Preparation process of polystyrene flame-retardant insulation board

Abstract

The invention relates to the technical field of polystyrene, and discloses a preparation process of a polystyrene flame-retardant insulation board, which comprises the following steps: mixing polystyrene resin, a polystyrene resin-based flame retardant, aminated silica aerogel, a foaming agent, a nucleating agent and the like in an extruder, and extruding and foaming to obtain the polystyrene flame-retardant insulation board. The silicon dioxide aerogel is uniformly dispersed in the polystyrene insulation board, so that the heat conductivity coefficient of the insulation board is reduced, and the insulation performance is improved. The polystyrene-based flame retardant contains a nitrogen-containing structure of triazole and a large number of phosphate structures of dioxaphosphorus heterocycles, a nitrogen-phosphorus flame retardant is formed, a very good condensed phase flame retardant effect is achieved, the limit oxygen index of the insulation board is increased, and the insulation board has better flame retardant performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polystyrene, and specifically to a preparation process of a polystyrene flame-retardant thermal insulation board. Background Art

[0002] After polystyrene is foamed, the obtained polystyrene foam has large porosity, low thermal conductivity, good thermal insulation performance and excellent mechanical properties, and is widely used in thermal insulation boards, building materials, etc. However, polystyrene foam boards have disadvantages such as easy flammability, which limits the practical application of polystyrene thermal insulation boards in fireproof materials, etc. Usually, adding flame retardants to the foam board can solve the above problems. Common flame retardants include inorganic flame retardants, nitrogen-phosphorus flame retardants, brominated flame retardants, etc. Among them, nitrogen-phosphorus halogen-free flame retardants have the advantages of being green and environmentally friendly, having a small addition amount, and good flame retardant effect. Developing new nitrogen-phosphorus halogen-free flame retardants is a research hotspot.

[0003] Silica aerogel is a class of porous nano-solid materials with low density and light weight, and has very low thermal conductivity, and has important applications in thermal insulation materials, flame retardant materials, etc. Adding silica aerogel to polystyrene foam materials can obtain new thermal insulation materials with lower thermal conductivity. However, the compatibility between silica aerogel and polystyrene is poor, and adding it to polystyrene foam materials will affect their mechanical properties. Patent CN113736184B discloses a high-strength flame-retardant thermal insulation board and its preparation method, using polystyrene, modified silica aerogel, modified expanded graphite, microencapsulated red phosphorus, etc. as raw materials, and the obtained thermal insulation board has the advantages of high strength and good flame retardancy. Compared with this invention, the present invention improves the compatibility between silica aerogel and polystyrene resin, and improves the mechanical properties and thermal insulation performance of polystyrene thermal insulation boards. Summary of the Invention

[0004] Technical problem to be solved: The present invention provides a polystyrene flame-retardant thermal insulation board with good mechanical properties, excellent flame retardant properties and low thermal conductivity.

[0005] Technical solution: A preparation process of a polystyrene flame-retardant thermal insulation board includes the following steps: Step (1), adding a flame retardant intermediate with the structural formula and azobisisobutyronitrile to toluene, heating to 75 - 85 °C in a nitrogen atmosphere, stirring and reacting for 18 - 24 h, concentrating under reduced pressure, filtering, and washing with ethanol to obtain a polystyrene-based flame retardant.

[0006] Step (2): Add 100 parts by weight of polystyrene resin, 8 - 25 parts by weight of polystyrene resin - based flame retardant, 1 - 5 parts by weight of aminated silica aerogel, 0.6 - 0.9 parts by weight of foaming agent azodicarbonamide or diisopropyl azodicarboxylate, 0.5 - 0.7 parts by weight of antioxidant antioxidant 1010, antioxidant 1076 or antioxidant 168, and 2.5 - 4 parts by weight of nucleating agent talc into a twin - screw extruder for melt extrusion, and then perform foam extrusion molding in a single - screw extruder to obtain a polystyrene flame - retardant thermal insulation board.

[0007] Further, in step (1), the mass ratio of the flame retardant intermediate to azodiisobutyronitrile is 1:(0.003 - 0.004).

[0008] Further, in step (2), the temperature of zones 1 - 6 of the twin - screw extruder is 180 - 220 °C, and the screw speed is 50 - 100 r / min; the temperature of zones 1 - 3 of the single - screw extruder is 80 - 125 °C, and the screw speed is 50 - 80 r / min.

[0009] Further, the preparation process of the aminated silica aerogel is as follows: Add tetraethyl orthosilicate to ethanol, stir and then dropwise add hydrochloric acid solution to adjust the pH to 3 - 3.5, heat to 60 - 65 °C, stir and react for 1.5 - 2.5 h, cool and then add N,N - dimethylformamide, stir and then dropwise add an ethanol solution containing 3 - aminopropyltriethoxysilane, where the mass ratio of tetraethyl orthosilicate to 3 - aminopropyltriethoxysilane is 1:(0.7 - 1.1), stir and then pour into a mold, let stand for gelation, then pour the gel into ethanol, heat to 40 - 50 °C, age for 18 - 24 h, take out the gel, wash successively with ethanol and petroleum ether, and dry to obtain the aminated silica aerogel.

[0010] Step S1: Add 5 - carboxy - 3 - amino - 1,2,4 - triazole, 4 - vinylbenzaldehyde, and glacial acetic acid with a mass ratio of (0.97 - 1.07):1:(0.76 - 0.84) to ethanol, heat to 75 - 80 °C, carry out condensation reflux reaction for 3 - 5 h, cool and then filter, add the precipitate to ethanol, add sodium borohydride, stir and react for 3 - 4 h, heat to volatilize, cool and crystallize, wash with water, and dry to obtain intermediate A. The reaction formula is: 。

[0011] Step S2: Add intermediate A, 5,5 - dimethyl - 1,3,2 - dioxaphosphorinane - 2 - one, and triethylamine with a mass ratio of 1:(1.52 - 1.81):(0.83 - 0.91) to dichloromethane, stir and react at 20 - 30 °C for 12 - 18 h, heat to volatilize, cool and crystallize, wash successively with water and acetone, and dry to obtain the flame retardant intermediate. The reaction formula is: 。

[0012] (III) Beneficial effects: In the present invention, tetraethyl orthosilicate and 3-aminopropyltriethoxysilane are subjected to co-hydrolysis reaction to obtain amino-containing silica aerogel. Further, azobisisobutyronitrile is used as an initiator to initiate the polymerization reaction of a flame retardant intermediate containing a styrene structure, obtaining a polystyrene-based flame retardant containing a nitrogen-containing structure of triazole and a large number of phosphate structures of dioxaphospholane rings. Then, it is melt-blended and extruded and foamed with polystyrene resin, amino-functionalized silica aerogel, polystyrene-based flame retardant, foaming agent, etc. in a single-screw extruder to obtain a polystyrene flame-retardant thermal insulation board.

[0013] During the high-temperature melting process, the carboxyl group of the polystyrene-based flame retardant can react with the amino group of the silica aerogel, thereby grafting polystyrene-like molecular chains on the surface of the silica aerogel, improving the compatibility between the silica aerogel and the polystyrene resin, with excellent dispersion of the aerogel and less impact on the mechanical properties of the thermal insulation board, enabling the thermal insulation board to maintain good impact strength and mechanical properties.

[0014] The silica aerogel of the present invention is uniformly dispersed in the polystyrene thermal insulation board, which is beneficial to reducing the thermal conductivity of the thermal insulation board and improving the thermal insulation performance. The polystyrene-based flame retardant of the present invention contains a nitrogen-containing structure of triazole and a large number of phosphate structures of dioxaphospholane rings, forming a nitrogen-phosphorus flame retardant, which plays a good condensed-phase flame retardant effect, improves the limiting oxygen index of the thermal insulation board, and has better flame retardant performance. Description of the Drawings

[0015] Figure 1 is the 1H NMR spectrum of the flame retardant intermediate.

[0016] Figure 2 is the infrared spectrum of the polystyrene-based flame retardant.

[0017] Figure 3 is the infrared spectrum of the amino-functionalized silica aerogel. Detailed Embodiments

[0018] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the preferred implementation schemes of the present invention are described below in conjunction with specific embodiments. The test methods or testing methods described in the following embodiments are all conventional methods unless otherwise specified; the reagents and materials are all obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0019] Example 1: (1) Add 21.4 g of 5-carboxy-3-amino-1,2,4-triazole, 20 g of 4-vinylbenzaldehyde, and 15.2 g of glacial acetic acid to 800 mL of ethanol. Heat to 80 °C and reflux for 5 h. After cooling, filter. Add the precipitate to ethanol, add 6.2 g of sodium borohydride, stir and react for 4 h, heat to evaporate, cool and crystallize, wash with water, and dry to obtain Intermediate A.

[0020] (2) Add 10 g of Intermediate A, 15.2 g of 5,5-dimethyl-1,3,2-dioxaphosphorinane-2-oxide chloride, and 8.3 g of triethylamine to 200 mL of dichloromethane. Stir and react at 30 °C for 12 h. Heat to evaporate, cool and crystallize, wash successively with water and acetone, and dry to obtain the flame retardant intermediate. Figure 1 The 1H NMR spectrum of shows that the chemical shift values of the flame retardant intermediate are: 11.09 (s, 1H), 8.08 (m, 2H), 7.71 (m, 2H), 6.08 (m, 1H), 5.73 (m, 1H), 5.41 (m, 1H), 4.96 - 4.85 (m, 2H), 4.32 - 4.09 (m, 8H), 3.09 (s, 6H), 2.96 (s, 6H).

[0021] (3) Add 40 g of the flame retardant intermediate and 0.13 g of azobisisobutyronitrile to 140 mL of toluene. Under a nitrogen atmosphere, heat to 80 °C and stir and react for 18 h. Concentrate under reduced pressure, filter, and wash with ethanol to obtain the polystyrene-based flame retardant. Figure 2 The infrared spectrum of shows that 2972 cm -1 and 1477 cm -1 are the vibration absorption peaks of C-H and CH 2 in the polystyrene molecular chain respectively. 3254 cm -1 is the absorption peak of carboxyl -OH. 1624 cm -1 is the absorption peak of the C=N bond in triazole. 1176 cm -1 and 1058 cm -1 are the absorption peaks of the P=O bond and P-O-C bond in the phosphate ester group respectively. It shows that the flame retardant intermediate undergoes a polymerization reaction to form the polystyrene-based flame retardant.

[0022] (4) Add 20 g of tetraethyl orthosilicate to 20 mL of ethanol. After stirring, add a 0.4% hydrochloric acid solution by dropping to adjust the pH to 3. Heat to 65 °C and stir for 2 h. After cooling, add 3 mL of N,N-dimethylformamide. After stirring, add 40 mL of an ethanol solution containing 17 g of 3-aminopropyltriethoxysilane. After stirring, pour it into a mold and let it stand for gelation. Then pour the gel into 100 mL of ethanol, heat to 40 °C, and age for 24 h. Take out the gel, wash it successively with ethanol and petroleum ether, and dry it to obtain amino-functionalized silica aerogel. Figure 3 The infrared spectrum shows that at 1176 cm -1 to 1232 cm -1 is the absorption peak of the S-O bond of silica. At 1512 cm -1 and 697 cm -1 are the characteristic absorption peaks of the amino group. It can be seen that amino groups are introduced on the surface of the silica aerogel.

[0023] (5) Add 1 kg of polystyrene resin, 80 g of polystyrene-based flame retardant, 10 g of amino-functionalized silica aerogel, 6.8 g of blowing agent azodicarbonamide, 5.7 g of antioxidant 1076, and 40 g of nucleating agent talc powder into a twin-screw extruder for melt extrusion. The temperatures of zones 1-6 are 180 °C, 195 °C, 210 °C, 220 °C, 220 °C, and 210 °C, and the screw speed is 100 r / min; then extrude and foam in a single-screw extruder. The temperatures of zones 1-3 are 180 °C, 205 °C, and 225 °C, and the screw speed is 80 r / min to obtain a polystyrene flame-retardant and heat-insulating board.

[0024] Example 2: (1) Add 19.4 g of 5-carboxy-3-amino-1,2,4-triazole, 20 g of 4-vinylbenzaldehyde, and 16.8 g of glacial acetic acid to 600 mL of ethanol. Heat to 75 °C and carry out a condensation reflux reaction for 3 h. After cooling, filter. Add the precipitate to ethanol, add 6.5 g of sodium borohydride, stir for 3 h, heat to evaporate, cool and crystallize, wash with water, and dry to obtain intermediate A.

[0025] (2) Add 10 g of intermediate A, 18.1 g of 5,5-dimethyl-1,3,2-dioxaphosphorinane-2-oxide, and 9.1 g of triethylamine to 250 mL of dichloromethane. Stir at 20 °C for 18 h, heat to evaporate, cool and crystallize, wash successively with water and acetone, and dry to obtain a flame retardant intermediate.

[0026] (3) Add 40 g of the flame retardant intermediate and 0.12 g of azobisisobutyronitrile to 120 mL of toluene. In a nitrogen atmosphere, heat to 85 °C and stir for 18 h. Concentrate under reduced pressure, filter, and wash with ethanol to obtain a polystyrene-based flame retardant.

[0027] (4) Add 20 g of tetraethyl orthosilicate to 30 mL of ethanol. After stirring, add a 0.4% hydrochloric acid solution by dropwise addition to adjust the pH to 3. Heat to 65 °C and stir for 2 h. After cooling, add 3 mL of N,N-dimethylformamide. After stirring, add 40 mL of an ethanol solution containing 22 g of 3-aminopropyltriethoxysilane. After stirring, pour it into a mold and let it stand for gelation. Then pour the gel into 100 mL of ethanol, heat to 40 °C, and age for 24 h. Take out the gel and wash it successively with ethanol and petroleum ether, and then dry it to obtain amino-functionalized silica aerogel.

[0028] (5) Add 1 kg of polystyrene resin, 140 g of polystyrene-based flame retardant, 20 g of amino-functionalized silica aerogel, 6 g of blowing agent azodicarbonamide, 5.7 g of antioxidant 1010, and 40 g of nucleating agent talc powder to a twin-screw extruder for melt extrusion. The temperatures in zones 1-6 are 180 °C, 195 °C, 210 °C, 220 °C, 220 °C, and 210 °C, and the screw speed is 100 r / min. Then, it is extruded and foamed in a single-screw extruder. The temperatures in zones 1-3 are 180 °C, 205 °C, and 225 °C, and the screw speed is 50 r / min to obtain a polystyrene flame-retardant and heat-insulating board.

[0029] Example 3: (1) Add 40 g of the flame retardant intermediate (prepared in Example 1) and 0.16 g of azobisisobutyronitrile to 150 mL of toluene. Under a nitrogen atmosphere, heat to 75 °C and stir for 18 h. Concentrate under reduced pressure, filter, and wash with ethanol to obtain a polystyrene-based flame retardant.

[0030] (2) Add 20 g of tetraethyl orthosilicate to 25 mL of ethanol. After stirring, add a 0.4% hydrochloric acid solution by dropwise addition to adjust the pH to 3.5. Heat to 60 °C and stir for 2.5 h. After cooling, add 4 mL of N,N-dimethylformamide. After stirring, add 40 mL of an ethanol solution containing 14 g of 3-aminopropyltriethoxysilane. After stirring, pour it into a mold and let it stand for gelation. Then pour the gel into 100 mL of ethanol, heat to 45 °C, and age for 18 h. Take out the gel and wash it successively with ethanol and petroleum ether, and then dry it to obtain amino-functionalized silica aerogel.

[0031] (3) Add 1 kg of polystyrene resin, 200 g of polystyrene-based flame retardant, 35 g of aminated silica aerogel, 9 g of blowing agent diisopropyl azodicarboxylate, 7 g of antioxidant 1076, and 25 g of nucleating agent talc powder into a twin-screw extruder for melt extrusion. The temperatures in zones 1-6 are 180 °C, 195 °C, 210 °C, 220 °C, 220 °C, and 210 °C, and the screw speed is 50 r / min. Then, perform foam molding in a single-screw extruder. The temperatures in zones 1-3 are 180 °C, 205 °C, and 225 °C, and the screw speed is 50 r / min to obtain a polystyrene flame-retardant thermal insulation board.

[0032] Example 4: (1) Add 40 g of flame retardant intermediate (prepared in Example 1) and 0.12 g of azobisisobutyronitrile to 150 mL of toluene. Under a nitrogen atmosphere, heat to 80 °C and stir for 24 h. Concentrate under reduced pressure, filter, and wash with ethanol to obtain a polystyrene-based flame retardant.

[0033] (2) Add 20 g of tetraethyl orthosilicate to 30 mL of ethanol. After stirring, add a 0.4% hydrochloric acid solution by mass fraction to adjust the pH to 3. Heat to 65 °C and stir for 1.5 h. After cooling, add 3 mL of N,N-dimethylformamide. After stirring, add 45 mL of an ethanol solution containing 20 g of 3-aminopropyltriethoxysilane. After stirring, pour it into a mold and let it stand for gelation. Then, pour the gel into 100 mL of ethanol, heat to 50 °C, and age for 18 h. Take out the gel and wash it successively with ethanol and petroleum ether, and dry it to obtain aminated silica aerogel.

[0034] (3) Add 1 kg of polystyrene resin, 250 g of polystyrene-based flame retardant, 50 g of aminated silica aerogel, 8.2 g of blowing agent azodicarbonamide, 5 g of antioxidant 168, and 30 g of nucleating agent talc powder into a twin-screw extruder for melt extrusion. The temperatures in zones 1-6 are 180 °C, 195 °C, 210 °C, 220 °C, 220 °C, and 210 °C, and the screw speed is 50 r / min. Then, perform foam molding in a single-screw extruder. The temperatures in zones 1-3 are 180 °C, 205 °C, and 225 °C, and the screw speed is 80 r / min to obtain a polystyrene flame-retardant thermal insulation board.

[0035] Comparative Example 1. The difference between this comparative example and Example 1 is that no polystyrene-based flame retardant is added.

[0036] (1) Add 1 kg of polystyrene resin, 10 g of aminated silica aerogel, 6.8 g of foaming agent azodicarbonamide, 5.7 g of antioxidant 1076, and 40 g of nucleating agent talc powder into a twin-screw extruder for melt extrusion. The temperatures in zones 1 - 6 are 180 °C, 195 °C, 210 °C, 220 °C, 220 °C, 210 °C, and the screw speed is 100 r / min. Then, perform foam extrusion molding in a single-screw extruder. The temperatures in zones 1 - 3 are 180 °C, 205 °C, 225 °C, and the screw speed is 80 r / min to obtain a polystyrene flame-retardant insulation board.

[0037] Comparative Example 2. The difference between this comparative example and Example 1 is that an intermediate A is used to prepare a polystyrene-based flame retardant.

[0038] (1) Add 40 g of intermediate A and 0.13 g of azobisisobutyronitrile to 140 mL of toluene. Under a nitrogen atmosphere, heat to 80 °C and stir for 18 h. Concentrate under reduced pressure, filter, and wash with ethanol to obtain a polystyrene-based flame retardant.

[0039] (2) Add 1 kg of polystyrene resin, 80 g of polystyrene-based flame retardant, 10 g of aminated silica aerogel, 6.8 g of foaming agent azodicarbonamide, 5.7 g of antioxidant 1076, and 40 g of nucleating agent talc powder into a twin-screw extruder for melt extrusion. The temperatures in zones 1 - 6 are 180 °C, 195 °C, 210 °C, 220 °C, 220 °C, 210 °C, and the screw speed is 100 r / min. Then, perform foam extrusion molding in a single-screw extruder. The temperatures in zones 1 - 3 are 180 °C, 205 °C, 225 °C, and the screw speed is 80 r / min to obtain a polystyrene flame-retardant insulation board.

[0040] Comparative Example 3. The difference between this comparative example and Example 1 is that when preparing silica aerogel, 3-aminopropyltriethoxysilane is not added.

[0041] (1) Add 20 g of tetraethyl orthosilicate to 20 mL of ethanol. After stirring, add a 0.4% hydrochloric acid solution by mass to adjust the pH to 3. Heat to 65 °C and stir for 2 h. After cooling, add 3 mL of N,N-dimethylformamide, stir and pour into a mold, let it stand for gelation. Then, pour the gel into 100 mL of ethanol, heat to 40 °C, and age for 24 h. Take out the gel and wash it successively with ethanol and petroleum ether, and dry it to obtain silica aerogel.

[0042] (2) 1 kg of polystyrene resin, 80 g of polystyrene-based flame retardant, 10 g of silica aerogel, 6.8 g of blowing agent azodicarbonamide, 5.7 g of antioxidant 1076, and 40 g of nucleating agent talc were added to a twin-screw extruder for melt extrusion. The temperatures in zones 1-6 were 180 °C, 195 °C, 210 °C, 220 °C, 220 °C, and 210 °C, and the screw speed was 100 r / min. Then, it was extruded and foamed in a single-screw extruder. The temperatures in zones 1-3 were 180 °C, 205 °C, and 225 °C, and the screw speed was 80 r / min to obtain a polystyrene flame-retardant thermal insulation board.

[0043] The compression performance of the polystyrene flame-retardant thermal insulation board was tested according to the method of GB / T 8813-2020.

[0044] The flame retardancy was tested according to GB / T 2406.2-2009 Plastics - Determination of burning behavior by the oxygen index method - Part 2: Room temperature test method.

[0045] The pore size and porosity of the polystyrene flame-retardant thermal insulation board were tested using a mercury intrusion pore size analyzer.

[0046] The thermal conductivity was tested with reference to GB / T 10294-2008 Thermal insulation materials - Determination of steady-state thermal resistance and related properties - Guarded hot plate method.

[0047] Table 1

[0048] Table 1 shows that the limiting oxygen index of the polystyrene flame-retardant thermal insulation boards in Examples 1-4 reached over 27.9%, and they had a large porosity, low thermal conductivity, good thermal insulation performance, high compressive strength, and excellent mechanical properties. This is because the addition of the polystyrene-based flame retardant and amino-functionalized silica aerogel allows the carboxyl group of the polystyrene-based flame retardant to react with the amino group of the silica aerogel during the high-temperature melting process in the extruder, thereby grafting polystyrene molecular chains onto the surface of the silica aerogel, improving the compatibility between the silica aerogel and the polystyrene resin. The aerogel is well-dispersed, having less impact on the mechanical properties of the thermal insulation board, enabling the thermal insulation board to maintain good impact strength and mechanical properties. At the same time, the silica aerogel is uniformly dispersed in the polystyrene thermal insulation board, which is beneficial to reducing the thermal conductivity of the thermal insulation board and improving its thermal insulation performance. The polystyrene-based flame retardant contains a nitrogen-containing structure with triazole and a large number of phosphonate structures with dioxaphospholane rings, forming a nitrogen-phosphorus flame retardant, which exhibits a good condensed-phase flame retardant effect, significantly improving the flame retardancy of the thermal insulation board and having a higher limiting oxygen index.

[0049] In Comparative Example 1, no polystyrene-based flame retardant was added. The insulation board was easy to burn, with a very low limiting oxygen index, a relatively low compressive strength, and a relatively high thermal conductivity. This was because the compatibility between silica aerogel and polystyrene resin was poor, which had a great impact on the mechanical properties of the insulation board. Moreover, it was difficult for silica aerogel to be evenly dispersed in the polystyrene matrix, resulting in a relatively high thermal conductivity of the board and poor heat insulation performance.

[0050] In Comparative Example 2, an intermediate A was used for the polymerization reaction, and the obtained polystyrene-based flame retardant did not contain a phosphoric acid ester structure with a dioxaphospholane ring, so the flame retardant effect was poor and the insulation board was easy to burn with a relatively low limiting oxygen index. However, this polystyrene-based flame retardant contained carboxyl groups, which could react with the amino groups of silica aerogel during the high-temperature melting process in the extruder, facilitating the improvement of the compatibility of silica aerogel in the polystyrene foamed board and the improvement of the dispersibility. The compressive strength of the board was relatively large and the thermal conductivity was relatively low.

[0051] The silica aerogel in Comparative Example 3 did not contain amino groups and could not react with the carboxyl groups of the polystyrene-based flame retardant, resulting in the inability to graft polystyrene-like molecular chains on the surface of the silica aerogel. The compatibility between the aerogel and polystyrene resin was poor and the dispersibility was not good, leading to a relatively low compressive strength and a relatively high thermal conductivity of the board.

[0052] The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. For those of ordinary skill in the art, without departing from the spirit and scope of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A process for preparing a polystyrene flame retardant thermal insulation board, characterized in that: The preparation process comprises the following steps: Step (1), adding a structural formula The flame retardant intermediate, azobisisobutyronitrile, is heated to the reaction temperature in a nitrogen atmosphere, stirred for reaction, concentrated under reduced pressure, filtered, and washed to obtain a polystyrene-based flame retardant; Step (2), adding 100 parts by weight of polystyrene resin, 8-25 parts by weight of polystyrene resin-based flame retardant, 1-5 parts by weight of amino silica aerogel, 0.6-0.9 parts by weight of foaming agent, 0.5-0.7 parts by weight of antioxidant, and 2.5-4 parts by weight of nucleating agent into a twin-screw extruder for melt extrusion, and then extruding and foaming in a single-screw extruder to obtain a polystyrene flame retardant insulation board.

2. The preparation process of the polystyrene flame retardant thermal insulation board according to claim 1, characterized in that: In the step (1), the mass ratio of the flame retardant intermediate to azobisisobutyronitrile is 1:(0.003-0.004).

3. The preparation process of the polystyrene flame retardant thermal insulation board according to claim 1, characterized in that: In the step (1), the reaction temperature is 75-85° C. and the reaction time is 18-24 h.

4. The preparation process of the polystyrene flame retardant thermal insulation board according to claim 1, characterized in that: In the step (2), the foaming agent includes azodicarbonamide or diisopropyl azodicarboxylate; the nucleating agent includes talcum powder; and the antioxidant includes antioxidant 1010, antioxidant 1076 or antioxidant 168.

5. The preparation process of the polystyrene flame retardant thermal insulation board according to claim 1, characterized in that: In the step (2), the temperature of zones 1-6 of the twin-screw extruder is 180-220°C, and the screw speed is 50-100 r / min; the temperature of zones 1-3 of the single-screw extruder is 180-225°C, and the screw speed is 50-80 r / min.

6. The process for preparing the polystyrene flame retardant thermal insulation board according to claim 1, characterized in that: The preparation process of the amino silica aerogel is as follows: adding tetraethyl orthosilicate to ethanol, stirring and then dropping a hydrochloric acid solution to adjust the pH to 3-3.5, heating to 60-65° C., stirring and reacting for 1.5-2.5 hours, cooling and then adding N,N-dimethylformamide, stirring and then dropping an ethanol solution containing 3-aminopropyltriethoxysilane, stirring and then pouring into a mold, standing and gelling, then pouring the gel into ethanol, heating to 40-50° C., aging for 18-24 hours, taking out the gel, washing, and drying to obtain the amino silica aerogel.

7. The process for preparing the polystyrene flame retardant thermal insulation board according to claim 6, characterized in that: The mass ratio of the tetraethyl orthosilicate to 3-aminopropyltriethoxysilane is 1:(0.7-1.1).

8. The process for preparing the polystyrene flame retardant thermal insulation board according to claim 2, characterized in that: The preparation process of the flame retardant intermediate is as follows: Step S1, adding 5-carboxyl-3-amino-1,2,4-triazole, 4-vinylbenzaldehyde, and glacial acetic acid in a mass ratio of (0.97-1.07):1:(0.76-0.84) to ethanol, heating to 75-80°C, condensing and refluxing for 3-5 hours, cooling and filtering, adding the precipitate to ethanol, adding sodium borohydride, stirring and reacting for 3-4 hours, heating for volatilization, cooling for crystallization, washing, and drying to obtain intermediate A; Step S2, adding intermediate A, 5,5-dimethyl-1,3,2-dioxaphosphoryl chloride and triethylamine in a mass ratio of 1:(1.52-1.81):(0.83-0.91) to dichloromethane, stirring and reacting at 20-30° C. for 12-18 hours, heating for volatilization, cooling for crystallization, washing and drying to obtain a flame retardant intermediate.

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