Halogen-free flame-retardant polystyrene foamed sheet and preparation method thereof

Abstract

The invention discloses a halogen-free flame-retardant polystyrene foamed sheet and a preparation method thereof. The halogen-free flame-retardant polystyrene foamed sheet is prepared from the following raw materials in parts by weight: 100 parts of polystyrene (PS), 10-60 parts of calcium carbonate / talcum powder (filler), 5-15 parts of a foaming agent, 30-70 parts of a phosphorus / nitrogen flame retardant, 1-2 parts of a dispersing agent, 1-2 parts of a lubricating agent and 0.1-1.2 parts of an antioxidant. The halogen-free flame-retardant polystyrene foamed sheet prepared by the invention has the characteristics of good halogen-free flame-retardant performance, thermal insulation performance, oxidation resistance, easiness in processing and molding and the like, and is a halogen-free flame-retardant polystyrene foamed sheet with excellent comprehensive performance.

Description

Technical Field

[0001] The present invention relates to a foamed sheet and a preparation method thereof, and particularly to a halogen-free flame-retardant polystyrene foamed sheet and a preparation method thereof, belonging to the field of foamed sheet materials. Background Art

[0002] As a core material in the fields of building insulation, cold chain packaging, electronic buffering, etc., the market scale of polystyrene (PS) foamed sheets has been continuously expanding. Traditional PS foamed sheets mainly rely on halogen-containing flame retardants (such as hexabromocyclododecane) to achieve flame retardancy. However, with the tightening of environmental protection policies such as the Montreal Protocol and the EU REACH Regulation, the halogen-containing system faces elimination due to problems such as the release of dioxins and corrosive gases during combustion. In addition, pure PS foamed sheets have defects such as high flammability (oxygen index is only 18-19%), high brittleness, and poor impact resistance, and it is difficult to meet the requirements of modern engineering for safety and durability. Inorganic flame retardants such as magnesium hydroxide (MDH) and aluminum hydroxide (ATH) have the dual functions of flame retardancy and smoke suppression. However, MDH and ATH flame retardants require a very high addition amount, which not only increases the melt viscosity of the mixture and makes processing difficult. Synergistic use of phosphorus / nitrogen flame retardants can not only meet the requirements of flame retardancy but also effectively maintain the processing performance of the material, which is an important way to solve the above problems. Summary of the Invention

[0003] The purpose of the present invention is to provide a halogen-free flame-retardant polystyrene foamed sheet and a preparation method thereof to solve the problems existing in the prior art. To achieve the above invention purpose, the present invention adopts the following technical solutions:

[0004] A halogen-free flame-retardant polystyrene foamed sheet is prepared from the following raw materials in parts by weight: 100 parts of polystyrene (PS), 10-60 parts of calcium carbonate / talc (filler), 5-15 parts of foaming agent, 30-70 parts of phosphorus / nitrogen flame retardant, 1-2 parts of dispersant, 1-2 parts of lubricant, and 0.1-1.2 parts of antioxidant.

[0005] As a further optimized scheme of the halogen-free flame-retardant polystyrene foamed sheet provided by the present invention, the polystyrene (PS) is a block copolymer.

[0006] As a further optimized scheme of the halogen-free flame-retardant polystyrene foamed sheet provided by the present invention, the calcium carbonate / talc is an inorganic filler.

[0007] As a further optimized scheme of the halogen-free flame-retardant polystyrene foamed sheet provided by the present invention, the foaming agent is azodicarbonamide, and its appearance is orange-yellow powder.

[0008] As a further optimized solution of the halogen-free flame-retardant polystyrene foam board provided by the present invention, the dispersant is polyvinyl alcohol (PVA).

[0009] As a further optimized solution of the halogen-free flame-retardant polystyrene foam board provided by the present invention, the phosphorus / nitrogen flame retardant is melamine MCA and melamine polyphosphate MPP.

[0010] As a further optimized solution of the halogen-free flame-retardant polystyrene foam board provided by the present invention, the antioxidant is composed of a phenolic antioxidant and a phosphite antioxidant, and the mass ratio of the two added is 1:1.

[0011] Preferably, the phosphite antioxidant is antioxidant 168, which appears as a white crystalline powder, with the full name of tris[2,4-di-tert-butylphenyl] phosphite, and the melting point is 183-187°C.

[0012] Preferably, the phenolic antioxidant is antioxidant 300, with a melting point of 161-165°C, the full name of 4,4'-thiobis(6-tert-butyl-m-cresol), and it appears as a white or light yellow powder.

[0013] In order to better achieve the above-mentioned invention purpose, the present invention also provides a preparation method of a halogen-free flame-retardant polystyrene foam board, and the preparation method is as follows:

[0014] In the first step, calcium carbonate / talc powder (10-60 parts) and 0.5%-1% stearic acid (or silane coupling agent) are mixed in a high-speed mixer at 800-1200 r / min for 10-15 minutes. The phenolic antioxidant (such as 1010) and the phosphite antioxidant (such as 168) are mixed in a ratio of 1:1, dissolved in ethanol and then sprayed on the surface of the PS resin, and dried for standby. The pretreated PS resin (100 parts), phosphorus / nitrogen flame retardant (a total of 30-70 parts of melamine MCA + MPP), dispersant PVA (1-2 parts), lubricant (a total of 1-2 parts of stearate + polyethylene wax), and nano-silica abrasion-resistant agent (0.1-1.2 parts) are put into a high-speed mixer and mixed at 300-500 r / min for 5-8 minutes to form a uniform premix. Then, melt blending is carried out at 180-220°C through a twin-screw extruder, and the screw speed is 200-300 r / min. The azodicarbonamide foaming agent (5-15 parts) is added to the middle side feeding port of the extruder, and high shear force is used to ensure its uniform dispersion in the melt;

[0015] In the second step, control the head pressure of the extruder at 8 - 12 MPa and the temperature at 190 - 210 °C to decompose azodicarbonamide to generate N2 gas and form pores. By adjusting the screw speed and die size, achieve a foaming ratio of 15 - 30 times. The extrudate is rapidly cooled to below 50 °C by a cold water bath or an air cooling device to quickly fix the pore structure, and a halogen-free flame-retardant polystyrene foam board is prepared.

[0016] Compared with the existing technologies, the beneficial effects of the present invention are as follows: The halogen-free flame-retardant polystyrene foam board prepared by the present invention has good halogen-free flame-retardant performance, heat insulation performance, antioxidant property and easy processing and forming characteristics, and is a halogen-free flame-retardant polystyrene foam board with excellent comprehensive performance. Specific Embodiments

[0017] A halogen-free flame-retardant polystyrene foam board provided by the present invention is prepared from the following raw materials in parts by weight: 100 parts of polystyrene (PS), 10 - 60 parts of calcium carbonate / talc powder (filler), 5 - 15 parts of foaming agent, 30 - 70 parts of phosphorus / nitrogen flame retardant, 1 - 2 parts of dispersant, 1 - 2 parts of lubricant, 0.1 - 1.2 parts of antioxidant.

[0018] The polystyrene (PS) adopted in the present invention is a block copolymer.

[0019] Specifically, the polystyrene (PS) is produced by BASF of Germany, and its appearance is granular. It has good toughness and processing performance, and the melt flow rate is 10 - 20 g / 10 min (200 °C, 5 kg load).

[0020] The calcium carbonate / talc powder adopted in the present invention is an inorganic filler.

[0021] Specifically, the calcium carbonate is heavy calcium carbonate produced by a certain mine in Hezhou City, Guangxi Zhuang Autonomous Region, with a particle size of 1250 mesh and a whiteness of ≥95%; the talc powder is produced by a certain mine in Haicheng, Liaoning, with a particle size of 2000 mesh and a whiteness of ≥90%.

[0022] The foaming agent adopted in the present invention is azodicarbonamide.

[0023] Specifically, the azodicarbonamide is produced by a certain chemical enterprise in Shandong, and its appearance is orange-yellow powder. The decomposition temperature is 190 - 210 °C, and the gas generation amount is 200 - 220 ml / g.

[0024] The dispersant adopted in the present invention is polyvinyl alcohol (PVA).

[0025] Specifically, the polyvinyl alcohol is produced by Anhui Wanwei High-Tech Materials Co., Ltd., with a degree of polymerization of 1700, a degree of alcoholysis of 99%, and an appearance of white powder.

[0026] The phosphorus / nitrogen flame retardants used in the present invention are melamine MCA and melamine polyphosphate MPP.

[0027] Specifically, the addition ratio of MCA and MPP is 1:2.

[0028] The lubricants used in the present invention are stearic acid esters and polyethylene wax.

[0029] Specifically, the stearic acid ester is butyl stearate, produced by a certain chemical company in Guangdong; the polyethylene wax is produced by a certain enterprise in Shanghai, with a melting point of 100 - 110°C and a density of 0.92 - 0.94 g / cm 3 . The addition ratio of the two is 1:1.

[0030] The antioxidant used in the present invention is composed of a phenolic antioxidant and a phosphite antioxidant, and the mass ratio of the two added is 1:1.

[0031] Specifically, the phosphite antioxidant is antioxidant 168, which appears as a white crystalline powder, with the full name of tris[2,4 - di - tert - butylphenyl] phosphite, and a melting point of 183 - 187°C.

[0032] Specifically, the phenolic antioxidant is antioxidant 300, with a melting point of 161 - 165°C, the full name of 4,4'-thiobis(6 - tert - butyl - m - cresol), and appears as a white or light yellow powder.

[0033] In order to better achieve the above - mentioned invention purpose, the present invention also provides a preparation method of a halogen - free flame - retardant polystyrene foam board, and the preparation method is as follows:

[0034] First step, mix calcium carbonate / talc powder (10 - 60 parts) with 0.5% - 1% stearic acid (or silane coupling agent) in a high - speed mixer at 800 - 1200 r / min for 10 - 15 minutes. Mix the phenolic antioxidant (such as 1010) and the phosphite antioxidant (such as 168) in a ratio of 1:1, dissolve them in ethanol and then spray them on the surface of PS resin, and dry for standby. Put the pretreated PS resin (100 parts), phosphorus / nitrogen flame retardant (a total of 30 - 70 parts of melamine MCA + MPP), dispersant PVA (1 - 2 parts), lubricant (a total of 1 - 2 parts of stearic acid ester + polyethylene wax), and nano - silica abrasion - resistant agent (0.1 - 1.2 parts) into a high - speed mixer, mix at 300 - 500 r / min for 5 - 8 minutes to form a uniform premix. Then, melt - blend through a twin - screw extruder at 180 - 220°C, with a screw speed of 200 - 300 r / min. Add azodicarbonamide blowing agent (5 - 15 parts) at the middle side - feeding port of the extruder, and use high - shear force to ensure its uniform dispersion in the melt;

[0035] In the second step, control the head pressure of the extruder at 8 - 12 MPa and the temperature at 190 - 210 °C to decompose azodicarbonamide to generate N2 gas and form foam cells. By adjusting the screw speed and die size, achieve a foaming ratio of 15 - 30 times. Quench the extrudate to below 50 °C through a cold water bath or an air cooling device to quickly fix the foam cell structure, and obtain a halogen-free flame-retardant polystyrene foam board.

[0036] The following examples further illustrate the content of the present invention, but should not be construed as a limitation thereto. Without departing from the spirit and essence of the present invention, any modification or replacement made to the methods, steps or conditions of the present invention shall fall within the scope of the present invention. The experimental methods without specific conditions noted in the examples and the reagents not described are all in accordance with the conventional conditions in the art.

[0037] Example 1:

[0038] PS: 100 parts

[0039] Calcium carbonate / talc: 30 parts

[0040] Blowing agent: 10 parts

[0041] MCA: 15 parts

[0042] MPP: 30 parts

[0043] Dispersant: 1 part

[0044] Antioxidant 300: 0.5 part

[0045] Antioxidant 168: 0.5 part

[0046] Silica: 1.5 parts

[0047] Example 2:

[0048] PS: 100 parts

[0049] Calcium carbonate / talc: 40 parts

[0050] Blowing agent: 10 parts

[0051] MCA: 20 parts

[0052] MPP: 40 parts

[0053] Dispersant: 1.5 parts

[0054] Antioxidant 300: 0.5 part

[0055] Antioxidant 168: 0.5 part

[0056] Lubricant: 1.5 parts

[0057] Example 3:

[0058] PS: 100 parts

[0059] Calcium carbonate / talc powder: 50 parts, blowing agent: 15 parts

[0060] MCA: 20 parts

[0061] MPP: 40 parts

[0062] Dispersant: 1.5 parts

[0063] Antioxidant 300: 0.5 part, Antioxidant 168: 0.5 part

[0064] Lubricant: 2 parts.

Claims

1. A halogen-free flame-retardant polystyrene foam sheet, characterized in that: The invention is prepared from the following raw materials in parts by weight: 100 parts of polystyrene (PS), 10 to 60 parts of calcium carbonate / talcum powder (filler), 5 to 15 parts of foaming agent, 30 to 70 parts of phosphorus / nitrogen flame retardant, 1 to 2 parts of dispersant, 1 to 2 parts of lubricant and 0.1 to 1.2 parts of antioxidant.

2. The halogen-free flame-retardant polystyrene foam sheet according to claim 1, characterized in that: The polystyrene (PS) is a block copolymer.

3. The halogen-free flame-retardant polystyrene foam sheet according to claim 1, characterized in that: The calcium carbonate / talcum powder is an inorganic filler.

4. The halogen-free flame-retardant polystyrene foam sheet according to claim 1, characterized in that: The foaming agent is azodicarbonamide, which is in the form of orange powder.

5. The halogen-free flame-retardant polystyrene foam sheet according to claim 1, characterized in that: The phosphorus / nitrogen flame retardant is melamine MCA and melamine polyphosphate MPP.

6. The halogen-free flame-retardant polystyrene foam sheet according to claim 1, characterized in that: The dispersant is polyvinyl alcohol (PVA).

7. The halogen-free flame-retardant polystyrene foam sheet according to claim 1, characterized in that: The lubricant is stearate and polyethylene wax.

8. The halogen-free flame-retardant polystyrene foam sheet according to claim 1, characterized in that: The antioxidant is composed of a phenolic antioxidant and a phosphite antioxidant, and the mass ratio of the two is 1:1; the wear-resistant agent is nano silicon dioxide.

9. A method for preparing a halogen-free flame-retardant polystyrene foam sheet according to any one of claims 1 to 8, characterized in that: The preparation method is as follows: In the first step, calcium carbonate / talcum powder (10-60 parts) and 0.5%-1% stearic acid (or silane coupling agent) are mixed in a high-speed mixer at 800-1200r / min for 10-15 minutes, phenolic antioxidant (such as 1010) and phosphite antioxidant (such as 168) are mixed in a 1:1 ratio, dissolved in ethanol and sprayed on the surface of PS resin, dried and set aside, pretreated PS resin (100 parts), phosphorus / nitrogen flame retardant (melamine MCA+MPP 30-70 parts in total), dispersant PVA (1-2 parts), lubricant (stearate + polyethylene wax 1-2 parts in total), nano-silica wear agent (0.1-1.2 parts) are put into a high-speed mixer at 300~~500r / min. Mix for 5 to 8 minutes to form a uniform premix, then melt blend at 180 to 220°C through a twin-screw extruder with a screw speed of 200 to 300 r / min; add azodicarbonamide foaming agent (5 to 15 parts) at the side feed port in the middle of the extruder, and use high shear force to ensure its uniform dispersion in the melt; The second step is to control the extruder head pressure at 8-12 MPa and the temperature at 190-210°C to decompose azodicarbonamide to produce N2 gas and form bubbles. By adjusting the screw speed and the die size, a foaming ratio of 15 to 30 times is achieved. The extrudate is quenched to below 50°C in a cold water bath or air cooling device to quickly fix the bubble structure and obtain a halogen-free flame-retardant polystyrene foam sheet.