Flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulating property and preparation method of flame-retardant reinforced PPE composite material

Abstract

The invention relates to a hydrolysis-resistant flame-retardant reinforced PPE composite material with excellent electrical insulating property and a preparation method thereof, and the hydrolysis-resistant flame-retardant reinforced PPE composite material is specifically prepared from the following raw materials in parts by weight: 50-75 parts of polyphenyl ether (PPE) resin, 15-30 parts of chopped glass fiber subjected to surface pretreatment, 3-15 parts of a solid organic phosphate flame retardant, 0.5-3 parts of a sulfonate flame retardant and 0.5-3 parts of a flame-retardant synergist. The chopped glass fiber subjected to surface pretreatment is a chopped glass fiber subjected to pre-impregnation treatment by compounding an epoxy group-terminated organic silicon prepolymer with an organic silicon phosphorus flame retardant; the preparation method has the advantages that aiming at the requirements of a current new energy automobile on high flame retardance and high insulation stability of a flame-retardant reinforced PPE composite material under complex environmental factors such as high temperature and high humidity, an epoxy group-terminated organic silicon prepolymer is compounded with a silicon-phosphorus flame retardant to pre-impregnate a glass fiber reinforcement; and the prepolymer is further polymerized during melt extrusion to form a compact interface layer structure, and meanwhile, effective protection is provided for the organic silicon-phosphorus flame retardant.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation, and its preparation method. Background Technology

[0002] Polyphenylene oxide (PPO) is a high-performance special engineering plastic with a rigid benzene ring molecular backbone structure. It has extremely excellent mechanical properties and dimensional stability. Its water absorption rate and linear expansion coefficient are the lowest among commonly used polymer materials. Due to its specific chemical structure, it also has relatively high flame retardant properties. When used in combination with new halogen-free flame retardants and high-performance inorganic reinforcing fibers, its mechanical properties and flame retardancy can be further enhanced. It is one of the typical materials for the current research and application of high-performance special polymers. It is especially suitable for the most core components of the "three electrics (drive motor, power battery, and electronic control system)" in new energy vehicles.

[0003] However, for flame-retardant reinforced PPE composites, although the PPE matrix resin itself has excellent hydrolysis resistance, the material contains many components and is highly polar, which can easily lead to performance instability in complex external environments. For example, in high temperature and high humidity environments, the rapid diffusion of moisture into the material, coupled with the activation effect of high temperature, and the lack of effective protection and the instability of the halogen-free flame retardant which is itself easily hydrolyzed, can have a serious negative impact on the performance of PPE composites. Therefore, achieving good mechanical properties, flame retardant characteristics, and electrical properties in harsh external environments is the key to whether flame-retardant reinforced PPE composites can be widely promoted and applied in the target field of new energy vehicles. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation properties, comprising the following raw materials in parts by weight:

[0007]

[0008]

[0009] The surface-pretreated short-cut glass fibers are short-cut glass fibers pre-impregnated with epoxy-terminated organosilicon prepolymer and organosilicon-phosphorus flame retardant.

[0010] Furthermore, the polyphenylene oxide resin is a modified polyoxyethylene resin (MPPO) with a molecular weight of 22,000-49,000 and a melt flow index (MFR) of 2-15 g / 10 min under test conditions of 280°C and 5 kg.

[0011] Furthermore, the surface-pretreated chopped glass fibers are polyphenylene ether-specific chopped glass fiber mats pre-impregnated with epoxy-terminated organosilicon prepolymers and organosilicon-phosphorus synergistic flame retardants. The fiber monofilament diameter is 10-13 μm and the chopped length is 3 mm.

[0012] Furthermore, the solid organophosphate flame retardant is characterized by being one or more novel, highly efficient, and heat-resistant solid organic aluminum hypophosphite flame retardants or organic zinc hypophosphite flame retardants.

[0013] Furthermore, the sulfonate flame retardant is a high-purity diphenyl sulfonate flame retardant, KSS FR, a white powder.

[0014] Furthermore, the flame retardant synergist is a polytetrafluoroethylene-based high-efficiency flame retardant and anti-dripping agent with a particle size range of 100–500 μm.

[0015] Furthermore, the epoxy-terminated organosilicon prepolymer is a linear bifunctional epoxy-terminated reactive organosilicon prepolymer, a colorless and transparent liquid with a viscosity range of 3000–5000 CPS.

[0016] Furthermore, the organosilicon-phosphorus flame retardant is a novel synergistic flame retardant with an effective phosphorus content of 20% and an average particle size (D50) of 30 μm.

[0017] The second objective of this invention is to provide a method for preparing the flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 1, characterized in that:

[0018] (1) Weigh PPE resin, sulfonate flame retardant and flame retardant synergist according to the weight percentages mentioned above, mix them evenly to obtain mixed raw materials;

[0019] (2) After drying the above mixed raw materials, they are placed in the main feed bin of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the barrel of the extruder. The surface-pretreated chopped glass fibers are fed into the extruder from the side feed port 1, which is located in the 4th section of the extruder. The solid organophosphate flame retardant is fed into the extruder from the side feed port 2, which is located in the 6th section of the extruder. The diameter of the extruder screw is 35 mm, the length-to-diameter ratio L / D is 56, and the temperature of each section of the main barrel from the feed port to the die head outlet is set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) Firstly, in view of the inherent defect of weak interface in traditional inorganic fiber reinforced composite material system, and considering that the direct melt mixing of complex and diverse flame retardant additive system with inorganic fiber reinforcement is not effective, the technical solution of this invention first uses a linear bifunctional group epoxy-terminated reactive organosilicon prepolymer to pre-impregnate the short glass fiber reinforcement. While stirring and dispersing at high speed, organosilicon phosphorus flame retardant is added, so as to uniformly distribute and coat the organosilicon prepolymer and flame retardant on the surface of the reinforced glass fiber. When the functional group-terminated organosilicon prepolymer melts at high temperature inside the extruder, it further undergoes chain growth to form a high-strength and elastic interface layer structure, thus providing a structural basis for achieving a strong interface bond between glass fiber and PPE matrix.

[0022] (2) In response to the problems of poor hydrolysis resistance, easy decomposition and unstable flame retardant performance of conventional flame retardant additive systems such as organophosphates, solid metal phosphate flame retardants are optimized and selected, thereby improving the performance stability of the flame retardant system in high temperature and high humidity environments.

[0023] (3) The high-performance PPE composite material prepared by the technical solution of the present invention not only has good comprehensive performance in the conventional environment (23℃, 50%RH), but also retains more than 80% of its tensile strength after being stored in a high temperature and high humidity environment (85℃, 85%RH) for 500 hours, which is a significant improvement over conventional flame-retardant reinforced PPE materials. Vertical burning test shows that the flame retardant level of the material still meets the UL94 V-0 (0.8mm) level requirements, which is consistent with the performance in the conventional environment. The CTI tracking index of the material is measured to be moderately maintained above 800V. Its excellent electrical insulation stability is especially suitable for the material selection requirements of the "three electrics" system components of new energy vehicles. Detailed Implementation

[0024] The present invention will be further described below through specific embodiments. These embodiments are only used to illustrate the present invention and are not intended to limit the present invention.

[0025] Raw materials used in the embodiments of this invention:

[0026] PPE-1: Noryl V0150B polyphenylene oxide, with a melt flow index (MFR) of 3.5 g / 10 min under test conditions of 280°C and 5 kg, produced by SABIC Basic Innovative Plastics, USA.

[0027] PPE-2: Polyphenylene oxide LXR35, with a melt flow index (MFR) of 13 g / 10 min under test conditions of 280℃ and 5 kg, Lanxing Chemical New Materials Co., Ltd.

[0028] Chopped Fiberglass-1: ECS-T551R, monofilament diameter 13um, chopped length 3mm, Shandong Taishan Fiberglass Co., Ltd.

[0029] Chopped Fiberglass-2: ECS-540H, monofilament diameter 10um, chopped length 3mm, China Jushi Co., Ltd.

[0030] Organic hypophosphite flame retardant: aluminum hypophosphite OP-935, Klein, Switzerland, available phosphorus content: 23-24%.

[0031] Organic hypophosphite flame retardant: Zinc hypophosphite ZX-ZDP950, Tianjin Zhenxing Chemical, available phosphorus content: 21-24%.

[0032] Organosilicon prepolymer: Slimer EP Di-50 epoxy-functionalized organosilicon prepolymer, colorless and transparent liquid, viscosity 4500 CPS, Stey Chemicals, Canada.

[0033] Organosilicon phosphorus flame retardant: FR-ASP, white powder, effective phosphorus content 20%, moisture content ≤0.2%, average particle size D50 is 30um.

[0034] Sulfonate flame retardant: High-purity diphenyl sulfonate KSS FR F-535, white powder.

[0035] Flame retardant synergist: Polytetrafluoroethylene anti-dripping agent, white powder, product purity 100%, average particle size D98 is 500um.

[0036] Product performance testing:

[0037] Tensile properties: Tested according to ISO 527-2 standard at a test rate of 50 mm / min.

[0038] Notched impact performance: Tested on a simply supported beam impact testing machine according to ISO 179-1 standard, with type A notch on the specimen, at room temperature (23℃).

[0039] Flame retardant performance: Tested according to the UL94 vertical burning standard test method in a Derrick DRK-310 horizontal and vertical burning tester, with a test strip thickness of 0.8 mm.

[0040] CTI Tracking Index: Tested according to the standard method of GB / T 4207-2012;

[0041] Aging test in a humid and hot environment: standard tensile and flame-retardant specimens were prepared and placed in a constant temperature and humidity chamber at 85℃ and 85%RH for 500 hours. After the test, the tensile strength and flame retardancy rating of the specimens were tested.

[0042] Example 1

[0043] Weigh the PPE resin, sulfonate flame retardant, and flame retardant synergist according to the weight percentages described in Example 1 of Table 1, mix them evenly, and obtain the mixed raw materials.

[0044] After drying, the above-mentioned mixed raw materials are placed in the main feed hopper of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the extruder barrel. Surface-pretreated chopped glass fibers are added into the extruder through side feed port 1, located in the fourth section of the extruder. Solid organophosphate flame retardants are added into the extruder through side feed port 2, located in the sixth section of the extruder. The extruder screw diameter is 35 mm, and the length-to-diameter ratio (L / D) is 56. The temperatures of each zone in the main barrel from the feed port to the die outlet are set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation, and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

[0045] Example 2

[0046] Weigh the PPE resin, sulfonate flame retardant, and flame retardant synergist according to the weight percentages described in Example 2 of Table 1, mix them evenly, and obtain the mixed raw materials.

[0047] After drying, the above-mentioned mixed raw materials are placed in the main feed hopper of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the extruder barrel. Surface-pretreated chopped glass fibers are added into the extruder through side feed port 1, located in the fourth section of the extruder. Solid organophosphate flame retardants are added into the extruder through side feed port 2, located in the sixth section of the extruder. The extruder screw diameter is 35 mm, and the length-to-diameter ratio (L / D) is 56. The temperatures of each zone in the main barrel from the feed port to the die outlet are set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation, and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

[0048] Example 3

[0049] Weigh the PPE resin, sulfonate flame retardant, and flame retardant synergist according to the weight percentages described in Example 3 of Table 1, mix them evenly, and obtain the mixed raw materials.

[0050] After drying, the above-mentioned mixed raw materials are placed in the main feed hopper of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the extruder barrel. Surface-pretreated chopped glass fibers are added into the extruder through side feed port 1, located in the fourth section of the extruder. Solid organophosphate flame retardants are added into the extruder through side feed port 2, located in the sixth section of the extruder. The extruder screw diameter is 35 mm, and the length-to-diameter ratio (L / D) is 56. The temperatures of each zone in the main barrel from the feed port to the die outlet are set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation, and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

[0051] Example 4

[0052] Weigh the PPE resin, sulfonate flame retardant, and flame retardant synergist according to the weight percentages described in Example 4 of Table 1, mix them evenly, and obtain the mixed raw materials.

[0053] After drying, the above-mentioned mixed raw materials are placed in the main feed hopper of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the extruder barrel. Surface-pretreated chopped glass fibers are added into the extruder through side feed port 1, located in the fourth section of the extruder. Solid organophosphate flame retardants are added into the extruder through side feed port 2, located in the sixth section of the extruder. The extruder screw diameter is 35 mm, and the length-to-diameter ratio (L / D) is 56. The temperatures of each zone in the main barrel from the feed port to the die outlet are set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation, and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

[0054] Example 5

[0055] Weigh the PPE resin, sulfonate flame retardant, and flame retardant synergist according to the weight percentages described in Example 5 of Table 1, mix them evenly, and obtain the mixed raw materials.

[0056] After drying, the above-mentioned mixed raw materials are placed in the main feed hopper of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the extruder barrel. Surface-pretreated chopped glass fibers are added into the extruder through side feed port 1, located in the fourth section of the extruder. Solid organophosphate flame retardants are added into the extruder through side feed port 2, located in the sixth section of the extruder. The extruder screw diameter is 35 mm, and the length-to-diameter ratio (L / D) is 56. The temperatures of each zone in the main barrel from the feed port to the die outlet are set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation, and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

[0057] Example 6

[0058] Weigh the PPE resin, sulfonate flame retardant, and flame retardant synergist according to the weight percentages described in Example 6 of Table 1, mix them evenly, and obtain the mixed raw materials.

[0059] After drying, the above-mentioned mixed raw materials are placed in the main feed hopper of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the extruder barrel. Surface-pretreated chopped glass fibers are added into the extruder through side feed port 1, located in the fourth section of the extruder. Solid organophosphate flame retardants are added into the extruder through side feed port 2, located in the sixth section of the extruder. The extruder screw diameter is 35 mm, and the length-to-diameter ratio (L / D) is 56. The temperatures of each zone in the main barrel from the feed port to the die outlet are set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation, and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

[0060] Table 1. Formulation of flame-retardant reinforced PPE composite materials with excellent hydrolysis resistance and electrical insulation (unit: grams)

[0061]

[0062]

[0063] Comparative Example 1

[0064] Flame-retardant reinforced PPE grade G702V, 20% glass fiber reinforced, Asahi Kasei Corporation, Japan, commercially available.

[0065] Table 2. Test results of flame-retardant reinforced PPE composite materials with excellent hydrolysis resistance and electrical insulation.

[0066]

[0067] From the material performance test data of Examples 1-6 in Table 2, it can be seen that the mechanical properties, flame retardant properties and long-term stability of flame-retardant reinforced PPE composite materials are closely related to many factors such as the type of PPE resin, the content of glass fiber reinforcement, the type and amount of flame retardant, and the types of other additives. Therefore, it is necessary to use specific formulation combinations to maximize its own advantages.

[0068] Comparing Examples 1 and 2, it can be seen that as the content of glass fiber reinforcement in the component materials gradually increases, the key indicators such as tensile strength and flame retardancy of the materials are significantly improved, and the flame retardancy rating under normal conditions is also improved from V-1 to V-0. However, excessive use of glass fiber can easily lead to an increase in the proportion of the interface layer in the PPE material, which in turn leads to an increase in the number of interface defects. Therefore, the performance degradation is very obvious after a long-term (500h) damp heat aging test. In Examples 5 and 6, an appropriate proportion (20%) of glass fiber was used, and its performance before and after aging was significantly more stable.

[0069] Compared to Comparative Example 1 with the same glass fiber content, Example 6, which exhibits the best performance, demonstrates significantly higher retention rates of flame retardancy and tensile strength before and after humid heat aging. This is attributed to the glass fiber pre-impregnation treatment and the appropriate selection of the flame retardant auxiliary system and dosage. Its tensile strength retention rate reaches 84%, the flame retardancy rating remains UL94 V-0 (0.8mm), and the CTI value is at an extremely high level of 895V. In contrast, Comparative Example 1 shows a tensile strength retention rate of only 61%, a severely reduced flame retardancy rating to UL94 V-2 (0.8mm), and a significantly lower CTI value to 415V. The flame-retardant reinforced PPE composite material obtained according to the technical solution of this invention exhibits excellent and stable performance in key performance indicators such as mechanical properties, flame retardancy, and electrical insulation properties in long-term humid heat environments. This provides a solid and powerful performance foundation for its continued and in-depth promotion and application in the target field of new energy vehicles.

Claims

1. A flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation, characterized in that: Including the following raw materials by weight: The surface-pretreated short-cut glass fibers are short-cut glass fibers pre-impregnated with epoxy-terminated organosilicon prepolymer and organosilicon-phosphorus flame retardant.

2. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 1, characterized in that: The polyphenylene oxide resin is a modified polyoxyethylene resin (MPPO) with a molecular weight of 22,000-49,000 and a melt flow index (MFR) of 2-15 g / 10 min under test conditions of 280°C and 5 kg.

3. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 1, characterized in that: The surface-pretreated chopped glass fibers are polyphenylene ether-specific chopped glass fiber mats pre-impregnated with epoxy-terminated organosilicon prepolymer and organosilicon-phosphorus synergistic flame retardant. The fiber monofilament diameter is 10-13 μm and the chopped length is 3 mm.

4. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 1, characterized in that: The solid organophosphate flame retardant is characterized by being a novel, highly efficient, and heat-resistant solid organic aluminum hypophosphite flame retardant or an organic zinc hypophosphite flame retardant, or one or more of these.

5. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 1, characterized in that: The sulfonate flame retardant mentioned is high-purity diphenyl sulfonate flame retardant KSS FR, a white powder.

6. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 1, characterized in that: The flame retardant synergist is a polytetrafluoroethylene-based high-efficiency flame retardant and anti-dripping agent with a particle size range of 100–500 μm.

7. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 1, characterized in that: The preparation method of the surface-pretreated chopped glass fibers is as follows: a certain proportion of polyphenylene ether-specific chopped glass fiber mat sheets are weighed and put into a vacuum high-speed mixer; a certain proportion of epoxy-terminated organosilicon prepolymer is weighed in a glass beaker, and an appropriate amount of cyclohexane is added for dilution and viscosity reduction. Then, a certain proportion of organosilicon phosphorus flame retardant powder is added under stirring conditions at room temperature (23℃). After stirring at low speed for 15 minutes, the mixture is added to the vacuum high-speed mixer. The mixer is turned on, the speed is set to 1000 rpm, and the vacuum degree is -0.1 MPa. After stirring for 15 minutes, the surface-pretreated chopped glass fibers are obtained.

8. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 7, characterized in that: The epoxy-terminated organosilicon prepolymer is a linear bifunctional epoxy-terminated reactive organosilicon prepolymer, a colorless and transparent liquid with a viscosity range of 3000–5000 CPS.

9. The flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation as described in claim 7, characterized in that: The organosilicon-phosphorus flame retardant is a novel synergistic flame retardant with an effective phosphorus content of 20% and an average particle size (D50) of 30 μm.

10. The method for preparing the flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation according to any one of claims 1-9, characterized in that: The steps are as follows: (1) Weigh PPE resin, sulfonate flame retardant and flame retardant synergist according to the weight percentages mentioned above, mix them evenly to obtain mixed raw materials; (2) After drying the above mixed raw materials, they are placed in the main feed bin of a tightly meshed co-directional twin-screw extruder with dual side feeding. The feed screws feed the materials into the barrel of the extruder. The surface-pretreated chopped glass fibers are fed into the extruder from the side feed port 1, which is located in the 4th section of the extruder. The solid organophosphate flame retardant is fed into the extruder from the side feed port 2, which is located in the 6th section of the extruder. The diameter of the extruder screw is 35 mm, the length-to-diameter ratio L / D is 56, and the temperature of each section of the main barrel from the feed port to the die head outlet is set as follows: 150℃, 220℃, 230℃, 245℃, 250℃, 240℃, 240℃, 240℃, 240℃. The main machine speed is 350 rpm. After melt extrusion, cooling, granulation and drying, a flame-retardant reinforced PPE composite material with excellent hydrolysis resistance and electrical insulation is obtained.

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