Preparation method of high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material

Abstract

The invention discloses a preparation method of a high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material. The preparation method sequentially comprises the following steps: S1, preparing the following raw materials in parts by mass: 50-80 parts of syndiotactic polystyrene, 10-30 parts of potassium titanate whiskers, 3-5 parts of a core-shell toughening agent, 2-10 parts of a phosphazene flame retardant and 1-10 parts of a processing aid; s2, mixing the syndiotactic polystyrene, the core-shell toughening agent, the phosphazene flame retardant and the processing aid in proportion in a rotary mixer, feeding from a main feed opening of a twin-screw extruder, feeding the potassium titanate whiskers from a side feed opening of the extruder through a feeder, and performing melt mixing, extrusion and granulation; s3, the rotation speed of the rotary mixer in the step S2 is 60-120 rpm, and the mixing time is 5-10 min. The high-efficiency halogen-free phosphazene flame retardant is adopted, is environment-friendly, and has the advantages of small filling amount and small influence on the physical properties of the material. And the flame retardant has a light color and does not influence material coloring relative to red phosphorus.

Description

Technical Field

[0001] The invention relates to the field of engineering plastic composite materials, and in particular to a method for preparing a high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material. Background Art

[0002] Syndiotactic polystyrene (SPS) is a crystalline polymer obtained by catalytic polymerization of styrene monomer using a metallocene catalyst. Unlike general-purpose polystyrene, syndiotactic polystyrene is obtained by coordination polymerization using a special catalytic system with syndiotactic stereoselectivity. The molecular chain configuration is syndiotactic, and the side groups (benzene rings) in the structural unit are arranged alternately on both sides of the macromolecular chain. Since syndiotactic polystyrene has high stereoregularity (syndiotactic structure>99%), it has strong crystallization ability and a melting point of about 270°C. It not only inherits the excellent properties of general-purpose polystyrene such as low density, excellent electrical properties, good hydrolysis stability, and low price; but also syndiotactic polystyrene is a semi-crystalline polymer with excellent mechanical properties as well as heat resistance, solvent resistance and dimensional stability, and the crystallization rate is much faster than that of isotactic polystyrene, so it is suitable for injection molding. Because its relative density is 20% to 30% lower than that of engineering plastics such as LCP and PPS, and its own material price is low, the cost advantage is obvious, so it has great application prospects in related electronic and electrical fields.

[0003] However, the SPS material itself is too brittle, has low impact strength, and the unmodified material has a flame retardant grade of HB, which greatly limits its application in electrical fields that require flame retardancy, such as PCB connectors, ECU housings, etc.

[0004] At present, the existing technology generally adopts the method of composite filling and modification of elastomer and glass fiber, and utilizes the concentrated effect of elastomer on impact stress to prevent crack propagation and improve the impact resistance. However, the addition of elasticity will greatly reduce the fluidity of the matrix, which is not conducive to the molding processability of the material, and generally has poor compatibility with the matrix and is prone to poor dispersion. At the same time, glass fiber plays a role in skeleton reinforcement in the resin matrix, which can further improve the impact resistance of the matrix. However, due to the large fiber size of the glass fiber itself and the general ability to bind to the organic interface, it is easy to produce floating fibers that affect the appearance of the product. The flame retardant modification of SPS materials generally adopts halogen-containing flame retardants, such as decabromodiphenylethane, brominated polystyrene, etc. However, this type of halogen-containing flame retardant has great environmental hazards and is added in large quantities. It is gradually being eliminated by the market. Red phosphorus halogen-free flame retardant is also used, but its appearance application is limited by the color of red phosphorus. The inorganic flame retardant method of magnesium hydroxide and aluminum hydroxide is adopted. Due to the large amount of such flame retardants added, the physical properties of the material are greatly reduced. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material, wherein a core-shell toughening agent is used to fill and modify SPS, wherein the shell layer is polystyrene and the core layer is a polyacrylate polymer. Since the shell layer has excellent compatibility with the matrix SPS resin, the dispersion effect is better than that of the traditional toughening agent, and the polyacrylate elastomer of the core layer plays a toughening role. The use of an efficient halogen-free phosphazene flame retardant is environmentally friendly, has a small filling amount, and has little effect on the physical properties of the material. Moreover, the flame retardant itself is lighter in color, and will not affect the coloring of the material relative to red phosphorus.

[0006] To achieve the above object, the present invention provides the following technical solutions.

[0007] The present application discloses a method for preparing a high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material, which comprises the following steps in sequence:

[0008] S1 prepare the following raw materials by mass: 50-80 parts of syndiotactic polystyrene, 10-30 parts of potassium titanate whiskers, 3-5 parts of core-shell toughening agent, 2-10 parts of phosphazene flame retardant, and 1-10 parts of processing aid;

[0009] S2: after mixing the syndiotactic polystyrene, core-shell toughening agent, phosphazene flame retardant and processing aid in a rotary mixer in proportion, feeding them from the main feeding port of a twin-screw extruder, and feeding the potassium titanate whisker from the side feeding port of the extruder through a feeder, to perform melt mixing, extrusion and granulation;

[0010] In step S3, the rotary mixer in step S2 has a rotation speed of 60-120 rpm, a mixing time of 5-10 min, an output of the twin-screw extruder of 100-200 Kg / h, a rotation speed of 200-400 rpm, a barrel temperature of 280±20°C, a head temperature of 275±10°C, and a vacuum section extraction pressure of -0.08±0.02 MPa.

[0011] Preferably, in the preparation method of the above-mentioned high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material, the syndiotactic polystyrene notched impact strength is greater than 10KJ / m 2 .

[0012] Preferably, in the method for preparing the above-mentioned high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material, the shell layer of the core-shell toughening agent is polystyrene, and the core layer is polyethyl acrylate.

[0013] Preferably, in the method for preparing the above-mentioned high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material, the phosphazene flame retardant is hexaphenoxy cyclotriphosphazene produced by Otsuka Chemical of Japan, with the brand name SPB-100.

[0014] Preferably, in the method for preparing the above-mentioned high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material, the processing aid includes a mixture of polyethylene wax, hindered phenol antioxidant and phosphite antioxidant in a proportion of 4:2:1 by mass.

[0015] The present invention adopts a core-shell toughening agent to fill and modify SPS, wherein the shell layer is polystyrene and the core layer is a polyacrylate polymer. Since the shell layer has excellent compatibility with the matrix SPS resin, the dispersion effect is better than that of the traditional toughening agent, and the polyacrylate elastomer in the core layer plays a toughening role. The use of efficient halogen-free phosphazene flame retardant is environmentally friendly, has a small filling amount, and has little effect on the physical properties of the material. In addition, the flame retardant itself is lighter in color and will not affect the coloring of the material compared to red phosphorus. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention are described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Example 1: After syndiotactic polystyrene (69 parts), toughening agent (5 parts), flame retardant (5 parts), and processing aid (1 part) are mixed in a rotary mixer in proportion, they are fed from the main feed port of a twin-screw extruder, and potassium titanate whisker TISMO D (20 parts) is fed from the side feed port of the extruder via a feeder, and melt-mixed extrusion granulation is performed. The rotary mixer used has a rotation speed of 100 rpm and a mixing time of 10 min. The twin-screw extruder has an output of 150 kg / h, a rotation speed of 200 rpm, a barrel temperature of 280°C, a die temperature of 370°C, and a vacuum section extraction pressure of -0.08 MPa.

[0018] Example 2: After syndiotactic polystyrene (61 parts) and toughening agent (3 parts) were mixed in a rotary mixer according to the ratio of flame retardant (5 parts) and processing aid (1 part), they were fed from the main feed port of a twin-screw extruder, and potassium titanate whisker TISMO D (30 parts) was fed from the side feed port of the extruder via a feeder, and melt-mixed extrusion granulation was performed. The rotary mixer used had a rotation speed of 100 rpm and a mixing time of 10 min. The twin-screw extruder had an output of 120 kg / h, a rotation speed of 180 rpm, a barrel temperature of 290°C, a head temperature of 280°C, and a vacuum section extraction pressure of -0.08 MPa.

[0019] The properties of the composite material prepared according to the present invention are as follows: the strength and flame retardancy are higher than those of the typical comparative example (SPS / 20% GF / 5% SEBS / 15% DBDPE / 5% Sb2O3)

[0020] Example 1 Example 2 Comparative Example Tensile strength MPa 100 120 90 Bending strength MPa 150 170 140 <![CDATA[Notched impact strength KJ / m 2 > 12.0 10.0 8.0 UL94 flame retardant grade 0.8mm V-0 V-0 V-1

[0021] This implementation mode is only an exemplary description of this patent and does not limit its protection scope. Personnel in this field may also make partial changes to it. As long as it does not exceed the spirit of this patent, it shall be regarded as an equivalent replacement of this patent and shall be within the protection scope of this patent.

Claims

1. A method for preparing a high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material, characterized in that: The steps are as follows: S1 prepare the following raw materials by mass: 50-80 parts of syndiotactic polystyrene, 10-30 parts of potassium titanate whiskers, 3-5 parts of core-shell toughening agent, 2-10 parts of phosphazene flame retardant, and 1-10 parts of processing aid; S2: after mixing the syndiotactic polystyrene, core-shell toughening agent, phosphazene flame retardant and processing aid in a rotary mixer in proportion, feeding them from the main feeding port of a twin-screw extruder, and feeding the potassium titanate whisker from the side feeding port of the extruder through a feeder, to perform melt mixing, extrusion and granulation; In step S3, the rotary mixer in step S2 has a rotation speed of 60-120 rpm, a mixing time of 5-10 min, an output of the twin-screw extruder of 100-200 Kg / h, a rotation speed of 200-400 rpm, a barrel temperature of 280±20°C, a head temperature of 275±10°C, and a vacuum section extraction pressure of -0.08±0.02 MPa.

2. The method for preparing the high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material according to claim 1, characterized in that: The notched impact strength of the syndiotactic polystyrene is greater than 10 KJ / m 2 .

3. The method for preparing the high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material according to claim 1, characterized in that: The shell layer of the core-shell toughening agent is polystyrene, and the core layer is polyethyl acrylate.

4. The method for preparing the high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material according to claim 1, characterized in that: The phosphazene flame retardant is hexaphenoxy cyclotriphosphazene produced by Otsuka Chemical of Japan, with the brand name SPB-100.

5. The method for preparing the high-toughness halogen-free flame-retardant syndiotactic polystyrene composite material according to claim 1, characterized in that: The processing aid comprises a mixture of polyethylene wax, a hindered phenol antioxidant and a phosphite antioxidant in a proportion of 4:2:1 by mass.