Preparation method and application of a modified rutile-type nano titanium dioxide

Abstract

The present invention belongs to the technical field of titanium dioxide composite materials, and discloses a preparation method and application of modified rutile-type nano-titanium dioxide. In the present invention, water and n-hexanol are used as the microemulsion system, titanium tetrachloride is used as the titanium source, and sodium dodecyl sulfate is used as the surfactant. Through hydrothermal reaction, rutile-type nano-titanium dioxide with good dispersion and small particle size is obtained. Then, it is surface-modified with toluene-2,4-diisocyanate to obtain modified rutile-type nano-titanium dioxide. Using it as a filler, it is melt-blended with a copolymer of styrene and acrylate dimethylsilane monomers to obtain a polystyrene material. The isocyanate groups contained on the surface of the modified rutile-type nano-titanium dioxide can react with the hydroxyl groups of the polystyrene copolymer, significantly improving the mechanical properties, high-temperature resistance and anti-ultraviolet aging properties of the material.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium dioxide composite materials, and particularly relates to a preparation method and application of modified rutile-type nano-titanium dioxide. Background Art

[0002] Rutile-type nano-titanium dioxide has good ultraviolet absorption performance, a large specific surface area, and high mechanical strength. It is widely used in polymer materials such as polystyrene, polyethylene, and polyurethane, and can be used as a toughening agent, anti-ultraviolet absorber to improve the mechanical properties and anti-ultraviolet aging properties of materials. However, rutile-type nano-titanium dioxide is prone to agglomeration, and its compatibility with the polymer material matrix is poor, resulting in poor enhancement effect. Improving the compatibility and interfacial properties between the material and nano-titanium dioxide is a research hotspot.

[0003] Polystyrene is a common polymer material with a simple preparation method and low cost. It can be made into products such as foams, plastics, films, and fibers, and has a wide range of applications in packaging, containers, thermal insulation materials, optical components, etc. The patent with publication number CN118256042A discloses using rutile titanium dioxide loaded with antimony tin oxide as a coating, which endows the polystyrene foaming material with antistatic and flame retardant properties. However, this patent does not improve the high-temperature resistance and mechanical strength of the polystyrene material. Summary of the Invention

[0004] The technical problem solved by the present invention is: to provide a preparation method and application of modified rutile-type nano-titanium dioxide, which solves the problems of poor dispersibility of rutile-type nano-titanium dioxide and poor compatibility with polystyrene materials.

[0005] The technical solution of the present invention is: a preparation method of modified rutile-type nano-titanium dioxide, comprising the following steps:

[0006] Step (1): Add water and titanium tetrachloride to a reaction vessel under ice bath. After stirring, add n-hexanol and sodium dodecyl sulfate, stir and mix evenly, pour the solution into a reaction kettle, filter after reaction, wash successively with water and ethanol, and dry to obtain rutile-type nano-titanium dioxide.

[0007] Step (2): Add toluene and rutile-type nano-titanium dioxide to a reaction vessel, disperse by ultrasonic, then add toluene-2,4-diisocyanate, heat to 100 - 110 °C, react for 2 - 3 h, filter, wash with toluene, and dry to obtain modified rutile-type nano-titanium dioxide.

[0008] Preferably, the ratio of water, titanium tetrachloride, n-hexanol, and sodium dodecyl sulfate in step (1) is 1 L : (120 - 200) g : (6 - 7) L : (80 - 130) g.

[0009] Preferably, in step (1), the reaction temperature is 80 - 100 °C and the time is 12 - 18 h.

[0010] Preferably, in step (2), the ratio of rutile-type nano titanium dioxide to toluene-2,4-diisocyanate is 1 g : (0.4 - 1) g.

[0011] Preferably, it is the application of modified rutile-type nano titanium dioxide in high-temperature resistant and anti-aging polystyrene.

[0012] Preferably, the preparation method of the high-temperature resistant and anti-aging polystyrene comprises the following steps:

[0013] Step A: Add tetrahydrofuran, bis(4-aminophenoxy)dimethylsilane with a ratio of 1 g : (1.03 - 1.1) g, and glycidyl methacrylate into the reaction vessel, heat to 40 - 50 °C, stir and react for 3 - 5 h, carry out vacuum distillation, wash successively with petroleum ether and acetone, and dry to obtain acrylate dimethylsilane monomer. The preparation reaction formula is:

[0014]

[0015] Step B: Add toluene, styrene, and acrylate dimethylsilane monomer into the reaction vessel, introduce nitrogen, add azobisisobutyronitrile, heat to 70 - 85 °C, react for 7 - 10 h, carry out vacuum distillation, wash with ethanol, and dry to obtain a polystyrene copolymer.

[0016] Step C: Add the polystyrene copolymer, modified rutile-type nano titanium dioxide, and antioxidant into a twin-screw extruder, keep the temperature of the 1st - 5th sections at 190 - 220 °C, carry out melt blending, extrusion, and pelletizing to obtain high-temperature resistant and anti-aging polystyrene.

[0017] Preferably, in step B, the mass ratio of styrene to acrylate dimethylsilane monomer is 1 g : (0.1 - 0.3) g.

[0018] Preferably, in step C, the mass ratio of the polystyrene copolymer to modified rutile-type nano titanium dioxide is 100 g : (0.5 - 4) g.

[0019] Technical effect: In the present invention, water and n-hexanol are used as the microemulsion system, titanium tetrachloride is used as the titanium source, and sodium dodecyl sulfate is used as the surfactant. Through a hydrothermal reaction, rutile-type nano titanium dioxide with good dispersibility and small particle size is obtained; then it is surface-modified with toluene-2,4-diisocyanate to obtain modified rutile-type nano titanium dioxide with isocyanate groups on the surface.

[0020] In the present invention, bis(4-aminophenoxy)dimethylsilane and glycidyl methacrylate are subjected to a ring-opening reaction to obtain an acrylate dimethylsilane monomer, which is then copolymerized with a styrene monomer to obtain a polystyrene copolymer. Finally, modified rutile-type nano titanium dioxide is used as a filler for melt blending to obtain a high-temperature resistant and anti-aging polystyrene.

[0021] After the rutile-type nano titanium dioxide of the present invention is modified with toluene diisocyanate, its dispersibility is better, and its compatibility with the polystyrene copolymer matrix is excellent, which is beneficial to improving the tensile properties of polystyrene. At the same time, the isocyanate groups contained on the surface of the modified rutile-type nano titanium dioxide can react with the hydroxyl groups of the polystyrene copolymer during high-temperature melt blending in a screw extruder, thereby grafting the nano titanium dioxide onto the polystyrene copolymer molecular chain, enhancing the bonding strength between the two, enabling the nano titanium dioxide to play a better reinforcing role, and further improving the tensile strength and elongation at break of polystyrene. And the rutile-type nano titanium dioxide has a strong ultraviolet absorption ability and is uniformly dispersed in the polystyrene matrix, significantly improving its anti-ultraviolet aging performance.

[0022] The molecular chain of the polystyrene copolymer of the present invention contains a diphenylsiloxane structure, has strong heat resistance and good thermal decomposition resistance, which is beneficial to improving the heat resistance of the material. And the isocyanate groups of the modified rutile-type nano titanium dioxide react with the hydroxyl groups of the polystyrene copolymer to form a chemical crosslinking effect between the nano titanium dioxide and the polystyrene, increasing the crosslinking degree of the polystyrene molecular chain, restricting the movement of the molecular chain, thereby increasing the thermal decomposition temperature of the polystyrene material, showing a higher initial thermal decomposition temperature and maximum thermal decomposition rate temperature, and significantly improving the high-temperature resistance of the material. Detailed Embodiments

[0023] In order to be able to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the examples, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein.

[0024] Example 1

[0025] Step (1): Add 100 mL of water and 20 g of titanium tetrachloride to a reaction vessel under an ice bath, stir and then add 700 mL of n-hexanol and 13 g of sodium dodecyl sulfate, stir and mix evenly, pour the solution into a reaction kettle, heat to 90 °C, react for 18 h, filter, wash successively with water and ethanol, and dry to obtain rutile-type nano titanium dioxide.

[0026] Step (2): Add 600 mL of toluene and 5 g of rutile-type nano-titanium dioxide into a reaction vessel equipped with a condensing reflux pipe, disperse by ultrasonic treatment, then add 4 g of toluene-2,4-diisocyanate, heat to 110 °C, react for 2 h, filter, wash with toluene, and dry to obtain modified rutile-type nano-titanium dioxide.

[0027] Example 2

[0028] Step (1): Add 100 mL of water and 12 g of titanium tetrachloride into a reaction vessel under ice bath, stir and then add 600 mL of n-hexanol and 8 g of sodium dodecyl sulfate, stir and mix evenly, pour the solution into a reaction kettle, heat to 100 °C, react for 12 h, filter, wash successively with water and ethanol, and dry to obtain rutile-type nano-titanium dioxide.

[0029] Step (2): Add 600 mL of toluene and 5 g of rutile-type nano-titanium dioxide into a reaction vessel equipped with a condensing reflux pipe, disperse by ultrasonic treatment, then add 2 g of toluene-2,4-diisocyanate, heat to 100 °C, react for 3 h, filter, wash with toluene, and dry to obtain modified rutile-type nano-titanium dioxide.

[0030] Example 3

[0031] Step (1): Add 100 mL of water and 15 g of titanium tetrachloride into a reaction vessel under ice bath, stir and then add 650 mL of n-hexanol and 10 g of sodium dodecyl sulfate, stir and mix evenly, pour the solution into a reaction kettle, heat to 80 °C, react for 18 h, filter, wash successively with water and ethanol, and dry to obtain rutile-type nano-titanium dioxide.

[0032] Step (2): Add 800 mL of toluene and 5 g of rutile-type nano-titanium dioxide into a reaction vessel equipped with a condensing reflux pipe, disperse by ultrasonic treatment, then add 5 g of toluene-2,4-diisocyanate, heat to 110 °C, react for 2 h, filter, wash with toluene, and dry to obtain modified rutile-type nano-titanium dioxide.

[0033] Comparative Example 1

[0034] Step (1): Add 100 mL of water and 20 g of titanium tetrachloride into a reaction vessel under ice bath, stir and then add 700 mL of n-hexanol, stir and mix evenly, pour the solution into a reaction kettle, heat to 90 °C, react for 18 h, filter, wash successively with water and ethanol, and dry to obtain rutile-type nano-titanium dioxide.

[0035] Step (2): Add 600 mL of toluene and 5 g of rutile-type nano-titanium dioxide into a reaction vessel equipped with a condensing reflux pipe. Disperse them by ultrasonic treatment, then add 4 g of toluene-2,4-diisocyanate, heat to 110 °C, react for 2 h, filter, wash with toluene, and dry to obtain modified rutile-type nano-titanium dioxide.

[0036] The rutile-type nano-titanium dioxide was characterized by XRD using an X-ray diffractometer. The average grain size D of the nano-titanium dioxide grains was measured by the X-ray broadening method.

[0037] D = K×λ / (β×cosθ). K is a constant of 0.89; λ is the X-ray wavelength; θ is the half diffraction angle; β is the full width at half maximum of the strongest diffraction peak in the XRD pattern. The test results are shown in Table 1.

[0038] Table 1 Average grain size of nano-titanium dioxide

[0039]

[0040] Example 4

[0041] (1) Add 300 mL of tetrahydrofuran, 20 g of bis(4-aminophenoxy)dimethylsilane, and 22 g of glycidyl methacrylate into a reaction vessel, heat to 40 °C, stir and react for 5 h, carry out vacuum distillation, wash successively with petroleum ether and acetone, and dry to obtain acrylate dimethylsilane monomer.

[0042] (2) Add 800 mL of toluene, 100 g of styrene, and 10 g of acrylate dimethylsilane monomer into a reaction vessel, introduce nitrogen, add 0.5 g of azobisisobutyronitrile, heat to 85 °C, react for 7 h, carry out vacuum distillation, wash with ethanol, and dry to obtain polystyrene copolymer.

[0043] (3) Add 1 kg of polystyrene copolymer, 5 g of modified rutile-type nano-titanium dioxide (prepared by the method of Example 1), and 4 g of antioxidant 1010 into a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C respectively. Carry out melt blending, extrusion, and pelletizing to obtain high-temperature resistant and anti-aging polystyrene.

[0044] Example 5

[0045] (1) Add 250 mL of tetrahydrofuran, 20 g of bis(4-aminophenoxy)dimethylsilane, and 20.6 g of glycidyl methacrylate into a reaction vessel, heat to 40 °C, stir and react for 5 h, carry out vacuum distillation, wash successively with petroleum ether and acetone, and dry to obtain acrylate dimethylsilane monomer.

[0046] (2) Add 1000 mL of toluene, 100 g of styrene, and 20 g of acrylate dimethylsilane monomer to the reaction vessel. Introduce nitrogen gas, add 0.56 g of azobisisobutyronitrile, heat to 75 °C, react for 10 h, perform vacuum distillation, wash with ethanol, and dry to obtain a polystyrene copolymer.

[0047] (3) Add 1 kg of polystyrene copolymer, 5 g of modified rutile-type nano titanium dioxide (prepared according to the method of Example 1), and 4 g of antioxidant 1010 to a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C. Perform melt blending, extrusion, and pelletizing to obtain heat-resistant and anti-aging polystyrene.

[0048] Example 6

[0049] (1) Add 300 mL of tetrahydrofuran, 20 g of bis(4-aminophenoxy)dimethylsilane, and 20.6 g of glycidyl methacrylate to the reaction vessel. Heat to 50 °C and stir to react for 3 h. Perform vacuum distillation, wash successively with petroleum ether and acetone, and dry to obtain acrylate dimethylsilane monomer.

[0050] Step (2) Add 1000 mL of toluene, 100 g of styrene, and 30 g of acrylate dimethylsilane monomer to the reaction vessel. Introduce nitrogen gas, add 0.65 g of azobisisobutyronitrile, heat to 70 °C, react for 10 h, perform vacuum distillation, wash with ethanol, and dry to obtain a polystyrene copolymer.

[0051] Step (3) Add 1 kg of polystyrene copolymer, 5 g of modified rutile-type nano titanium dioxide (prepared according to the method of Example 1), and 4 g of antioxidant 1010 to a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C. Perform melt blending, extrusion, and pelletizing to obtain heat-resistant and anti-aging polystyrene.

[0052] Example 7

[0053] (1) Add 1 kg of polystyrene copolymer (prepared according to the method of Example 4), 20 g of modified rutile-type nano titanium dioxide (prepared according to the method of Example 1), and 4 g of antioxidant 1010 to a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C. Perform melt blending, extrusion, and pelletizing to obtain heat-resistant and anti-aging polystyrene.

[0054] Example 8

[0055] (1) Add 1 kg of polystyrene copolymer (prepared according to the method of Example 4), 40 g of modified rutile-type nano-titanium dioxide (prepared according to the method of Example 1), and 4 g of antioxidant 1010 into a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C. Melt and blend, extrude, and pelletize to obtain high-temperature resistant and anti-aging polystyrene.

[0056] Comparative Example 2

[0057] (1) Add 1 kg of polystyrene copolymer (prepared according to the method of Example 4) and 4 g of antioxidant 1010 into a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C. Melt and blend, extrude, and pelletize to obtain high-temperature resistant and anti-aging polystyrene.

[0058] Comparative Example 3

[0059] (1) Add 1 kg of polystyrene copolymer (prepared according to the method of Example 4), 5 g of rutile-type nano-titanium dioxide (prepared according to the method of Example 1), and 4 g of antioxidant 1010 into a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C. Melt and blend, extrude, and pelletize to obtain high-temperature resistant and anti-aging polystyrene.

[0060] Comparative Example 4

[0061] (1) Add 800 mL of toluene and 100 g of styrene into a reaction vessel. Pass in nitrogen, add 0.5 g of azobisisobutyronitrile, heat to 85 °C, react for 7 h, carry out vacuum distillation, wash with ethanol, and dry to obtain polystyrene.

[0062] (2) Add 1 kg of polystyrene, 5 g of modified rutile-type nano-titanium dioxide (prepared according to the method of Example 1), and 4 g of antioxidant 1010 into a twin-screw extruder. The temperatures of the 1st - 5th sections are 190 °C, 200 °C, 220 °C, 220 °C, and 215 °C. Melt and blend, extrude, and pelletize to obtain high-temperature resistant and anti-aging polystyrene.

[0063] Mold the polystyrene in a flat vulcanizing machine at a pressure of 10 MPa, a temperature of 210 °C, and a time of 15 min to form a sheet. The tensile properties are tested according to the GB / T 1040.1 - 2018 standard.

[0064] Place the polystyrene sheet in an ultraviolet lamp accelerated aging test chamber and carry out ultraviolet lamp accelerated aging for 240 h with a light intensity of 40 mW / cm 2 ; the relative humidity is 60%. Then test the tensile properties. The test results are shown in Table 2.

[0065] Table 2 Tensile Property Test of Polystyrene Sheets

[0066]

[0067]

[0068] As can be seen from the above table, compared with Comparative Example 2, modified rutile-type nano-titanium dioxide was added to the high-temperature resistant and anti-aging polystyrene in Examples 4-6, and the tensile strength and elongation at break were significantly improved, reaching 28.0-29.1 MPa and 54.2-54.8%.

[0069] Moreover, after ultraviolet light aging, the decline in tensile strength and elongation at break was very small. Taking Example 4 as an example, the retention rate of tensile strength before and after aging was 28.2÷29.1 = 96.91%, and the retention rate of elongation at break was 52.4÷54.2 = 96.68%. It has good anti-ultraviolet aging performance.

[0070] The retention rate of tensile strength before and after aging in Comparative Example 2 was 21.6÷24.1 = 89.63%, and the retention rate of elongation at break was 42.6÷48.6 = 87.65%. The retention rates of tensile strength and elongation at break were significantly lower than those in Example 4. This is mainly because modified rutile-type nano-titanium dioxide was added in Examples 4-6. After the rutile-type nano-titanium dioxide was modified with toluene diisocyanate, its dispersibility was better, and its compatibility with the polystyrene copolymer matrix was excellent, which was beneficial to improving the tensile properties of polystyrene. At the same time, the isocyanate groups contained on the surface of the modified rutile-type nano-titanium dioxide could react with the hydroxyl groups of the polystyrene copolymer during high-temperature melt blending in a screw extruder, thereby grafting the nano-titanium dioxide onto the polystyrene copolymer molecular chain, enhancing the bonding strength between the two, making the nano-titanium dioxide play a better reinforcing role, and further improving the tensile strength and elongation at break of polystyrene. And the rutile-type nano-titanium dioxide has a strong ultraviolet absorption ability, which is evenly dispersed in the polystyrene matrix, significantly improving its anti-ultraviolet aging performance.

[0071] Compared with Example 4, unmodified rutile-type nano-titanium dioxide was added in Comparative Example 3, and its compatibility with the polystyrene matrix was poor, and it did not contain isocyanate groups and could not react with the hydroxyl groups of the polystyrene copolymer, resulting in a low bonding strength between the two, leading to a low reinforcing effect of the nano-titanium dioxide, and the tensile strength and elongation at break of the polystyrene material were lower than those in Example 4.

[0072] The polystyrene in Comparative Example 4 did not contain hydroxyl groups and could not react with the isocyanate groups of the modified rutile-type nano-titanium dioxide, resulting in a low bonding strength between the two, leading to a poor reinforcing effect of the nano-titanium dioxide, and the tensile strength and elongation at break of the polystyrene material were lower than those in Example 4.

[0073] Weigh 6 mg of high-temperature resistant and anti-aging polystyrene, place it in a thermogravimetric analyzer, and conduct thermal performance tests in a nitrogen atmosphere at a heating rate of 10 °C / min and a test temperature range of 30 - 800 °C. The test results are shown in Table 3.

[0074] Table 3 Thermal Performance Test of Polystyrene

[0075]

[0076] As can be seen from the above table, compared with Comparative Example 4, the initial thermal decomposition temperature and the temperature of the maximum thermal decomposition rate of each of the Examples, as well as Comparative Examples 2 and 3, are significantly increased. This is mainly because the molecular chain of the polystyrene copolymer contains a diphenylsiloxane structure, which has strong heat resistance and good anti-thermal decomposition performance, and is conducive to improving the heat resistance of the material. Moreover, in each of the Examples, the isocyanate groups of the modified rutile-type nano-titanium dioxide react with the hydroxyl groups of the polystyrene copolymer, forming a chemical cross-linking effect between the nano-titanium dioxide and the polystyrene, increasing the cross-linking degree of the polystyrene molecular chain, restricting the movement of the molecular chain, thereby increasing the thermal decomposition temperature of the polystyrene material, showing a higher initial (5% mass loss) thermal decomposition temperature and the temperature of the maximum thermal decomposition rate, and significantly improving the high-temperature resistance of the material.

[0077] Some embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments.

Claims

1. Application of modified rutile nano-titanium dioxide in high temperature resistant and anti-aging polystyrene, characterized in that: The preparation method of the high temperature resistant and aging resistant polystyrene comprises the following steps: Step A, adding tetrahydrofuran, bis(4-aminophenoxy)dimethylsilane in a ratio of 1 g:(1.03-1.1) g, and glycidyl methacrylate into a reaction container, heating to 40-50° C., stirring for reaction for 3-5 hours, distilling under reduced pressure, washing, and drying to obtain acrylate dimethylsilane monomer; Step B, adding toluene, styrene, and acrylate dimethylsilane monomer into a reaction container, introducing nitrogen, adding azobisisobutyronitrile, distilling under reduced pressure after the reaction, washing, and drying to obtain a polystyrene copolymer; Step C, adding polystyrene copolymer, modified rutile nano-titanium dioxide and antioxidant into a twin-screw extruder, melt blending, extruding and granulating to obtain high temperature resistant and anti-aging polystyrene; In the step B, the mass ratio of styrene to acrylate dimethylsilane monomer is 1 g:(0.1-0.3) g; In the step C, the mass ratio of the polystyrene copolymer to the modified rutile nano-titanium dioxide is 100 g: (0.5-4) g; The preparation method of the modified rutile nano-titanium dioxide comprises the following steps: Step (1), adding water and titanium tetrachloride to a reaction vessel under an ice bath, stirring, adding n-hexanol and sodium dodecyl sulfate, stirring and mixing, pouring the solution into a reaction kettle, filtering after the reaction, washing, and drying to obtain rutile nano-titanium dioxide; Step (2), adding toluene and rutile nano-titanium dioxide into a reaction container, dispersing by ultrasonication, then adding toluene-2,4-diisocyanate, heating to 100-110° C., reacting for 2-3 hours, filtering, washing, and drying to obtain modified rutile nano-titanium dioxide.

2. The use of the modified rutile nano-titanium dioxide according to claim 1 in high temperature resistant and anti-aging polystyrene, characterized in that: The reaction temperature in step C is 70-85° C. and the reaction time is 7-10 h.

3. The use of the modified rutile nano-titanium dioxide according to claim 1 in high temperature resistant and anti-aging polystyrene, characterized in that: The temperature of sections 1-5 of the twin-screw extruder is 190-220°C.

4. The use of the modified rutile nano-titanium dioxide according to claim 1 in high temperature resistant and anti-aging polystyrene, characterized in that: In the step (1), the ratio of water, titanium tetrachloride, n-hexanol and sodium dodecyl sulfate is 1L:(120-200)g:(6-7)L:(80-130)g.

5. The use of the modified rutile nano-titanium dioxide in high temperature resistant and aging resistant polystyrene according to claim 1, characterized in that: The reaction temperature in step (1) is 80-100° C. and the reaction time is 12-18 hours.

6. The use of the modified rutile nano-titanium dioxide according to claim 1 in high temperature resistant and anti-aging polystyrene, characterized in that: In the step (2), the ratio of rutile nano-titanium dioxide to toluene-2,4-diisocyanate is 1 g:(0.4-1) g.

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