Flame-retardant microcellular foamed polypropylene board and preparation method thereof

Abstract

The present application relates to the technical field of polypropylene, and discloses a kind of flame-retardant microcellular polypropylene board and preparation method thereof, the raw material of polypropylene board of the present application includes the mass ratio of 100: (30-45): (1.7-2.2): (0.6-1) polypropylene, modified antimony trioxide, antioxidant;Raw materials are extruded into shape in double screw extruder, then in flat curing press, carbon dioxide is passed in, pressure holding foaming, obtain flame-retardant microcellular polypropylene board.2- (dicarboxymethyl) amino-4, 6- di (2, 4, 6-tribromoaniline) -1, 3, 5- triazine contains multiple bromine atoms, and antimony trioxide is compounded to form bromine antimony flame retardant, and contains a large number of nitrogen elements, can play the role of charring agent, further improve the flame retardant property of polypropylene, improve the limiting oxygen index.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polypropylene, in particular to a kind of flame-retardant microcellular polypropylene board and preparation method thereof. BACKGROUND

[0002] Polypropylene foam board has high mechanical strength, strong heat insulation performance, good insulation and corrosion resistance, and is widely used in construction, industry, agriculture, transportation and other fields. However, polypropylene foam board has poor flame retardancy and is easy to burn when exposed to fire, which hinders its practical application in fireproof building materials and other aspects. Currently, flame retardants for polypropylene include bromine-based flame retardants, antimony trioxide, magnesium hydroxide, aluminum hydroxide, and nitrogen-based flame retardants.

[0003] Antimony trioxide has gas-phase flame retardation and condensed-phase carbonization flame retardation effects, and can have a synergistic flame-retardant effect when compounded with bromine-based flame retardants. In order to improve the dispersibility and compatibility of antimony trioxide in polypropylene, it is usually necessary to modify antimony trioxide with oxystearic acid, aluminate coupling agent, silane coupling agent, etc. Nitrogen-based flame retardants have good carbonization effect, and can form an expanded carbon layer on the surface of polypropylene during combustion, thereby improving the flame retardancy. However, the use of nitrogen-based flame retardants alone cannot effectively improve the flame retardancy of polypropylene, and usually needs to be compounded with bromine-based flame retardants and inorganic flame retardants. SUMMARY

[0004] The present application solves the problems of poor compatibility of foamed antimony trioxide with polypropylene and poor flame retardancy of foamed polypropylene.

[0005] The technical solution of the present application is a kind of flame-retardant microcellular polypropylene board and preparation method thereof. The raw materials of the polypropylene board include polypropylene, modified antimony trioxide and antioxidant in a mass ratio of 100: (30-45): (1.7-2.2): (0.6-1).

[0006] The preparation method of the polypropylene board is as follows:

[0007] (1) Add water, 2-(dicarboxymethyl) amino-4,6-di(2,4,6-tribromo aniline)-1,3,5-triazine and antimony trioxide to a flask, heat and stir for surface modification, dry and remove water to obtain modified antimony trioxide.

[0008] (2) Mix polypropylene, modified antimony trioxide and antioxidant, and add them to a twin-screw extruder for extrusion molding. Then, pass carbon dioxide into a flat vulcanizing machine, pressurize and foam, and exhaust to obtain a flame-retardant microcellular polypropylene board.

[0009] Preferably, the temperature during heating and stirring in (1) is 75-90℃, and the time is 1-2h.

[0010] Preferably, the mass ratio of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromo aniline)-1,3,5-triazine to antimony trioxide in (1) is (22-32):(8-13).

[0011] Preferably, the antioxidant includes antioxidant 1010 and antioxidant 168.

[0012] Preferably, the temperature of the 1-6 segments of the twin-screw extruder is 130-185 DEG C, and the screw rotation speed is 200-350 r / min.

[0013] Preferably, the temperature of the flat plate vulcanizing machine is 150-160 DEG C, the carbon dioxide is introduced to control the pressure to be 10-12 MPa, and the pressure maintaining time is 2-2.5 h.

[0014] Preferably, the preparation method of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromo aniline)-1,3,5-triazine is as follows: 2-(dicarboxymethyl)amino-4,6-dichloro-1,3,5-triazine and 2,4,6-tribromo aniline are added into 1,4-dioxane in a molar ratio of 1:(2-2.4), heated to 50-60 DEG C, stirred for 12-18 h, sodium bicarbonate aqueous solution is added dropwise during the reaction to maintain the pH of the reaction solution to be 8-9, hydrochloric acid solution is added dropwise after the reaction, the precipitate is recrystallized in ethanol after filtration, and 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromo aniline)-1,3,5-triazine is obtained.

[0015] The 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromo aniline)-1,3,5-triazine prepared in the application contains multiple carboxyl groups, can form interaction with the surface of antimony trioxide, realizes surface modification of antimony trioxide, and then is blended and foamed with polypropylene, etc., to obtain a flame-retardant microcellular polypropylene plate. The dispersion of the modified antimony trioxide is good, is not easy to agglomerate in polypropylene, has little influence on the mechanical properties of the foamed polypropylene plate, and makes the foamed plate maintain good tensile strength and compression strength.

[0016] The 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromo aniline)-1,3,5-triazine of the application contains multiple bromine atoms, forms a bromine-antimony flame retardant when compounded with antimony trioxide, significantly improves the flame-retardant properties of the polypropylene plate, and contains a large amount of nitrogen elements, can play a role of a charring agent, further improves the flame-retardant properties of polypropylene, and improves the limiting oxygen index. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0018] According to the method of the master's degree thesis of Suzhou University, "Research on Environment-friendly Anti-wrinkle Finishing Agent for Silk", cyanuric chloride, iminodiacetic acid and sodium hydroxide are reacted in a molar ratio of 1:0.8:2.44 to obtain 2-(dicarboxymethyl)amino-4,6-dichloro-1,3,5-triazine, and the structural formula is .

[0019] Example 1: (1) 0.2 mol of 2-(dicarboxymethyl)amino-4,6-dichloro-1,3,5-triazine and 0.4 mol of 2,4,6-tribromoaniline are added to 800 mL of 1,4-dioxane, heated to 50°C, and stirred for 18 h. During the reaction, sodium bicarbonate aqueous solution is added dropwise to maintain the pH of the reaction solution at 9. After the reaction, hydrochloric acid solution is added dropwise to adjust the pH to 3. After filtration, the precipitate is recrystallized in ethanol to obtain 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine. The reaction formula is:

[0020] .

[0021] (2) 1.2 L of water, 220 g of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine, and 80 g of modified antimony trioxide are added to a flask, heated to 80°C, and stirred for 1 h. After drying, modified antimony trioxide is obtained.

[0022] (3) 1 kg of polypropylene (model Zhenhai Refining and Chemical E02Es, same below), 300 g of modified antimony trioxide, and 9 g of antioxidant 1010 are mixed and added to a double-screw extruder. The temperature of 1-6 segments is 130°C, 150°C, 165°C, 180°C, 185°C, and 185°C. The screw rotation speed is 350 r / min. Extrusion molding is performed, and then in a flat vulcanizing machine, the temperature is 150°C, and carbon dioxide is introduced to control the pressure to 12 MPa. Pressure foaming is performed for 2.5 h, exhaust is performed, and flame-retardant microcellular foamed polypropylene plates are obtained.

[0023] Example 2: (1) To 900 mL of 1,4-dioxane, 0.2 mol of 2-(dicarboxymethyl)amino-4,6-dichloro-1,3,5-triazine, 0.44 mol of 2,4,6-tribromoaniline were added, heated to 60°C, stirred for 12 h, and during the reaction, an aqueous sodium bicarbonate solution was added dropwise to maintain the pH of the reaction solution at 8. After the reaction, a hydrochloric acid solution was added dropwise to adjust the pH to 2. After filtration, the precipitate was recrystallized in ethanol to obtain 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine.

[0024] (2) To a flask, 1.5 L of water, 245 g of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine, 95 g of antimony trioxide were added, heated to 75°C, stirred for 2 h, and dried to remove water to obtain modified antimony trioxide.

[0025] (3) 1 kg of polypropylene, 350 g of modified antimony trioxide, and 10 g of antioxidant 1010 were mixed and added to a twin-screw extruder. The temperatures of 1-6 segments were 130°C, 150°C, 165°C, 180°C, 185°C, and 185°C, and the screw rotation speed was 200 r / min. Extrusion molding was then performed in a flat vulcanizing machine at a temperature of 160°C, with carbon dioxide being introduced to control the pressure to 12 MPa, and pressure foaming was performed for 2 h. After exhausting, a flame-retardant microcellular foamed polypropylene plate was obtained.

[0026] Example 3: (1) To a flask, 1.5 L of water, 290 g of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine (prepared according to the method of Example 1), 110 g of antimony trioxide were added, heated to 75°C, stirred for 2 h, and dried to remove water to obtain modified antimony trioxide.

[0027] (2) 1 kg of polypropylene, 400 g of modified antimony trioxide, and 6.8 g of antioxidant 168 were mixed and added to a twin-screw extruder. The temperatures of 1-6 segments were 130°C, 150°C, 165°C, 180°C, 185°C, and 185°C, and the screw rotation speed was 300 r / min. Extrusion molding was then performed in a flat vulcanizing machine at a temperature of 160°C, with carbon dioxide being introduced to control the pressure to 10 MPa, and pressure foaming was performed for 2.5 h. After exhausting, a flame-retardant microcellular foamed polypropylene plate was obtained.

[0028] Example 4: (1) To a flask, 1.8 L of water, 320 g of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine (prepared according to the method of Example 1), 130 g of antimony trioxide were added, heated to 90°C, stirred for 1.5 h, and dried to remove water to obtain modified antimony trioxide.

[0029] (2) Mix 1kg of polypropylene, 450g of modified antimony trioxide and 6g of antioxidant 168 and add them to a twin-screw extruder. The temperatures of sections 1-6 are 130℃, 150℃, 165℃, 180℃, 185℃ and 185℃ respectively. The screw speed is 350r / min. Extrusion molding is performed and then the product is placed in a flat vulcanizing machine at a temperature of 160℃. Carbon dioxide is introduced and the pressure is controlled at 12MPa. The product is kept under pressure for 2 hours and then the air is vented to obtain flame-retardant microporous foamed polypropylene sheet.

[0030] Comparative Example 1

[0031] (1) Mix 1kg of polypropylene, 80g of antimony trioxide and 9g of antioxidant 1010 and add them to a twin-screw extruder. The temperatures of sections 1-6 are 130℃, 150℃, 165℃, 180℃, 185℃ and 185℃ respectively. The screw speed is 350r / min. Extrusion molding is performed and then the product is placed in a flat vulcanizing machine at 150℃. Carbon dioxide is introduced and the pressure is controlled at 12MPa. The product is kept under pressure for 2.5h and then the air is vented to obtain microporous foamed polypropylene sheets.

[0032] Comparative Example 2

[0033] (1) Add 1.2L of water, 220g of decabromodiphenyl ethane and 80g of antimony trioxide to a flask, heat to 80℃, stir for 1h, dry to remove water, and obtain a blend of decabromodiphenyl ethane and antimony trioxide.

[0034] (2) Mix 1 kg of polypropylene, 300 g of decabromodiphenyl ethane-antimony trioxide blend and 9 g of antioxidant 1010, add them to a twin-screw extruder, set the temperatures of sections 1-6 to 130℃, 150℃, 165℃, 180℃, 185℃ and 185℃ respectively, and set the screw speed to 350 r / min. Extrude the mixture and then in a flat vulcanizing machine at 150℃, introduce carbon dioxide and control the pressure to 12 MPa. Hold the pressure and foam for 2.5 h, then exhaust the gas to obtain microporous foamed polypropylene sheets.

[0035] Comparative Example 3

[0036] (1) Add 1.2L of water, 220g of stearic acid and 80g of antimony trioxide to a flask, heat to 80℃, stir for 1 h, dry to remove water, and obtain modified antimony trioxide.

[0037] (2) Mix 1kg of polypropylene, 300g of modified antimony trioxide and 9g of antioxidant 1010 and add them to a twin-screw extruder. The temperatures of sections 1-6 are 130℃, 150℃, 165℃, 180℃, 185℃ and 185℃ respectively. The screw speed is 350r / min. Extrusion molding is performed and then the product is placed in a flat vulcanizing machine at 150℃. Carbon dioxide is introduced and the pressure is controlled at 12MPa. The product is kept under pressure for 2.5h and then the air is vented to obtain microporous foamed polypropylene sheets.

[0038] Comparative Example 4

[0039] (1) 1 kg of polypropylene, 220 g of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine, 80 g of antimony trioxide, and 9 g of antioxidant 1010 were mixed and added to a twin-screw extruder. The temperature of the 1-6 segments was 130°C, 150°C, 165°C, 180°C, 185°C, and 185°C, and the screw rotation speed was 350 r / min. Extrusion molding was performed, and then, in a flat vulcanizing machine, the temperature was 150°C, and carbon dioxide was introduced to control the pressure to 12 MPa. Foaming was performed for 2.5 h under pressure, exhaust was performed, and a microcellular foamed polypropylene plate was obtained.

[0040] The oxygen index was tested according to the standard GB / T 2406.1-2008. The tensile strength was tested according to the standard GB / T 9641-1988. The compressive strength was tested according to the standard GB / T 8813-2020.

[0041] Table 1 Properties of polypropylene plates

[0042]

[0043] Compared with Comparative Example 1, Example 1 uses 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine containing carboxyl to modify antimony trioxide. The modified antimony trioxide has good dispersibility and is not easy to agglomerate in polypropylene, has little effect on the mechanical properties of the foamed polypropylene plate, and makes the foamed plate maintain good tensile strength and compressive strength. Moreover, 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine contains multiple bromine atoms, and forms a bromine-antimony flame retardant with antimony trioxide, which significantly improves the flame retardant properties of the polypropylene plate. Moreover, it contains a large amount of nitrogen elements, which can play a role as a charring agent, further improving the flame retardant properties of polypropylene and increasing the limiting oxygen index.

[0044] Comparative Example 2 uses decabromodiphenyl ethane, which does not contain carboxyl, to modify antimony trioxide. The dispersibility of antimony trioxide is not good, and it is easy to agglomerate in polypropylene, which has a great effect on the mechanical properties of the foamed polypropylene plate, resulting in low tensile strength and compressive strength. Moreover, decabromodiphenyl ethane does not contain nitrogen elements, and its flame retardant performance is lower than that of 2-(dicarboxymethyl)amino-4,6-di(2,4,6-tribromoaniline)-1,3,5-triazine, resulting in a lower limiting oxygen index than Example 1.

[0045] Comparative Example 3 uses conventional stearic acid to modify antimony trioxide. Stearic acid does not have flame retardant properties, resulting in a very low limiting oxygen index of the foamed polypropylene plate.

[0046] Comparative Example 4 directly blends polypropylene, 2-(dicarboxymethyl) amino-4, 6-di(2, 4, 6-tribromoaniline)-1, 3, 5-triazine and antimony trioxide to foam, without surface modification of the antimony trioxide, and the dispersion of the antimony trioxide is not good, and the antimony trioxide is easy to agglomerate in the polypropylene, which has a great influence on the mechanical properties of the foamed polypropylene plate, resulting in low tensile strength and compression strength.

[0047] The above description is merely preferred embodiments of the present application, but not a limitation of the present application. Any modification or equivalent replacement made by those skilled in the art based on the above disclosure is within the scope of the present application.

Claims

1. A flame-retardant microporous foamed polypropylene sheet, characterized in that, The raw materials for the polypropylene sheet include polypropylene, modified antimony trioxide, and antioxidants in a mass ratio of 100:(30-45):(1.7-2.2):(0.6-1). The modified antimony trioxide is prepared by adding water, 2-(dicarboxymethyl)amino-4,6-bis(2,4,6-tribromoaniline)-1,3,5-triazine, and antimony trioxide to a flask, heating and stirring to carry out surface modification, drying to remove water, and obtaining modified antimony trioxide. The method for preparing the flame-retardant microporous foamed polypropylene sheet is as follows: polypropylene, modified antimony trioxide, and antioxidant are mixed and added to a twin-screw extruder for extrusion molding. Then, carbon dioxide is introduced into a flat vulcanizing machine for pressure foaming and degassing to obtain the flame-retardant microporous foamed polypropylene sheet.

2. The flame-retardant microporous foamed polypropylene sheet according to claim 1, characterized in that, The antioxidants include antioxidant 1010 and antioxidant 168.

3. The flame-retardant microporous foamed polypropylene sheet according to claim 1, characterized in that, The temperature during heating and stirring is 75-90℃, and the time is 1-2 hours.

4. The flame-retardant microporous foamed polypropylene sheet according to claim 1, characterized in that, The mass ratio of 2-(dicarboxymethyl)amino-4,6-bis(2,4,6-tribromoaniline)-1,3,5-triazine to antimony trioxide is (22-32):(8-13).

5. The flame-retardant microporous foamed polypropylene sheet according to claim 1, characterized in that, The preparation method of 2-(dicarboxymethyl)amino-4,6-bis(2,4,6-tribromoaniline)-1,3,5-triazine is as follows: 2-(dicarboxymethyl)amino-4,6-dichloro-1,3,5-triazine and 2,4,6-tribromoaniline are added to 1,4-dioxane, heated to 50-60℃, and stirred for 12-18 hours. Sodium bicarbonate aqueous solution is added dropwise during the reaction, and hydrochloric acid solution is added dropwise after the reaction. After filtration, recrystallization is performed to obtain 2-(dicarboxymethyl)amino-4,6-bis(2,4,6-tribromoaniline)-1,3,5-triazine.

6. The flame-retardant microporous foamed polypropylene sheet according to claim 5, characterized in that, The molar ratio of 2-(dicarboxymethyl)amino-4,6-dichloro-1,3,5-triazine and 2,4,6-tribromoaniline is 1:(2-2.4).

7. The flame-retardant microporous foamed polypropylene sheet according to claim 5, characterized in that, The addition of sodium bicarbonate aqueous solution maintains the pH of the reaction solution at 8-9.

8. A method for preparing a flame-retardant microporous foamed polypropylene sheet as described in any one of claims 1-7, characterized in that, The preparation method is as follows: polypropylene, modified antimony trioxide, and antioxidant are mixed and added to a twin-screw extruder for extrusion molding. Then, carbon dioxide is introduced into a flat vulcanizing machine for pressure foaming and degassing to obtain flame-retardant microporous foamed polypropylene sheet.

9. The method for preparing flame-retardant microporous foamed polypropylene sheet according to claim 8, characterized in that, The temperature of sections 1-6 of the twin-screw extruder is 130-185℃, and the screw speed is 200-350 r / min.

10. The method for preparing flame-retardant microporous foamed polypropylene sheet according to claim 8, characterized in that, The temperature of the flat vulcanizing machine is 150-160℃, the carbon dioxide pressure is controlled at 10-12MPa, and the pressure holding time is 2-2.5h.

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