame retardant property of the composite material are improved; # imgabs0 #

Description

Technical Field

[0001] The invention relates to hindered phenol grafted modified expandable graphite and a preparation method thereof, as well as application of the graphite in damping materials. Background Art

[0002] With the rapid development of the automobile industry, the vibration and noise problems caused by fast-moving vehicles are becoming more and more serious. On the one hand, such problems will affect the safety and reliability of vehicle-mounted equipment, and on the other hand, they will reduce the riding experience of passengers. There are currently two commonly used solutions to this problem. The first is active vibration reduction technology. This vibration reduction mode uses sensors and regulators to control vibration in a timely manner. This device is complex in design, with high production, repair and maintenance costs and high technical difficulty. The second is passive vibration reduction technology, which effectively reduces the harm caused by vibration through the properties of the material itself. Its main advantage is that it does not require complex structural design, and its production and maintenance are simple and convenient. The vibration of the vehicle body is reduced by deforming the material under the action of external stress. By designing and studying the material formula, it can not only effectively improve the damping and vibration reduction effect of the material, but also optimize the physical and mechanical properties of the material, and greatly improve its service life.

[0003] Butyl rubber is a copolymer of isobutylene and a small amount of isoprene. Its molecular chain structure contains a large number of side methyl groups. The steric hindrance effect of these side methyl groups makes the butyl rubber molecular chain segments have large elastic hysteresis, energy dissipation and damping effects when they move, and the macroscopic performance is high damping. However, after butyl rubber is made into a composite damping sheet, its high and low temperature resistance, mechanical properties and flame retardant properties still have certain defects, which makes it have certain limitations.

[0004] Expandable graphite is obtained by special "expanding" treatment of graphite. Its physical and chemical properties are better than those of graphite. Its bulk density is 0.002-0.004g / cm 3 , loose and porous. The expansion characteristics of expandable graphite are different from other expanders. When subjected to high temperatures above 200°C, expandable graphite begins to expand and reaches its maximum volume at 1100°C, with the final volume reaching 280 times the initial volume. The expanded graphite changes from its original flake shape to a worm-like shape with very low density, forming a very good thermal insulation layer. The expanded graphite flakes are the carbon source in the expansion system and the thermal insulation layer, which can effectively insulate, so they are widely used in polymer flame retardant systems. Like other fillers, there is a problem when expandable graphite is added to the polymer system as a filler. It has poor compatibility with polymers and is prone to agglomeration, which not only affects the damping performance of the material, but also affects its mechanical properties. Therefore, it needs to be modified to improve its compatibility with the polymer matrix.

[0005] Hindered phenols, as an organic polar small molecule, are often modified and added to the rubber system as a functional additive. Adding organic polar small molecules such as hindered phenols to the polymer matrix can form reversible hydrogen bonds with polar side groups in the rubber matrix. When subjected to external stress or vibration, the hydrogen bonds in the material are weakened or broken, and new hydrogen bonds are continuously formed. This process will consume a large amount of energy in the system, convert mechanical energy into internal energy, and improve the damping performance of the composite material. For example: In the patent document CN201810262515.7, expandable graphite is modified by N-isopropyl-N'-phenyl-p-phenylenediamine to obtain expandable graphite-based antioxidant rubber, and a flame retardant and anti-aging rubber composite material is obtained; in the patent document CN202210681532.0, the modified expandable graphite obtained by modifying expandable graphite with a silane coupling agent is added to chlorobutyl rubber to obtain a flame retardant and high-damping chlorobutyl rubber composite material.

[0006] The above patent documents all adopt various measures to modify expandable graphite to obtain modified expandable graphite, and then add it to the rubber matrix to improve the damping performance of the rubber. However, the above patent documents have limited improvements on the damping performance, mechanical properties and anti-aging performance of polymer materials. Therefore, the development of new modified expandable graphite is of great practical significance for obtaining vibration reduction and noise reduction damping materials with excellent comprehensive performance. Summary of the invention

[0007] In view of the defects of existing materials, the present invention provides a hindered phenol grafted modified expandable graphite and a preparation method thereof, as well as an application of the graphite in damping materials.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing hindered phenol grafted modified expandable graphite, comprising the following steps:

[0010] (1) dispersing expandable graphite (after drying pretreatment) in anhydrous toluene, adding a silane coupling agent, heating to 120-140° C. and reflux reaction for 24 h, filtering, washing (with anhydrous toluene and anhydrous ethanol), and drying (105° C., 12 h) to obtain functionalized expandable graphite;

[0011] The mass ratio of expandable graphite to silane coupling agent is 12-24:21.6-43.2;

[0012] The silane coupling agent is selected from (3-aminopropyl)triethoxysilane or (3-aminopropyl)trimethoxysilane, preferably (3-aminopropyl)trimethoxysilane;

[0013] (2) Under nitrogen protection, (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid represented by formula I is dissolved in chloroform, the temperature is raised to 50-70° C., thionyl chloride is added dropwise, and the reaction is stirred for 6 hours to obtain an acyl chloride represented by formula II;

[0014] The mass ratio of (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid to thionyl chloride is 2.5-5:2-4;

[0015] (3) dispersing the functionalized expandable graphite obtained in step (1) in anhydrous toluene, adding the acyl chloride and catalyst obtained in step (2), stirring at room temperature and nitrogen atmosphere for 20 to 24 hours, filtering, washing (with anhydrous toluene and anhydrous ethanol), and drying (105° C., 12 hours) to obtain the hindered phenol grafted modified expandable graphite shown in formula III;

[0016] The mass ratio of functionalized expandable graphite, acyl chloride and catalyst is 6-12:2.8-5.6:8-16;

[0017] The catalyst is selected from one or a mixture of triethylamine (TEA) and dimethylaminopyridine (DMAP), preferably triethylamine;

[0018]

[0019] The invention relates to hindered phenol grafted modified expandable graphite prepared by the preparation method.

[0020] The hindered phenol grafted modified expandable graphite of the present invention can be used in damping materials; therefore, the present invention also relates to a butyl rubber damping material, which is prepared from the following components in weight ratio:

[0021] 100 parts of butyl rubber, 20-40 parts of hindered phenol grafted modified expandable graphite, 250 parts of filler, 80-100 parts of flame retardant, 30-50 parts of synergistic flame retardant, 150-200 parts of polyisobutylene, 30 parts of reinforcing agent, 30 parts of tackifier, and 10 parts of carbon black;

[0022] in,

[0023] The butyl rubber is selected from one or more of Exxon268, Xinhui 532, and Yanshan IIR1751;

[0024] The filler is selected from one or more of mica powder, light calcium powder and talcum powder;

[0025] The flame retardant is selected from one or more of decabromodiphenylethane and chlorinated paraffin;

[0026] The synergistic flame retardant is selected from one or more of zinc borate and antimony trioxide;

[0027] Polyisobutylene is selected from one or more of PB 680, PB1300, and PB2400;

[0028] The reinforcing agent is selected from one or more of fumed silica and precipitated silica;

[0029] The tackifier is selected from one or more of petroleum resin, terpene resin, phenolic resin and epoxy resin;

[0030] The carbon black is selected from one or more of N330, N774 and N990.

[0031] The preparation method of the butyl rubber damping material of the present invention is as follows:

[0032] Put the butyl rubber into an internal mixer and mix it at 80-100° C. for 10 minutes; then add a tackifier, carbon black and a reinforcing agent and continue mixing for 20 minutes; then add hindered phenol grafted modified expandable graphite, a flame retardant, a synergistic flame retardant and 1 / 2 of the formula amount of polyisobutylene (liquid) and continue mixing for 20 minutes; finally add a filler and the remaining 1 / 2 of the formula amount of polyisobutylene (liquid) and continue mixing for 40 minutes; discharge the material, and naturally cool it to room temperature to obtain the butyl rubber damping material.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention introduces organic side chains into expandable graphite by using a silane coupling agent, thereby effectively improving the compatibility of expandable graphite and butyl rubber, thereby enhancing the interfacial bonding strength between the two and improving the mechanical properties of the composite material.

[0035] (2) The present invention introduces hindered phenol grafted modified expandable graphite into the composite material system, avoiding the additional addition of antioxidants and improving the anti-aging performance of the material. At the same time, hydrogen bonds can be formed between the hindered phenol and the polar side groups in the rubber matrix, thereby obtaining a wider damping temperature range and better damping effect.

[0036] (3) The preparation process of the present invention is economical and practical, the preparation process is simple, the cost is low, no special equipment and harsh conditions are required, it is easy to achieve large-scale production, and it has extremely strong practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 : Synthetic route of hindered phenol grafted modified expandable graphite.

[0038] Figure 2 : The loss factor curves of the embodiment and the comparative example vary with temperature. DETAILED DESCRIPTION

[0039] The present invention is further described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0040] The glass transition temperature and damping performance of rubber were tested using a DMA-242E dynamic thermomechanical analyzer produced by NETZSCH, Germany.

[0041] GB / T 528-2009 and GB / T 2790-1995 were used to test the mechanical properties of rubber.

[0042] GB / T 3512-2001 is used to test the anti-aging properties of rubber.

[0043] GB / T 10707-2008 is used to test the flame retardant grade and oxygen index of rubber.

[0044] Example 1

[0045] 1. Preparation of Hindered Phenol Grafted Modified Expandable Graphite:

[0046] (1) The expandable graphite was placed in a vacuum drying oven at 105°C for 6 hours to remove excess moisture. 12.0 g of expandable graphite was dispersed in 400 mL of anhydrous toluene, 21.6 g of silane coupling agent ((3-aminopropyl)trimethoxysilane, the same below) was added to the suspension, the mixture was refluxed at 120°C for 24 hours with stirring, the product was filtered, and then washed three times with anhydrous toluene and anhydrous ethanol, and placed in a vacuum oven at 105°C for 12 hours to obtain functionalized expandable graphite;

[0047] (2) Under nitrogen protection, 2.5 g of (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid was dissolved in 50 mL of chloroform. After the temperature was raised to 50° C., 2 g of dichlorothionyl was slowly added dropwise to the chloroform solution and the mixture was slowly stirred for 6 h to obtain an acyl chloride.

[0048] (3) 6 g of functionalized expandable graphite was dispersed in 200 mL of anhydrous toluene, 2.8 g of acyl chloride was added, and then 8 g of triethylamine was added dropwise, and the mixture was stirred at room temperature under a nitrogen atmosphere for 20 h. The product was filtered and washed three times with anhydrous toluene and anhydrous ethanol, and dried in a vacuum oven at 105 °C for 12 h to obtain hindered phenol grafted modified expandable graphite.

[0049] 2. Preparation of butyl rubber damping material:

[0050] 50g of butyl rubber, 10g of hindered phenol grafted modified expandable graphite, 125g of mica powder, 40g of decabromodiphenylethane, 15g of zinc borate, 75g of PB1300, 15g of terpene resin, 15g of fumed silica and 5g of N330 carbon black were put into an internal mixer and mixed at a temperature of 80°C for 90min to obtain a butyl damping rubber composite material.

[0051] Example 2

[0052] 1. Preparation of Hindered Phenol Grafted Modified Expandable Graphite:

[0053] (1) The difference from Example 1 is the amount of reactants and the reaction temperature. The expandable graphite is placed in a vacuum drying oven at 105°C and dried for 6 hours to remove excess moisture. 18.0 g of expandable graphite is dispersed in 400 mL of anhydrous toluene, 32.4 g of silane coupling agent is added to the suspension, the mixture is refluxed at 130°C with stirring for 24 hours, the product is filtered, and then washed three times with anhydrous toluene and anhydrous ethanol, and placed in a vacuum oven at 105°C and dried for 12 hours to obtain functionalized expandable graphite;

[0054] (2) The difference from Example 1 is the amount of reactants and the reaction temperature. Under nitrogen protection, 3.75 g of (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid was dissolved in 75 mL of chloroform. After the temperature was raised to 60° C., 3 g of thionyl chloride was slowly added dropwise to the chloroform solution and stirred slowly for 6 h to obtain an acid chloride.

[0055] (3) The difference from Example 1 is the amount of reactants and the reaction time. 9 g of functionalized expandable graphite was dispersed in 200 mL of anhydrous toluene, 4.2 g of acyl chloride was added, and then 12 g of triethylamine was added dropwise, and the mixture was stirred at room temperature under nitrogen atmosphere for 22 h. The product was filtered and washed three times with anhydrous toluene and anhydrous ethanol, and dried in a vacuum oven at 105° C. for 12 h to obtain hindered phenol grafted modified expandable graphite.

[0056] 2. Preparation of butyl rubber damping material:

[0057] The difference from Example 1 is the amount of hindered phenol grafted modified expandable graphite, decabromodiphenylethane, zinc borate and polyisobutylene and the mixing temperature. 50g butyl rubber, 15g hindered phenol grafted modified expandable graphite, 125g mica powder, 45g decabromodiphenylethane, 20g zinc borate, 87.5g PB1300, 15g terpene resin, 15g fumed silica and 5g N330 carbon black were put into an internal mixer and mixed at a temperature of 90°C for 90 minutes to obtain a butyl damping rubber composite material.

[0058] Example 3

[0059] 1. Preparation of Hindered Phenol Grafted Modified Expandable Graphite:

[0060] (1) The difference from Example 1 is the amount of reactants and the reaction temperature. The expandable graphite was placed in a vacuum drying oven at 105°C and dried for 6 hours to remove excess moisture. 24.0 g of expandable graphite was dispersed in 400 mL of anhydrous toluene, 43.2 g of silane coupling agent was added to the suspension, the mixture was refluxed at 140°C with stirring for 24 hours, the product was filtered, and then washed three times with anhydrous toluene and anhydrous ethanol, and placed in a vacuum oven at 105°C and dried for 12 hours to obtain functionalized expandable graphite;

[0061] (2) The difference from Example 1 is the amount of reactants and the reaction temperature. Under nitrogen protection, 5 g of (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid was dissolved in 100 mL of chloroform. After the temperature was raised to 70°C, 4 g of thionyl chloride was slowly added dropwise to the chloroform solution and stirred slowly for 6 h to obtain an acyl chloride.

[0062] (3) Disperse 12 g of functionalized expandable graphite in 200 mL of anhydrous toluene, add 5.6 g of acyl chloride, and then add 16 g of triethylamine dropwise, and stir the mixture at room temperature under a nitrogen atmosphere for 24 h. Filter the product and wash it three times with anhydrous toluene and anhydrous ethanol, and dry it in a vacuum oven at 105 °C for 12 h to obtain hindered phenol grafted modified expandable graphite.

[0063] 2. Preparation of butyl rubber damping material:

[0064] The difference of Example 1 is the amount of hindered phenol graft modified expandable graphite, decabromodiphenylethane, zinc borate and polyisobutylene and the mixing temperature. 50g butyl rubber, 20g hindered phenol graft modified expandable graphite, 125g mica powder, 50g decabromodiphenylethane, 25g zinc borate, 100g PB1300, 15g terpene resin, 15g fumed silica and 5g N330 carbon black were put into an internal mixer and mixed at a temperature of 100°C for 90min to obtain a butyl damping rubber composite material.

[0065] Comparative Example 1

[0066] 50g of butyl rubber, 10g of expandable graphite, 125g of mica powder, 40g of decabromodiphenylethane, 15g of zinc borate, 75g of PB1300, 15g of terpene resin, 15g of fumed silica and 5g of N330 carbon black were put into an internal mixer and mixed at a temperature of 80°C for 90min to obtain a comparative butyl damping rubber composite material.

[0067] Comparative Example 2

[0068] The difference from Comparative Example 1 is the amount of expandable graphite, decabromodiphenylethane, zinc borate and polyisobutylene and the mixing temperature. 50g butyl rubber, 15g expandable graphite, 125g mica powder, 45g decabromodiphenylethane, 20g zinc borate, 87.5g PB1300, 15g terpene resin, 15g fumed silica and 5g N330 carbon black were put into an internal mixer and mixed at a temperature of 90°C for 90 minutes to obtain a comparative butyl damping rubber composite material.

[0069] Comparative Example 3

[0070] The difference from Comparative Example 1 is the amount of expandable graphite, decabromodiphenylethane, zinc borate and polyisobutylene and the mixing temperature. 50g butyl rubber, 20g expandable graphite, 125g mica powder, 50g decabromodiphenylethane, 25g zinc borate, 100g PB1300, 15g terpene resin, 15g fumed silica and 5g N330 carbon black were put into an internal mixer and mixed at a temperature of 100°C for 90min to obtain a comparative butyl damping rubber composite material.

[0071] Table 1 Test data of rubber material damping, flame retardant grade and oxygen index

[0072]

[0073] Table 2 Mechanical properties test data of rubber materials

[0074]

[0075] It can be seen from the experimental examples and comparative data that, compared with unmodified expandable graphite, the expandable graphite modified by introducing hindered phenol grafting can effectively improve the flame retardant grade, effective damping temperature range, mechanical strength and mechanical strength of the butyl rubber composite material under the same conditions. This is because the compatibility of the expandable graphite modified by hindered phenol grafting with butyl rubber has been significantly improved, so that the interfacial bonding strength between the two is improved, and the mechanical properties of the composite material are improved; the introduction of hindered phenol avoids the additional addition of antioxidants, improves the anti-aging performance of the material, and at the same time, the hindered phenol can form hydrogen bonds with the polar side groups in the rubber matrix, thereby obtaining a wider damping temperature range and better damping effect.

Claims

1. A method for preparing hindered phenol grafted modified expandable graphite, characterized in that: Here are the steps: (1) dispersing expandable graphite in anhydrous toluene, adding a silane coupling agent, heating to 120-140° C. for reflux reaction for 24 hours, filtering, washing, and drying to obtain functionalized expandable graphite; The silane coupling agent is selected from (3-aminopropyl)triethoxysilane or (3-aminopropyl)trimethoxysilane; (2) Under nitrogen protection, (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid represented by formula I is dissolved in chloroform, the temperature is raised to 50-70° C., thionyl chloride is added dropwise, and the reaction is stirred for 6 hours to obtain an acyl chloride represented by formula II; (3) dispersing the functionalized expandable graphite obtained in step (1) in anhydrous toluene, adding the acyl chloride and catalyst obtained in step (2), stirring for 20 to 24 hours at room temperature and nitrogen atmosphere, filtering, washing, and drying to obtain the hindered phenol grafted modified expandable graphite shown in formula III; The catalyst is selected from one or a mixture of triethylamine and dimethylaminopyridine; 2. The method for preparing the hindered phenol graft modified expandable graphite according to claim 1, characterized in that: In step (1), the mass ratio of expandable graphite to silane coupling agent is 12 to 24: 21.6～43.2。 3. The method for preparing the hindered phenol grafted modified expandable graphite according to claim 1, characterized in that: In step (2), the mass ratio of (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylic acid to dithionyl chloride is 2.5-5:2-4.

4. The method for preparing the hindered phenol grafted modified expandable graphite according to claim 1, characterized in that: In step (3), the mass ratio of the functionalized expandable graphite, the acyl chloride and the catalyst is 6-12:2.8-5.6:8-16.

5. Hindered phenol grafted modified expandable graphite obtained by the preparation method according to any one of claims 1 to 4.

6. Use of the hindered phenol grafted modified expandable graphite as claimed in claim 5 in damping materials.

7. A butyl rubber damping material, characterized in that: Made from the following ingredients in weight ratio: 100 parts of butyl rubber, 20-40 parts of the hindered phenol grafted modified expandable graphite according to claim 5, 250 parts of filler, 80-100 parts of flame retardant, 30-50 parts of synergistic flame retardant, 150-200 parts of polyisobutylene, 30 parts of reinforcing agent, 30 parts of tackifier, and 10 parts of carbon black; in, The butyl rubber is selected from one or more of Exxon268, Xinhui 532, and Yanshan IIR1751; The filler is selected from one or more of mica powder, light calcium powder and talcum powder; The flame retardant is selected from one or more of decabromodiphenylethane and chlorinated paraffin; The synergistic flame retardant is selected from one or more of zinc borate and antimony trioxide; Polyisobutylene is selected from one or more of PB 680, PB1300, and PB2400; The reinforcing agent is selected from one or more of fumed silica and precipitated silica; The tackifier is selected from one or more of petroleum resin, terpene resin, phenolic resin and epoxy resin; The carbon black is selected from one or more of N330, N774 and N990.

8. The method for preparing a butyl rubber damping material according to claim 7, characterized in that: The preparation method is as follows: Put the butyl rubber into an internal mixer and mix it at 80-100° C. for 10 minutes; then add a tackifier, carbon black and a reinforcing agent and continue mixing for 20 minutes; then add hindered phenol grafted modified expandable graphite, a flame retardant, a synergistic flame retardant and 1 / 2 of the formula amount of polyisobutylene and continue mixing for 20 minutes; finally add a filler and the remaining 1 / 2 of the formula amount of polyisobutylene and continue mixing for 40 minutes; discharge the material, and naturally cool it to room temperature to obtain the butyl rubber damping material.

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