CN100491452C - Preparation method of clay and styrene-butadiene rubber nanocomposite material modified by silane coupling agent - Google Patents

Abstract

The invention discloses a making method of clay modified by silane coupling agent with butadiene styrene rubber nanometer composite material, wherein the silane coupling agent is gamma-aminotriethylene silane and di-(gamma-triethylene propyl) tetrasulfide, which comprises the following steps: making gamma-aminotriethylene silane modified clay liquid suspension under normal temperature; blending with butylbenzene rubber emulsion completely; flocculating; washing; drying; fusing; sulfurizing to obtain the product; adding di-(gamma-triethylene propyl) tetrasulfide to obtain the modified clay and butadiene styrene rubber nanometer composite material of gamma-aminotriethylene silane and di-(gamma-triethylene propyl) tetrasulfide.

Description

Preparation method of clay and styrene-butadiene rubber nanocomposite material modified by silane coupling agent

technical field

The invention relates to a method for preparing clay and styrene-butadiene rubber nanocomposite material, in particular to a method for preparing clay and styrene-butadiene rubber nanocomposite material through in-situ organic modification of inorganic clay by emulsion intercalation method.

Background technique

As a resource-rich mineral, clay is cheap, has good physical and mechanical properties and high chemical resistance, and has a natural nanostructure. When clay is used as a reinforcing agent to prepare clay-rubber composite materials, it is dispersed in the polymer matrix as nano-units, which can exert its nano-effect and meet the requirements of high reinforcement and low density at the same time, so it can be used as a nano-scale rubber Reinforcing agent.

The existing preparation methods of clay/rubber nanocomposites include monomer intercalation in-situ polymerization, melt intercalation, solution intercalation and emulsion intercalation. Among them, the emulsion intercalation method is to mix the water suspension of inorganic montmorillonite with rubber emulsion, then carry out flocculation, dehydration and drying, mixing, vulcanization, and finally obtain clay/rubber nano composite material. Most rubbers can be made into emulsions. Compared with other methods, the emulsion intercalation method has simple process, easy control, low cost, and the prepared nanocomposite material has excellent performance. The patented technology of "Preparation Method of Clay/Rubber Nanocomposite Material" (ZL98101496.8) proposed by the applicant uses emulsion intercalation method to prepare composite material.

At present, there are many methods to make clay intercalation or exfoliation in rubber to prepare clay/rubber nanocomposites. The most common method is to use an organic modifier to organically modify the inorganic clay so that it becomes an organic soil containing an organic modifier between layers to facilitate the intercalation of rubber macromolecules. There are many kinds of organic modifiers used for the organic modification of clay. The commonly used ones are: organic quaternary ammonium salts, alkyl amino acids, polymer monomers, etc., and occasionally coupling agents are used to improve the wettability of the clay surface. Silane coupling agent is a class of silanes containing two different chemical groups (organic functional groups and hydrolyzable groups) in the molecule. It is usually used as a vulcanization aid for rubber composite materials to participate in the vulcanization reaction of rubber.

The applicant disclosed a method for preparing clay/butadiene rubber nanocomposites by organically modified clay and styrene-butadiene rubber nanocomposite (application number: 200510084326.8). The method for styrene rubber nanocomposite material, this method comprises the steps, A: the aqueous solution of clay suspension and alkyl quaternary ammonium salt modifier is mixed at 70 ℃, the mass ratio of alkyl quaternary ammonium salt modifier and clay 0.1 to 0.5 to obtain an organically modified mixed solution; B: Add styrene-butadiene rubber emulsion to the organically modified mixed solution, stir and mix evenly; C: Add flocculant for flocculation; D: Dehydrate and dry the flocs , to obtain floc gel; E: add various additives to floc gel, mix and vulcanize to obtain organically modified clay/styrene butadiene rubber nanocomposite material. The organically modified 10 g clay/100 g styrene-butadiene rubber nanocomposite was prepared by using an organic modifier cetyltrimethylammonium bromide to clay at a mass ratio of 0.4. The 300% modulus stress of the composite material is 3.4MPa, the tensile strength is 20.2MPa, the elongation at break is 596%, and the tear strength is 25.1KN/m. In the clay/styrene-butadiene rubber nanocomposite material prepared by the method, the distance between some clay sheets has reached more than 4.0nm, indicating that rubber macromolecules have been successfully inserted between the clay sheets. However, in the obtained organically modified clay/styrene-butadiene rubber nanocomposite, there is a physical combination between the clay and the rubber matrix, and the interface strength depends on the degree of physical entanglement between the molecular chain of the alkyl quaternary ammonium salt used and the rubber macromolecule. When subjected to external force, the interface between clay and rubber in the composite material slips, the molecular chains of the modifier are disentangled, and the composite material exhibits a lower modulus stress; when the deformation reaches a certain level (such as above 450%), the modified The molecular chain of the agent is straightened, and the clay sheet and the rubber macromolecule are lapped together by the modifier molecule, and the ability to resist external force is improved, which is manifested as a high tensile strength. With the increase of clay loading, the elongation at break of clay/styrene butadiene rubber nanocomposites will decrease significantly; the deformation will not reach a large enough level, and the tensile strength of the composites will be very low at this time. In addition, the organic modification of clay needs to be carried out at a temperature of 70°C during the preparation process, which consumes a lot of heat energy.

Contents of the invention

The purpose of this invention is to provide a method for improving the interface strength and performance of clay and styrene-butadiene rubber nanocomposites, using silane coupling agent modified clay to prepare clay and styrene-butadiene rubber nanocomposites with excellent mechanical properties, the method is An improved method to the "preparation method of organically modified clay and styrene-butadiene rubber nanocomposite" (application number: 200510084326.8) proposed by the applicant.

The preparation method of the clay and styrene-butadiene rubber nanocomposite material modified by the silane coupling agent of the present invention uses the silane coupling agent to carry out organic modification to the clay, and its operation steps are as follows:

(1) Preparation of organoclay water suspension: at room temperature, first stir and mix γ-aminopropyltriethoxysilane and clay water suspension to obtain γ-aminopropyltriethoxysilane modified clay water Suspension, the mass ratio of γ-aminopropyltriethoxysilane to clay is 0.05-0.5;

(2) Flocculation: Add the styrene-butadiene rubber emulsion into the clay water suspension modified by γ-aminopropyltriethoxysilane and stir, the mass ratio of clay to styrene-butadiene rubber is 0.05-0.4, then add flocculant, The flocs are washed and dried to obtain floc gel;

(3) Mixing: adding other additives to the flocculation gel and mixing to obtain the mixed rubber;

(4) Vulcanization: Vulcanize the mixed rubber to obtain a nanocomposite material of clay and styrene-butadiene rubber modified by γ-aminopropyltriethoxysilane.

In the present invention, bis-(γ-triethoxysilylpropyl)tetrasulfide and other additives are added to the floc gel in the above (3) mixing, and the γ- Aminopropyltriethoxysilane and bis-(γ-triethoxysilylpropyl) tetrasulfide modified clay and styrene-butadiene rubber nanocomposites, bis-(γ-triethoxysilylpropyl) The mass ratio of tetrasulfide to clay is 0.06-0.4.

The clay used in the invention is sodium-based bentonite, the average particle size of the clay is ≤80 microns, the cation exchange capacity is ≥70.6mmol/100g, and the montmorillonite content in the clay is ≥78%.

The solid content of the aqueous clay suspension used in the present invention is 2±0.5wt%.

The flocculant used in the present invention is sulfuric acid solution or hydrochloric acid solution with a mass concentration of 1%.

The inventive flocs were dried at 50°C.

The method of the present invention can obtain the clay/styrene-butadiene rubber nanocomposite of gamma-aminopropyl triethoxysilane modification or gamma-aminopropyl triethoxysilane and two-(gamma-triethoxysilyl Propyl) tetrasulfide co-modified clay/styrene butadiene rubber nanocomposites. The clay/styrene-butadiene rubber nanocomposite modified by the silane coupling agent prepared by the present invention can be directly used in rubber compounding design and product production, and it can also be mixed with other fillers (such as: carbon black, etc.) to prepare multiple A filler-filled styrene-butadiene rubber nanocomposite.

The clay used in the method of the invention is sodium-based bentonite, which has a layered crystal layer overlapping structure, and can be separated and dispersed in the rubber at a nanometer size. Clay and water are mixed and stirred to obtain a clay water suspension. The clay water suspension must be allowed to stand for a period of time, so that some clay particles and impurities with a large specific gravity that are extremely difficult to disperse will settle down. The solid content of the clay water suspension will increase with the static As time increases and decreases, the clay suspension in water becomes finer. The standing time is generally more than 24 hours, and the solid content can also be 1.5% for as long as 30 days. The dispersion distance of clay flakes in water depends on the solid content of the clay aqueous suspension. If the solid content is too high, it is difficult for latex particles to penetrate and isolate the clay. Co-flocculation of nanocomposites occurs with difficulty. Therefore, the solid content of the clay aqueous suspension should be 2±0.5% (by mass).

The inventive method adopts silane coupling agent to carry out organic modification to clay, and used silane coupling agent is gamma-aminopropyltriethoxysilane and bis-(gamma-triethoxysilylpropyl)tetrasulfide .

The gamma-aminopropyltriethoxysilane that the inventive method adopts in the modification stage of clay water suspension is a water-soluble silane coupling agent, in order to make the clay sheet fully organically modified, but will not be removed from the water precipitation, the mass ratio of γ-aminopropyltriethoxysilane to clay should be 0.05-0.5. Due to the low solid content of clay in the clay aqueous suspension, under the action of water, the clay sheets will be peeled off from each other and become a randomly dispersed single sheet, so that the organic modifier molecules are adsorbed between the clay sheets to form possible. γ-Aminopropyltriethoxysilane contains amino and ethoxy groups in its structure, and it will be hydrolyzed into aminopropyl silicon triol when it meets water. After mixing with clay water suspension, amino hydrated cations can be adsorbed on negatively charged clay slices. Controlling the dosage of γ-aminopropyltriethoxysilane can keep the clay in the clay water suspension still in a suspended state. After adding the styrene-butadiene rubber emulsion, under strong stirring, the latex particles can be inserted between the clay sheets to isolate them, and the organic modifier enters the clay sheets to make the clay sheets change from inorganic to organic, thereby improving The compatibility between the clay sheet and the rubber macromolecules is improved, and the dispersion of the clay in the rubber matrix is finer.

The organic modifier used in the mixing stage of the method of the present invention is two-(γ-triethoxysilylpropyl) tetrasulfide, which can be hydrolyzed into two-(γ-silicon trihydroxypropyl) with moisture in the air. ) tetrasulfide, thus chemically bonding with the γ-aminopropyltriethoxysilane hydrolyzate adsorbed on the clay sheet, and at the same time, it can participate in the vulcanization reaction of the rubber matrix, thereby introducing rubber macromolecules into the clay lamellae and improve interfacial bonding between clay and rubber. If the amount of bis-(γ-triethoxysilylpropyl)tetrasulfide is too low, the purpose of organic modification cannot be achieved; The increase is limited. On the other hand, the excess modifier will act as a liquid plasticizer, which will reduce the mechanical properties of the composite material. Therefore, considering the cost and the liquid characteristics of bis-(γ-triethoxysilylpropyl) tetrasulfide and the overall performance of the resulting composite material, bis-(γ-triethoxysilylpropyl) tetrasulfide The mass ratio to clay should be 0.06-0.4.

The method of the present invention has no special requirement to the kind of styrene-butadiene rubber emulsion, it can be the emulsion before the coagulation of the rubber synthesis process, and it can also be a rubber re-emulsification product, but in order to ensure that the latex particles and the clay sheets can be fully isolated and interspersed in the aqueous solution, The latex solid content should not be too high. The solid content of the currently commercially available styrene-butadiene latex products is between 18.0% and 23.0%, which can fully meet the requirements of the method of the present invention for the solid content of the styrene-butadiene latex.

The flocculant used in the method of the present invention is a conventional acidic polymer demulsifier, such as dilute sulfuric acid solution with a mass concentration of 1%, dilute hydrochloric acid and the like. If the concentration of flocculant is too high, raw materials will be wasted, and if the concentration is too low, the flocculation efficiency will be low.

The drying temperature of the floc in the method of the present invention should be about 50°C. Too high temperature will cause oxidative degradation of styrene-butadiene rubber material, and too low temperature will lead to low drying efficiency. Vacuum drying or other drying methods may be used.

The method of the present invention selects silane coupling agent to carry out organic modification, and carries out organic modification when preparing clay water suspension or preparing clay water suspension and mixing, and fully utilizes the characteristics of styrene-butadiene rubber in the form of water emulsion and organic modification The agent has the characteristics of water solubility, while organically modifying the clay, it promotes the insertion of rubber latex particles into the clay sheets, so that a chemical interface bond is formed between the clay and styrene-butadiene rubber, thereby greatly improving the interface strength and mechanical properties of the composite material. performance. The step of specially preparing the organic modified clay in the in-situ intercalation polymerization method, the melt intercalation method and the solution intercalation method is omitted, and the process is simplified.

The performance tests of the composite materials prepared by the present invention are all carried out according to the corresponding national standards. From the X-ray diffraction results of the composite material, it can be seen that in the composite material prepared by the method of the present invention, the rubber macromolecules enter between the clay lamellar layers, the distance between the clay lamellar layers expands, and there is an obvious intercalation phenomenon. It can be seen from the transmission electron microscope photos and the environmental scanning electron microscope photos of the composite material that the composite material prepared by the method of the invention has clay sheets uniformly dispersed in nanometer scale, and the interface between the clay and the rubber matrix is well bonded. It can be seen from the test results of the mechanical properties and gas barrier properties of the composite materials that the modulus stress, tensile strength, tear strength and gas barrier properties of the composite materials have been significantly improved. Compared with "Preparation method of organically modified clay and styrene-butadiene rubber nanocomposite" (patent application number: 200510084326.8), organic modification is carried out under normal temperature conditions, and no heating process is required in the process of preparing clay water suspension. Can reduce energy consumption. In the prepared composite material, there is a chemical interface between the clay and the rubber matrix. While ensuring the high tensile strength of the composite material, the modulus, tear strength, and gas barrier properties of the composite material are greatly improved. . In the highly filled 30g clay/100g styrene-butadiene rubber nanocomposite material prepared by the method of the invention, the clay sheet is still uniformly dispersed at the nanometer level in the matrix, and the obtained composite material has good mechanical properties and excellent gas barrier performance.

Description of drawings

Fig. 1 is the X-ray diffraction curve of the clay and styrene-butadiene rubber nanocomposite material modified by the silane coupling agent of the present invention. Among the figure, curve (a) is the composite material prepared in Example 1; Curve (b) is the composite material prepared in Example 2; Curve (c) is the composite material prepared in Example 4; Curve (d) is the composite material prepared in Example 5 Composite material prepared; Curve (e) is the composite material prepared in Example 6; Curve (f) is the composite material prepared in Example 8.

Figure 2 is the X-ray diffraction curve of the clay/styrene butadiene rubber nanocomposite. Among the figure, curve (a) is the composite material prepared by comparative example 2; curve (b) is the composite material prepared by comparative example 3; curve (c) is the composite material prepared by comparative example 4; curve (d) is the composite material prepared by comparative example 5 Composite materials prepared.

Detailed ways

The clay used in the examples of the present invention is all commercially available natural sodium bentonite, with an average particle size of ≤80, a montmorillonite content of ≥78% in the clay, and a cation exchange capacity of 70.6 mmol/100 g. The γ-aminopropyltriethoxysilane (trade name KH550), bis-(γ-triethoxysilylpropyl) tetrasulfide (trade name Si69), styrene-butadiene rubber latex (model 1502) used , solid content of 20.31%) are commercially available. Table 1 lists the amounts (parts by mass) of styrene-butadiene rubber, modifiers and clay used in Examples 1 to 13 of the present invention and the solid content (mass %) of the clay aqueous suspension. Table 2 lists the properties of the styrene-butadiene rubber composite materials prepared in Examples 1-13 and Comparative Examples 1-5. The gas barrier properties of the clay/styrene-butadiene rubber nanocomposites prepared in Examples 3, 7, 9, 10 and Comparative Example 1 are listed in Table 3.

Example 1

Stir 500 g of natural sodium bentonite in 10 L of water, the stirring speed is 1600 rpm, and the time is 5 hours. After mixing evenly, let it stand for 84 hours to obtain a clay water suspension with a solid content of 1.89%; take the clay water suspension 529g and 0.5gKH550 were mixed, stirred at room temperature for 30 minutes, and the stirring speed was 600 rpm to obtain a clay/KH550 aqueous suspension; the clay/KH550 aqueous suspension was stirred and mixed with 493g styrene-butadiene rubber latex at room temperature for 10 minutes, and the stirring speed was 1600 rpm; then dropwise add dilute sulfuric acid with a mass concentration of 1% for flocculation, and the final dosage of dilute sulfuric acid is 100 ml. Rinse the flocs with clean water 10 times to make the flocs pH = 7, and dry them at 50°C for 16 hours to obtain an organically modified floc gel, including 100 parts of styrene-butadiene rubber, 10 parts of clay, and 0.5 parts of modifier KH550.

On the double-roller mill, 110.5 parts of the above-mentioned organically modified flocculated gel were masticated, and then various additives (5 parts of zinc oxide, 2 parts of stearic acid, 0.5 part of accelerator D, and 0.5 part of accelerator D 0.5 part, accelerator TT 0.2 part, anti-aging agent 4010NA 1 part, sulfur 2 parts) mixing to obtain rubber compound. Vulcanize according to positive curing time at 150°C to obtain γ-aminopropyltriethoxysilane-modified clay and styrene-butadiene rubber nanocomposite material. Tested according to national standards, the mechanical properties of composite materials are shown in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (a) in Fig. 1 . In the styrene-butadiene rubber matrix, the distance between some clay sheets reached 5.01nm, indicating that a large number of rubber macromolecules were inserted between the clay sheets, which enhanced the interfacial interaction.

Example 2

The difference from Example 1 is that the dosage of KH550 is 2g, the dosage of flocculant is 102ml, and the rest of the process conditions and operation steps are the same as in Example 1. In the prepared composite material, there are 100 parts of rubber, 10 parts of clay, and 2 parts of KH5502. The mechanical properties of the composite materials are listed in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (b) in Fig. 1 .

Example 3

The difference from Example 1 is that the dosage of KH550 is 3g, the dosage of flocculant is 104ml, and the rest of the process conditions and operation steps are the same as in Example 1. In the prepared composite material, there are 100 parts of rubber, 10 parts of clay, and 3 parts of KH550. The mechanical properties of the composite materials are listed in Table 2. The gas barrier properties of the composites are listed in Table 3.

Example 4

The difference from Example 1 is that the dosage of KH550 is 5g, the dosage of flocculant is 105ml, and the rest of the process conditions and operation steps are the same as in Example 1. 100 parts of rubber, 10 parts of clay, and 5 parts of KH550 in the prepared composite material. The mechanical properties of the composite materials are listed in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (c) in Fig. 1 .

Example 5

The difference from Example 1 is that modifier Si69 is added to the flocculated gel during the mixing stage, and the rest of the steps and operating conditions are the same as in Example 1. In the composite material, there are 100 parts of rubber, 10 parts of clay, 0.5 parts of KH550, and 2 parts of Si69.

110.5 parts of flocculated gel prepared in Example 1 (100 parts of styrene-butadiene rubber, 10 parts of clay, 0.5 part of modifier KH550) were masticated on a double-roller open mill, and 2 g of Si69 modifier was added, and then various Auxiliaries (5 parts of zinc oxide, 2 parts of stearic acid, 0.5 part of accelerator D, 0.5 part of accelerator DM, 0.2 part of accelerator TT, 1 part of anti-aging agent 4010NA, 2 parts of sulfur) were mixed to obtain a rubber compound. Vulcanize at 150°C according to the positive curing time to obtain γ-aminopropyl triethoxysilane and styrene-butadiene rubber and bis-(γ-triethoxysilylpropyl) tetrasulfide modified clay soil and butyl Styrene rubber nanocomposites. Tested according to national standards, the mechanical properties of composite materials are shown in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (d) in Fig. 1 .

Example 6

The difference from Example 5 is that the dosage of KH550 is 2g, the dosage of flocculant is 102ml, and the rest of the process conditions and operation steps are the same as in Example 5. In the prepared composite material, there are 100 parts of rubber, 10 parts of clay, 2 parts of KH550, and 2 parts of Si69. The mechanical properties of the composite materials are listed in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (e) in Fig. 1 .

Example 7

The difference from Example 5 is that the dosage of KH550 is 3g, the dosage of flocculant is 104ml, and the rest of the process conditions and operation steps are the same as in Example 5. In the prepared composite material, there are 100 parts of rubber, 10 parts of clay, 3 parts of KH550, and 2 parts of Si69. The mechanical properties of the composite materials are listed in Table 2. The gas barrier properties of the composites are listed in Table 3. From the transmission electron microscope photos of the composite material, it can be seen that in the styrene-butadiene rubber matrix, the thickness of the clay sheet is between 10nm and 20nm, and the dispersion is uniform and fine. From the environmental scanning electron microscope photos of the composite material, it can be seen that the clay flakes are uniformly dispersed in the rubber matrix, the particle size is small, and the interface is well bonded.

Example 8

The difference from Example 5 is that the dosage of KH550 is 5g, the dosage of flocculant is 105ml, and the rest of the process conditions and operation steps are the same as in Example 5. In the prepared composite material, there are 100 parts of rubber, 10 parts of clay, 5 parts of KH550, and 2 parts of Si69. The mechanical properties of the composite materials are listed in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (f) in Fig. 1 .

Example 9

What is different from Example 1 is that after standing for 25 hours, the solid content is 1299g of clay aqueous suspension of 2.31%, the consumption of KH550 is 9g, and the consumption of flocculant is 120ml. All the other process conditions and operating steps are the same as in Example 1. The prepared composite material consists of 100 parts of rubber, 30 parts of clay, and 9 parts of KH5509. The mechanical properties of the composite materials are listed in Table 2. The gas barrier properties of the composites are listed in Table 3.

Example 10

Different from Example 5, it is 1299g of clay water suspension with a solid content of 2.31% for 25 hours, the consumption of KH550 is 9g, and the consumption of flocculant is 120ml. All the other process conditions and operating steps are the same as in Example 5. In the prepared composite material, there are 100 parts of rubber, 30 parts of clay, 9 parts of KH550 and 2 parts of Si69. The mechanical properties of the composite materials are listed in Table 2. The gas barrier properties of the composites are listed in Table 3. From the transmission electron microscope photos of the composite material, it can be seen that when the amount of clay reaches 30phr, the dispersion of the clay sheet in the styrene-butadiene rubber matrix is relatively uniform, and the sheet size is between 20 and 40nm, indicating that the organic modification makes the clay and rubber The interfacial compatibility between them is improved, which reduces the self-aggregation of clay to a certain extent. It is worth mentioning that the gas permeability of the composite material is 2.93×10 ^-17 m ² s ^-1 Pa ^-1 , which is only 42.6% of that of pure rubber (6.88×10 ^-17 m ² s ^-1 Pa ^-1 ). . This solves the problem that the clay in the styrene-butadiene rubber with high clay filling and reinforcement is seriously aggregated in industrial production, resulting in a significant decline in mechanical properties and gas barrier properties.

Example 11

Different from Example 1, it is 1732g of clay water suspension with a solid content of 2.31% for 25 hours, the consumption of KH550 is 20g, and the consumption of flocculant is 130ml. All the other process conditions and operating steps are the same as in Example 1. In the prepared composite material, there are 100 parts of rubber, 40 parts of clay, and 20 parts of KH550. The mechanical properties of the composite materials are listed in Table 2.

Example 12

Different from Example 5, it is 216g of clay water suspension with a solid content of 2.31% for 25 hours, the consumption of KH550 is 1.5g, and the consumption of flocculant is 100ml. All the other process conditions and operating steps are the same as in Example 5. In the prepared composite material, there are 100 parts of rubber, 5 parts of clay, 1.5 parts of KH550, and 2 parts of Si69. The mechanical properties of the composite materials are listed in Table 2.

Example 13

Different from Example 5, it is 866g of clay water suspension with a solid content of 2.31% for 25 hours, the consumption of KH550 is 6g, and the consumption of flocculant is 124ml. All the other process conditions and operating steps are the same as in Example 5. 100 parts of rubber, 20 parts of clay, 6 parts of KH5506, and 2 parts of Si69 in the prepared composite material. The mechanical properties of the composite materials are listed in Table 2.

Comparative example 1

The prepared composite material does not contain clay and is pure styrene-butadiene rubber, and the various auxiliary agents added during mixing are the same as those in Example 1. Add various additives to 100g styrene-butadiene rubber on a double-roller mill (in order: 5 parts of zinc oxide, 2 parts of stearic acid, 0.5 part of accelerator D, 0.5 part of accelerator DM, 0.2 part of accelerator TT , 1 part of anti-aging agent 4010NA, 2 parts of sulfur) mixing to obtain rubber compound. Then vulcanize at 150°C according to the positive curing time to obtain styrene-butadiene rubber. Tested according to national standards, the mechanical properties of the material are shown in Table 2. The gas barrier properties of the materials are listed in Table 3.

Comparative example 2

The operation steps are the same as the "Preparation Method of Clay/Rubber Nanocomposite" (ZL 98101496.8). Stir 500 g of natural sodium bentonite in 10 L of water, the stirring speed is 1600 rpm, and the time is 5 hours. After mixing evenly, let it stand for 96 hours to obtain a clay water suspension with a solid content of 2.2%; the clay water suspension 455g and 493g styrene-butadiene rubber latex (model 1502, solid content is 20.31%) carry out stirring and mixing at normal temperature for 30 minutes, and stirring speed is 1600 rev/mins; Then drip the dilute hydrochloric acid of mass concentration 2% to carry out flocculation, dilute hydrochloric acid final consumption is 2L. The flocs were washed with water for 30 minutes to make the pH of the flocs = 7, and dried at 50° C. for 18 hours to obtain a floc gel, including 100 parts of styrene-butadiene rubber and 10 parts of clay. On the double-roller mill, 110 parts of the above-mentioned flocculated gel were masticated, and then various additives (5 parts of zinc oxide, 2 parts of stearic acid, 0.5 part of accelerator D, 0.5 part of accelerator DM, and 0.2 parts of anti-aging agent TT, 1 part of anti-aging agent 4010NA, 2 parts of sulfur) to obtain a rubber compound. Then vulcanize at 150°C according to the positive vulcanization time to obtain the clay and styrene-butadiene rubber nanocomposite material. Tested according to national standards, the mechanical properties of the composite material are shown in Table 2, and the X-ray diffraction curve results of the composite material are shown in the curve (a) in Figure 2. From the TEM photo of the composite material, in the styrene-butadiene rubber matrix, the thickness of the clay sheet is about 30nm, which is greater than the clay sheet thickness (≤20nm) in the composite material of the same clay filling number prepared in Example 7 ; From the environmental scanning electron microscope photos of the composite material, the clay is evenly dispersed in the rubber matrix, but the interface is poor and there are many holes, indicating that the interface between the clay and the rubber is not well bonded; the layer spacing between the clay sheets Only 1.35nm, which is smaller than the interlamellar spacing of clay in the composite materials prepared in Examples 1, 2, 4, 5, 6 and 8, macromolecules cannot be inserted between clay layers, and the interface between clay and rubber is poor. The mechanical properties of composite materials, such as: modulus, tensile strength, tear strength, etc. are poor.

Comparative example 3

Prepared according to "Preparation method of organically modified clay and styrene-butadiene rubber nanocomposite material" (patent application number: 200510084326.8). The clay and water suspension after being stirred for 5 hours were placed for 96 hours to obtain a clay water suspension with a solid content of 2.31%; 5 g of the modifier cetyltrimethylammonium bromide was dissolved in 100 ml of water to obtain a modified The aqueous solution of the agent; get the clay aqueous suspension 433g and modifying agent aqueous solution to mix, stir at 70 ℃ for 30 minutes, stirring speed is 600 rev/min, obtain clay/quaternary ammonium salt suspension; Clay/quaternary ammonium salt aqueous solution and 493g styrene-butadiene rubber latex (model 1502, solid content is 20.31%) carried out stirring and mixing at normal temperature for 10 minutes, and the stirring speed was 1600 rev/min; then drip the dilute sulfuric acid of mass concentration 1% to carry out flocculation, dilute sulfuric acid final consumption 104 milliliters, Obtain floc gel, wherein 100 parts of styrene-butadiene rubber, 10 parts of clay, 5 parts of modifier. The operating steps and process conditions of mixing and vulcanization are the same as in Example 1. The mechanical properties of the prepared composites are listed in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (b) in Fig. 2 . Although the interlayer spacing of clay sheets in the composite material is 4.01nm, and the tensile strength of the composite material reaches above 20MPa, the modulus stress and tear strength of the composite material are poor.

Comparative example 4

Prepared according to "Preparation method of organically modified clay and styrene-butadiene rubber nanocomposite material" (patent application number: 200510084326.8). The difference from Comparative Example 3 is that the modifier is octadecyl vinyl dimethyl ammonium chloride, the amount of modifier is 2.0 g, and the rest of the process conditions are the same as Comparative Example 3. The mechanical properties of the prepared composites are listed in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (c) in Fig. 2 . Although the interlayer spacing of clay sheets in the composite is 4.66nm and the tensile strength of the composite is 18.7MPa, the modulus and tear strength of the composite are poor.

Comparative example 5

Prepared according to "Preparation method of organically modified clay and styrene-butadiene rubber nanocomposite material" (patent application number: 200510084326.8). The difference from Comparative Example 3 is that the modifier is dihexadecyldimethyl ammonium dichloride, and the dosage is 3.3 g, and the rest of the process conditions are the same as Comparative Example 3. The mechanical properties of the prepared composites are listed in Table 2. The results of the X-ray diffraction curve of the composite material are shown in the curve (d) in Fig. 2 . From the transmission electron microscope photos of the composite material, it can be seen that in the styrene-butadiene rubber matrix, the thickness of the clay sheet is between 10nm and 20nm, and the dispersion is fine, and the distance between some clay sheets reaches 5.54nm, indicating that a large number of rubber macromolecules are inserted into the clay. Between the sheets, the interfacial interaction is enhanced. However, since the modifier only acts as a physical compatibilizer, the interface between the clay and the rubber matrix in the composite is still a physical combination. Therefore, although the tensile strength of the composite is high, the modulus of modulus and tear strength Still poor.

Table 1

Dosage of KH550 (number of servings) Si69 dosage (number of copies) Clay solid content (wt%) Amount of clay (number of parts) Rubber consumption (parts) Example 1 0.5 0 1.89 10 100 Example 2 2 0 1.89 10 100 Example 3 3 0 1.89 10 100 Example 4 5 0 1.89 10 100 Example 5 0.5 2 1.89 10 100 Example 6 2 2 1.89 10 100 Example 7 3 2 1.89 10 100 Example 8 5 2 1.89 10 100 Example 9 9 0 2.31 30 100 Example 10 9 2 2.31 30 100 Example 11 20 0 2.31 40 100

Example 12 1.5 2 2.31 5 100 Example 13 6 2 2.31 20 100

Table 2

Shore A Hardness 100% modulus stress, MPa 300% modulus stress, MPa Tensile strength, MPa Elongation at break, % Tear strength, KN/m Example 1 60 1.7 3.2 4.6 507 31 Example 2 60 1.7 3.3 7.6 634 28 Example 3 59 1.8 4.0 11.6 627 32 Example 4 58 1.7 3.8 14.3 619 27 Example 5 60 2.1 7.0 11.2 506 42 Example 6 59 2.2 8.4 13.4 462 38 Example 7 59 2.3 9.0 16.9 509 39 Example 8 57 1.9 8.4 17.2 503 39 Example 9 70 2.8 6.0 15.0 773 49 Example 10 70 5.2 13.1 19.0 482 54 Example 11 73 5.0 9.8 17.2 616 51 Example 12 55 1.7 6.1 13.8 483 26 Example 13 63 3.1 10.0 19.1 567 44 Comparative example 1 47 0.9 1.1 2.3 632 9 Comparative example 2 59 1.1 2.8 8.0 560 27 Comparative example 3 64 1.2 3.5 22.9 560 twenty four Comparative example 4 57 1.0 2.5 18.7 638 28 Comparative example 5 61 1.3 3.1 18.5 61 25

table 3

sample Comparative example 1 Example 3 Example 7 Example 9 Example 10 Gas barrier property (10^-17m²s^-1Pa^-1) 6.88 4.78 5.26 3.46 2.93

Claims (5)

1. The preparation method of the clay and styrene-butadiene rubber nanocomposite material modified by silane coupling agent, the organoclay aqueous suspension is mixed with styrene-butadiene latex, and then through flocculation, drying, mixing and vulcanization, clay and styrene-butadiene rubber are obtained The nanocomposite material is characterized in that: the clay is organically modified with a silane coupling agent, the clay is sodium bentonite, the average particle diameter of the clay is ≤80 microns, the cation exchange capacity is ≥70.6mmol/100g, and the montmorillonite content in the clay is ≥78%; the operation steps are as follows: (1) Preparation of organoclay water suspension: at room temperature, first stir and mix γ-aminopropyltriethoxysilane and clay water suspension to obtain γ-aminopropyltriethoxysilane modified clay water Suspension, the mass ratio of γ-aminopropyltriethoxysilane to clay is 0.05-0.5; (2) Flocculation: Add the styrene-butadiene rubber emulsion into the clay water suspension modified by γ-aminopropyltriethoxysilane and stir, the mass ratio of clay to styrene-butadiene rubber is 0.05-0.4, then add flocculant, The flocs are washed and dried to obtain floc gel; (3) Mixing: adding the auxiliary agent into the flocculation gel and mixing to obtain the mixed rubber; (4) Vulcanization: Vulcanize the mixed rubber to obtain a nanocomposite material of clay and styrene-butadiene rubber modified by γ-aminopropyltriethoxysilane. 2. The method according to claim 1, characterized in that: in the (3) mixing process, bis-(γ-triethoxysilylpropyl)tetrasulfide is added to the flocculation together with other additives In the rubber, the clay and styrene-butadiene rubber nanocomposite materials modified by (4) vulcanization to obtain γ-aminopropyltriethoxysilane and bis-(γ-triethoxysilylpropyl) tetrasulfide, The mass ratio of bis-(γ-triethoxysilylpropyl)tetrasulfide to clay is 0.06-0.4. 3. The method according to claim 1, characterized in that the solid content of the clay aqueous suspension is 2±0.5wt%. 4. The method according to claim 1, characterized in that the flocculant is sulfuric acid solution or hydrochloric acid solution with a mass concentration of 1%. 5. A method according to claim 1, characterized in that the flocs are dried at 50°C.

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