Low-water-absorption halogen-free flame-retardant irradiation crosslinking PA / PBT (polyamide / polybutylene terephthalate) composite material and preparation method thereof

Abstract

The invention discloses a low-water-absorption halogen-free flame-retardant irradiation crosslinking PA / PBT (polyamide / polybutylene terephthalate) composite material which comprises the following raw material components in parts by weight: 20-60 parts of PA66; 10 to 50 parts of PBT (Polybutylene Terephthalate); 15 to 50 parts of glass fiber; 2-10 parts of a compatilizer; 15 to 30 parts of a halogen-free flame retardant; 0.2 to 1 part of a lubricant; 0.5 to 2.0 parts of a compound stabilizer; and 2-5 parts of a crosslinking auxiliary agent. The raw materials are premixed at a high speed and then extruded and granulated by a twin-screw extruder, and then are sequentially subjected to injection molding, irradiation crosslinking of injection molded parts and the like, and the obtained parts can reach V0-grade flame retardance, have extremely low water absorption and relatively high dimensional stability and can bear instantaneous high-temperature impact of 350 DEG C or above. The material can be widely applied to the field of low-voltage electrical appliances such as capacitor shells, load circuit breaker switches, motor shells, terminal boards, coil frameworks, plugs, circuit connectors and telephone distribution boxes.

Description

Technical Field

[0001] The invention relates to a polymer composite material, in particular to a low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material and a preparation method thereof. Background Art

[0002] Polyamide materials are widely used in the fields of automobiles, machinery, electronics, textiles, chemicals, etc. due to their excellent mechanical properties, heat resistance, wear resistance and electrical insulation.

[0003] Polyamide material has a high water absorption rate, and its saturated water absorption rate can reach more than 3%, which affects the dimensional stability and electrical properties of the material, which is particularly prominent for thin-walled parts, and the mechanical strength is greatly reduced.

[0004] Polybutylene terephthalate not only has low water absorption, but also has high heat resistance, good self-lubricating properties, excellent electrical insulation and dimensional stability. It has excellent comprehensive performance and is widely used in automobiles, electronic appliances, mechanical equipment, textiles and other fields.

[0005] Polymer alloy technology uses compatibilizers to make two different polymers compatible at the physical or chemical level, so that different components can complement each other and obtain good comprehensive performance. Therefore, the problem of high water absorption of nylon can be improved by compounding it with a polymer component with low water absorption.

[0006] The water absorption rate of the obtained material is greatly reduced by compounding PBT with low water absorption rate with PA66. For example, CN201510995544 discloses a novel nylon 6-polybutylene terephthalate flame retardant alloy material and its preparation method. The addition of PBT greatly reduces the water absorption rate of the material.

[0007] Irradiation cross-linking technology refers to the technology of forming active species inside the material through high-energy irradiation, and the active species further induce reaction to achieve macromolecular cross-linking. Through high-energy irradiation, conventional linear polymers are transformed into polymers with three-dimensional spatial network structures, and the mechanical properties, chemical resistance, electrical properties, heat resistance (instantaneous heat resistance) and weather resistance of the product are significantly improved.

[0008] Radiation cross-linking technology can induce interfacial bridging reactions, improve the compatibility between blending components, and significantly improve material properties. Summary of the invention

[0009] The present invention adds a certain amount of PBT resin with low water absorption characteristics to PA66 resin, and achieves V0 flame retardancy by adding a halogen-free flame retardant. At the same time, the interface strength of the PA66 / PBT composite material is improved by radiation cross-linking technology, giving it higher mechanical properties, chemical resistance, electrical properties, heat resistance (instantaneous heat resistance) and weather resistance, and can be widely used in the fields of automobiles, electronic appliances, mechanical equipment, etc.

[0010] The present invention achieves the above-mentioned invention object by the following technical means.

[0011] A low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material and a preparation method thereof, comprising the following raw material components in parts by weight: PA66: 20-60 parts PBT: 10-50 parts Glass fiber 15-50 parts Compatibilizer: 2-10 parts Halogen-free flame retardant: 15-30 parts Heat stabilizer: 0.5-2.0 parts Cross-linking agent: 1-5 parts Lubricant: 0.5-1 part.

[0012] The PA may be one or more of PA66, PA6, PA12, PA56, copolymerized PA66 / 6, etc., including but not limited to the above non-high temperature nylon varieties, preferably PA66, wherein the melt index of PA66 is 5-40g / 10min, 275°C / 2.16 kg; preferably 10-25g / 10min.

[0013] The intrinsic viscosity of the polybutylene terephthalate is 0.8-1.5 dL / g, and a higher viscosity is preferred.

[0014] The glass fiber is alkali-free glass fiber short fiber, the surface of which is treated with a coupling agent, and the length of the short fiber is preferably 3-12 mm.

[0015] The compatibilizer may be one or more of epoxy resin CYD-011, epoxy resin E-54, and ethylene-acrylic acid-glycidyl methacrylate E-MA-GMA, preferably E-MA-GMA.

[0016] The halogen-free flame retardant may be one or more of a phosphorus-based flame retardant, an inorganic flame retardant, a nitrogen-based flame retardant, a phosphorus-nitrogen-based flame retardant, etc., preferably diethyl aluminum hypophosphite (ADP).

[0017] The heat stabilizer may be one or more of a hindered phenol antioxidant or a phosphite antioxidant. The hindered phenol antioxidant may be antioxidants 1010 and 1098, and the phosphite antioxidant may be antioxidants 168, 608, 626, 9228, and the like.

[0018] The cross-linking aid may be one or more of triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), trimethylallyl isocyanurate (TMAIC), trimethylolpropane trimethacrylate (TMPTMA), preferably trimethylolpropane trimethacrylate (TMPTMA).

[0019] The lubricant can be one or more of silicone lubricant, silicone oil, zinc stearate, sodium stearate, calcium stearate, pentaerythritol stearate, ethylene bisstearamide, polyethylene wax, oxidized polyethylene wax, ethylene-acrylic acid copolymer, and montan acid wax.

[0020] The material is melt extruded and granulated by a twin-screw extruder, with a screw speed of 250-450 rpm / min, a screw length-diameter ratio of 50:1, and an extruder temperature of 170-280°C. The resin and powder are melt-blended and then extruded and granulated. The cross-linking aid can be added to the main feed or side feed of the extruder screw, or in the form of external mixing of the cross-linking aid masterbatch.

[0021] The cross-linking method uses high-energy irradiation cross-linking, the irradiation rays are electron beams, gamma rays, and X-rays, and the irradiation dose is 50-300 kGy.

[0022] This product can be added with different types of color powder to obtain specific colors according to customer needs.

[0023] Compared with the prior art, the present invention has the following innovative advantages: By adding low-water-absorption PBT to PA66, the overall water absorption rate of the material is greatly reduced, overcoming the problems of high water absorption rate, unstable size and performance of single PA66 material.

[0024] The innovative use of radiation cross-linking technology, combined with radiation technology and compatibilizers with epoxy groups, can greatly improve the compatibility between the blending components, reduce the effect of phase separation of the blending system on water absorption, and at the same time give the material good mechanical properties.

[0025] This product innovatively uses radiation cross-linking technology. By inducing resin cross-linking, the material has the characteristics of being difficult to melt at high temperatures and difficult to dissolve in solvents. It can withstand instantaneous high temperatures of up to 350°C and has good applicability in terms of arc resistance. At the same time, cross-linking reduces the water absorption rate of the material, improves the dimensional stability of the material, and greatly improves the overall performance of the material.

[0026] At the same time, the present invention provides a new type of low water absorption and high strength halogen-free flame-retardant nylon material composite material, which provides an innovative solution for the application of nylon. The composite material can be used in low-voltage electrical appliances such as container shells, load break switches, motor shells, terminal boards, coil skeletons, plugs, circuit connectors, and telephone distribution boxes. DETAILED DESCRIPTION

[0027] The following is a detailed description of embodiments of the invention. It is necessary to state that the following embodiments cannot be understood as limiting the scope of protection of the invention. If technicians in this field make some non-essential improvements and adjustments to the invention based on the above content, they still fall within the scope of protection of the invention.

[0028] The extrusion granulation implementation process includes the following processes: Before extrusion treatment, PA66 was dried in an oven at 110°C for 4 h.

[0029] After drying, weigh each component material according to the ratio in Table 1 and add it into a high-speed mixer and stir evenly.

[0030] The specific proportions of Examples 1-5 and Comparative Examples 1-2 are shown in Table 1 below, with the raw materials being expressed in mass percentage: Raw materials (mass fraction) Example 1 Example 2 Example 3 Example 4 Example 5 Comparison sample 1 Comparison sample 2 PA66 35 35 35 35 35 35 35 PBT 15 15 15 15 15 15 15 Fiberglass 30 30 30 30 30 30 30 Compatibilizer 1 5 Compatibilizer 2 5 Compatibilizer 3 5 5 5 Maleic Anhydride Grafted POE 5 5 Halogen-free flame retardant 17 17 17 17 20 20 23 Heat Stabilizer 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Crosslinking agent 1 3 3 3 3 3 Crosslinking agent 2 3 3 Lubricants 0.2 0.2 0.2 0.2 0.2 0.2 0.2 The compatibilizers 1, 2, and 3 in the table are epoxy resin CYD-011, epoxy resin E-54, and ethylene-acrylic acid-methyl glycidyl methacrylate E-MA-GMA, respectively.

[0031] The crosslinking aids 1 and 2 are trimethylolpropane trimethacrylate (TMPTMA) and triallyl isocyanurate (TAIC), respectively.

[0032] The halogen-free flame retardant in the table is diethyl aluminum hypophosphite (ADP); the glass staple fiber used is 301hp; the heat stabilizer is 1010 / 9228 compound; the lubricant is calcium stearate; and the crosslinking aid is triallyl isocyanurate (TAIC).

[0033] After the above components are mixed evenly, they are mixed and extruded through a twin-screw extruder with an extrusion temperature of 170-290° C. and a main engine speed of 350-380 rpm / min.

[0034] After extrusion, it is water cooled and pelletized.

[0035] After granulation, low-temperature drying and injection molding are carried out, and the injection molding temperature is 240-280℃.

[0036] The injection molded parts are irradiated using a 10 MeV electron accelerator to ensure uniform irradiation. The irradiation dose is between 25-300 kGy, preferably 150 kGy.

[0037] According to the relevant national standards, various performance tests were carried out on the materials, mainly focusing on the performance before and after irradiation (0 kGy and 150 kGy). The specific experimental results are shown in Table 2 below.

[0038] Performance Indicators Test Standards Test Unit Example 1 Example 1 Example 2 Example 2 Example 3 Example 3 Example 4 Example 4 Example 5 Example 5 Comparison sample 1 Comparison sample 1 Comparison sample 2 Comparison sample 2 Radiation dose - k 0 150 0 150 0 150 0 150 0 150 0 150 0 150 Tensile Strength GB / T1040.2-2006 Mpa 129 135 127 131 128 143 121 135 117 132 113 129 110 125 Bending Strength GB / T9341.1-2008 Mpa 204 217 205 218 189 233 170 211 172 214 174 193 181 200 Flexural modulus GB / T9341.1-2008 Mpa 8086 8495 8009 8213 7811 8918 7711 8315 7533 8191 7186 7350 7210 7433 Flame retardant grade GB / T2408-2008 / V1 V0 V1 V0 V0 V0 V1 V1 V1 V0 V1 V1 V0 V0 Hot Needle Test 350℃*60s um X <15 X <10 X <5 X <20 X <18 X <25 X <25 Water absorption GB / T1034-2008 % 0.81 0.75 0.62 0.41 0.21 0.17 0.33 0.28 0.38 0.31 2.5 1.8 2.5 1.7 Note: The hot needle test follows the industry's internal common method and is carried out using the company's internal standards. Its essence is a needle-type electric soldering iron, and the needle tip can quickly rise to the set temperature. The parameters of our company's electric soldering iron are as follows: the needle tip is a cylinder with a diameter of 2 mm, the temperature is calibrated, the load weight is 1.05 kg, the total pressure is about 3.28 MPa, and it can rise to the specified temperature within 1-2 minutes after power is turned on and basically reach a stable state. When the reinforced material is well irradiated and cross-linked, the material has the characteristics of not melting at high temperature and not dissolving in solvents. When encountering a needle tip with a temperature exceeding the melting point of the material, the material still behaves as a hard rubber state and can withstand a certain pressure; when the material cross-linking degree is poor or not irradiated and cross-linked, the material as a whole has the characteristics of a thermoplastic material. When encountering an electric soldering iron with a needle tip temperature exceeding the melting point of the material, the surface of the material quickly melts within 1-3 s, and is penetrated by the electric soldering iron needle tip until it is pierced. In Table 2, X represents the immediate melting sinking when the hot needle touches it, and the number represents the melting depth. For PA materials, the commonly used experimental temperature is 350℃ or 400℃.

[0039] Based on the above performance, it can be seen that Example 3 is a composite material with extremely low water absorption, high mechanical strength, excellent halogen-free flame retardant properties, and extremely high instantaneous high temperature resistance, which can overcome the defect of high water absorption of pure PA material and can be used to replace pure PA66 material in low-voltage electrical appliances, automobiles, machinery and other fields.

Claims

1. A low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material, comprising the following raw material components in parts by weight: PA66: 20-60 parts PBT: 10-50 parts Glass fiber 15-50 parts Compatibilizer: 2-10 parts Halogen-free flame retardant: 15-30 parts Heat stabilizer: 0.5-2.0 parts Cross-linking agent: 1-5 parts Lubricant: 0.5-1 part.

2. According to claim 1, a low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material, characterized in that: The PA resin may be one or more of PA66, PA6, PA12, PA56, copolymerized PA66 / 6, etc.

3. The low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to claim 1, characterized in that: The intrinsic viscosity of the polybutylene terephthalate is 0.8-1.5 dL / g.

4. The low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to claim 1, characterized in that: The glass fiber is alkali-free glass fiber short fiber, and the surface of the glass fiber is treated with a coupling agent.

5. The low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to claim 1, characterized in that: The compatibilizer may be one or more of epoxy resin CYD-011, epoxy resin E-54, and ethylene-acrylic acid-glycidyl methacrylate E-MA-GMA.

6. The low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to claim 1, characterized in that: The halogen-free flame retardant may be one or more of a phosphorus-based flame retardant, an inorganic flame retardant, a nitrogen-based flame retardant, a phosphorus-nitrogen-based flame retardant, and the like.

7. The low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to claim 1, characterized in that: The heat stabilizer is an antioxidant, which can be one or more of a hindered phenol antioxidant and a phosphite antioxidant, wherein the hindered phenol antioxidant can be antioxidants 1010 and 1098, and the phosphite antioxidant can be antioxidants 168, 626, and 9228. The lubricant can be one or more of a silicone lubricant, silicone oil, zinc stearate, sodium stearate, calcium stearate, pentaerythritol stearate, ethylene bisstearamide, polyethylene wax, oxidized polyethylene wax, ethylene-acrylic acid copolymer, and montan acid wax.

8. The low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to claim 1, characterized in that: The cross-linking auxiliary agent is one or more of triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), trimethylallyl isocyanurate (TMAIC), and trimethylolpropane trimethacrylate (TMPTMA).

9. A method for preparing a low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to any one of claims 1 to 8, comprising the steps of: after surface treatment of the filler, adding each component in a high-speed premixer in proportion and mixing, then extruding and granulating with a twin-screw extruder, the screw speed is 250-400 rpm / min, the screw aspect ratio is recommended to be 50:1, the extruder temperature is between 170-290°C, and after granulation and drying, further injection molding, wherein the cross-linking aid can be added by main feeding or side feeding of the extruder, or by external mixing of masterbatch, and the composite material can be obtained by cross-linking with high-energy rays.

10. The method for preparing a low water absorption halogen-free flame retardant radiation cross-linked PA / PBT composite material according to claim 9, characterized in that: The cross-linking method is high-energy ray irradiation cross-linking, which can be electron beam irradiation, gamma ray irradiation, or X-ray irradiation, with an irradiation dose of 50-300 kGy; the obtained injection molded part is irradiated to obtain the above composite material.