Sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material and preparation method thereof

Abstract

The invention discloses a sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material and a preparation method thereof, and belongs to the technical field of high polymer materials. The sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material is prepared from the following raw materials in parts by mass: 35 to 55 parts of polypropylene resin, 5 to 35 parts of hollow glass beads, 2 to 10 parts of a compatilizer, 20 to 24 parts of a halogen-free flame retardant, 0.1 to 0.4 part of a main oxidant, 0.2 to 0.8 part of an auxiliary antioxidant, 0.1 to 0.4 part of a lubricant and 0.1 to 0.2 part of an anti-dripping agent. The material has excellent flame retardant property, high strength, good mechanical property and sound absorption and sound insulation functions, and a product can be applied to the fields of household appliances, electronic appliances and automobiles, is particularly suitable for flame retardant structural parts of various small household appliances, such as pump shells, motor outer covers and other parts, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is a thermoplastic resin formed by the polymerization of propylene. It has a milky white granular appearance, a density of 0.89-0.91g / cm3, is cheap, has good formability, and a processing temperature of about 200°C. It has stable performance after forming and excellent acid and alkali corrosion resistance. It is widely used in household appliance housings, structural parts, automobile bumpers, door panels, and interior decoration.

[0003] In some applications of PP, such as when PP is used in electronic component contact parts, the plastic is often required to have flame retardant function, and PP itself is flammable (oxygen limit index is only 18% vol), so PP needs to be flame retardant functionalized. The common method is to add flame retardants to PP materials by co-extrusion to modify the PP materials. Traditional bromine flame retardants have the characteristics of high flame retardant efficiency, good compatibility with plastic resins, and relatively small impact on material properties. They are often used to prepare flame retardant PP materials. In order to improve the flame retardant properties of the system, antimony oxide needs to be added. The two are easy to generate antimony bromide gas with a large specific gravity at high temperature, which surrounds the ignition point and isolates oxygen, thereby achieving the purpose of flame retardancy. This is the gas phase flame retardant mechanism of bromine flame retardants. However, the bromine antimony flame retardant system will produce a lot of black smoke while being flame retardant. Under real fire conditions, black smoke will cause trapped and rescue personnel to have obstructed vision and difficulty breathing, greatly increasing the difficulty of rescue. At the same time, bromide escapes into the air, which is also a pollution to the environment. For these reasons, halogen-free flame retardants for PP came into being. PP halogen-free flame retardants are composed of nitrogen, phosphorus and other elements. Their flame retardant mechanism is condensed phase carbonization. They are dehydrated into carbon by self-catalysis, blocking heat sources and air. The amount of smoke generated during the flame retardant process is very small, which greatly improves the shortcomings of bromine antimony flame retardants. However, halogen-free flame retardant PP also has obvious defects. First, after adding halogen-free flame retardants, the viscosity of the system increases, the melt index decreases, and the molding process becomes difficult. Second, the temperature resistance of halogen-free flame retardants is not as good as that of bromine antimony flame retardants, and black spots and other poor appearances are easily generated during the processing. Third, the compatibility of halogen-free flame retardants with PP substrates is not as good as that of bromine antimony flame retardants, which leads to a decrease in the mechanical properties of halogen-free flame retardant PP materials, especially a decrease in impact properties, and it is easy to precipitate under high temperature and high humidity environments.

[0004] And in some application scenarios of flame-retardant PP, such as pump housings, motor covers, coil insulation gaskets and other parts of small household appliances, the generation of noise is inevitable due to the rotation and vibration of metal parts. The size of the noise directly affects consumers' purchasing desire. Home appliance manufacturers take measures to reduce noise as much as possible. The most common method is to fill sound-absorbing materials such as sound insulation cotton near the noise source to reduce the spread of noise. Some plastic parts also use foam materials to absorb sound waves. However, for parts with flame retardant requirements, especially flame retardant structural parts, the strength and flame retardant properties of the foam material cannot meet the use requirements. Therefore, it is urgent to develop a flame retardant polypropylene material with both high strength and sound insulation functions. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material and a preparation method thereof, which solves the problems in the prior art.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material comprises the following raw materials in parts by weight:

[0008]

[0009]

[0010] Furthermore, the polypropylene resin includes copolymer polypropylene and homopolypropylene.

[0011] Furthermore, the compatibilizer is a resin carrier grafting group; the grafting group is maleic anhydride or glycidyl methacrylate, and the resin carrier is selected from at least one of PE, PP, and POE;

[0012] Furthermore, the halogen-free flame retardant includes melamine polyphosphate and piperazine pyrophosphate.

[0013] Further, the primary antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] or a combination thereof; the secondary antioxidant is at least one of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, dilauryl thiodipropionate, and distearyl thiodipropionate.

[0014] Furthermore, the lubricant is selected from at least one of silicone powder, pentaerythritol stearate, calcium stearate, zinc stearate, aluminum stearate, and ethylene bis stearamide.

[0015] Furthermore, the anti-dripping agent is polytetrafluoroethylene powder, modified polytetrafluoroethylene powder or a combination thereof.

[0016] The method for preparing the above-mentioned sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material comprises the following steps:

[0017] S1, weighing polypropylene resin, compatibilizer, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant and anti-dripping agent according to mass parts, and mixing them using a high-speed mixer;

[0018] S2, adding the above-mentioned mixed material into a twin-screw extruder through a main feeding port, and adding the hollow glass microspheres through a side feeding port, and melt-extruding and granulating together with the mixed material in the main feeding port.

[0019] Furthermore, the process parameters of the twin-screw extruder are: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the die head temperature is 205°C, the screw speed is 150-300rpm, and the vacuum degree is -0.06--0.04MPa.

[0020] The above-mentioned sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material is used in the preparation of household appliance casings.

[0021] Beneficial effects of the present invention:

[0022] 1. The addition of hollow glass beads not only improves the rigidity of the material, but also improves the sound absorption coefficient of the material, giving the material sound insulation function.

[0023] 2. The main component of hollow glass microspheres is SiO2, and its surface contains strong polar groups such as hydroxyl groups, which have poor compatibility with PP resins with low polarity. The present invention improves the interface structure between PP resin and hollow glass microspheres by introducing a compatibilizer, solves the problem of poor compatibility between hollow glass microspheres and PP resin, and improves the mechanical properties of the material; PP is a non-polar material, and its saturated molecular chain is composed of carbon and hydrogen, so it lacks polar groups, resulting in its low polarity; this non-polar property makes polypropylene have poor performance when bonding polar materials because the interaction between polar materials and non-polar materials is weak. Compared with polar materials such as PA, PBT, and PC, PP has poor bonding strength with hollow glass microspheres and cannot be used directly.

[0024] 3. The present invention improves the process and adopts the side feeding method to add the hollow glass microspheres, thereby avoiding the problem of excessive shearing and crushing of the hollow glass microspheres during main feeding, which leads to the decrease of mechanical properties and sound absorption performance of the material.

[0025] 4. The PP material of the present invention has excellent flame retardant properties, high strength and good mechanical properties, sound absorption and sound insulation functions. The products can be used in household appliances, electronic appliances, and automobile fields, especially suitable for various small household flame retardant structural parts, such as pump housings, motor covers and other components, and have broad application prospects. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. 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.

[0027] A sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material comprises the following raw materials in parts by weight:

[0028]

[0029] The polypropylene resin includes copolymer polypropylene and homopolymer polypropylene, and has a density of 0.89-0.91 g / cm 3 ;

[0030] The specific gravity of the hollow glass microspheres is 0.2-0.6 g / cm 3 ;

[0031] The compatibilizer is a resin carrier grafting group; the grafting group is maleic anhydride or glycidyl methacrylate, and the resin carrier is selected from at least one of PE, PP, and POE;

[0032] The halogen-free flame retardant is: HF-800A (which includes melamine polyphosphate and piperazine pyrophosphate).

[0033] The primary antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] or a combination thereof; the secondary antioxidant is at least one of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, dilauryl thiodipropionate, and distearyl thiodipropionate.

[0034] The lubricant is selected from at least one of silicone powder, pentaerythritol stearate, calcium stearate, zinc stearate, aluminum stearate, and ethylene bis stearamide.

[0035] The anti-dripping agent is polytetrafluoroethylene powder, modified polytetrafluoroethylene powder or a combination thereof.

[0036] The preparation method of the sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material comprises the following steps:

[0037] S1, weighing polypropylene resin, compatibilizer, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to weight proportions, and mixing them using a high-speed stirrer;

[0038] S2, adding the above-mentioned mixed material into a twin-screw extruder through a main feeding port, and adding the hollow glass microspheres through a side feeding port, and melt-extruding and granulating together with the mixed material in the main feeding port.

[0039] The mixing speed of the high-speed mixer is 500-1200 r / min; the temperature of the melt extrusion is as follows: the temperature of zone 1 is 150°C, the temperature of zone 2 is 180°C, the temperature of zone 3 is 180°C, the temperature of zone 4 is 190°C, the temperature of zone 5 is 190°C, the temperature of zone 6 is 180°C, the temperature of zone 7 is 180°C, the temperature of zone 8 is 190°C, and the die head temperature is 200°C; the screw speed of the twin-screw extruder is 150-300 rpm, and the vacuum degree is -0.06--0.04 MPa.

[0040] The technical scheme of the present invention is described in detail below through the following examples and comparative examples; wherein the raw materials in the comparative examples and examples are as follows:

[0041] Polypropylene resin: melt index is 8-10g / 10min (230℃ / 2.16kg), purchased from Guangzhou Branch of Sinopec;

[0042] Hollow glass microspheres: specific gravity is 0.46g / cm 3 , purchased from Zhengzhou Shenglait Hollow Microsphere New Materials Co., Ltd.;

[0043] Compatibilizer: PP grafted with maleic anhydride, with a grafting rate of maleic anhydride groups of 1-2%, purchased from Jiayirong Polymer (Shanghai) Co., Ltd.;

[0044] Halogen-free flame retardant: HF-800A, purchased from Zhongshan Sutebao New Materials Co., Ltd.

[0045] Glass fiber: TCR438G-14-4.5, purchased from Taishan Glass Fiber Co., Ltd.;

[0046] Primary antioxidant 1010: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, purchased from Tianjin Lianlong New Materials Co., Ltd.;

[0047] Auxiliary antioxidant 168: tris(2,4-di-tert-butylphenyl) phosphite, purchased from Tianjin Lianlong New Materials Co., Ltd.;

[0048] Lubricant: ethylene bis stearamide (EBS), purchased from Guangzhou Yinuo Chemical Technology Co., Ltd.;

[0049] Anti-dripping agent: modified polytetrafluoroethylene, DB105, purchased from Shanghai Puxin Polymer Materials Co., Ltd.

[0050] Example 1

[0051] A high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation, comprising the following raw materials in parts by weight:

[0052]

[0053] The preparation method of the above-mentioned high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation comprises the following steps:

[0054] S1, weigh polypropylene resin, compatibilizer, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to their mass fractions, and mix them using a high-speed stirrer at 600 rpm.

[0055] S2, adding the mixed material prepared in S1 into a parallel twin-screw extruder through a main feeder, and performing melt extrusion and granulation in the parallel twin-screw extruder;

[0056] The process parameters are as follows: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the temperature of die head is 205°C, the screw speed is 250rpm, the vacuum degree is -0.05MPa; the ratio of screw length L to diameter D L / D is 35; the screw is provided with 1 meshing block area and 1 reverse thread area;

[0057] S3, adding hollow glass microspheres according to the mass fraction into a weighing scale, and adding them into a parallel twin-screw extruder through a side feed port, wherein the side feed port is arranged between the fourth zone and the fifth zone;

[0058] Under the above process conditions, a granular sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material is obtained by melt extrusion and granulation through a twin-screw extruder.

[0059] Example 2

[0060] A high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation, comprising the following raw materials in parts by weight:

[0061]

[0062] The preparation method of the above-mentioned high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation comprises the following steps:

[0063] S1, weigh polypropylene resin, compatibilizer, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to their mass fractions, and mix them using a high-speed stirrer at 600 rpm.

[0064] S2, adding the mixed material prepared in S1 into a parallel twin-screw extruder through a main feeder, and performing melt extrusion and granulation in the parallel twin-screw extruder;

[0065] The process parameters are as follows: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the temperature of die head is 205°C, the screw speed is 250rpm, the vacuum degree is -0.05MPa; the ratio of screw length L to diameter D L / D is 35; the screw is provided with 1 meshing block area and 1 reverse thread area;

[0066] S3, adding hollow glass microspheres according to the mass fraction into a weighing scale, and adding them into a parallel twin-screw extruder through a side feed port, wherein the side feed port is arranged between the fourth zone and the fifth zone;

[0067] Under the above process conditions, a granular sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material is obtained by melt extrusion and granulation through a twin-screw extruder.

[0068] Comparative Example 1

[0069] A polypropylene material, comprising the following raw materials in parts by weight:

[0070]

[0071] The preparation method of the above-mentioned high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation comprises the following steps:

[0072] S1, weigh polypropylene resin, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to their mass fractions, and mix them using a high-speed stirrer at 600 rpm.

[0073] S2, adding the mixed material prepared in S1 into a parallel twin-screw extruder through a main feeder, and performing melt extrusion and granulation in the parallel twin-screw extruder;

[0074] The process parameters are as follows: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the temperature of die head is 205°C, the screw speed is 250rpm, the vacuum degree is -0.05MPa; the ratio of screw length L to diameter D L / D is 35; the screw is provided with 1 meshing block area and 1 reverse thread area;

[0075] Under the above process conditions, a granular sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material is obtained by melt extrusion and granulation through a twin-screw extruder.

[0076] Comparative Example 2

[0077] A polypropylene material, comprising the following raw materials in parts by weight:

[0078]

[0079] The preparation method of the above-mentioned high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation comprises the following steps:

[0080] S1, weigh polypropylene resin, compatibilizer, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to their mass fractions, and mix them using a high-speed stirrer at 600 rpm.

[0081] S2, adding the mixed material prepared in S1 into a parallel twin-screw extruder through a main feeder, and performing melt extrusion and granulation in the parallel twin-screw extruder;

[0082] The process parameters are as follows: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the temperature of die head is 205°C, the screw speed is 250rpm, the vacuum degree is -0.05MPa; the ratio of screw length L to diameter D L / D is 35; the screw is provided with 1 meshing block area and 1 reverse thread area;

[0083] S3, adding glass fibers according to the mass fraction into a weighing scale, and feeding into a parallel twin-screw extruder through a side feed port, wherein the side feed port is arranged between the fourth zone and the fifth zone;

[0084] Under the above process conditions, a granular sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material is obtained by melt extrusion and granulation through a twin-screw extruder.

[0085] Comparative Example 3

[0086] A polypropylene material, comprising the following raw materials in parts by weight:

[0087]

[0088] The preparation method of the above-mentioned high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation comprises the following steps:

[0089] S1, weigh polypropylene resin, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to their mass fractions, and mix them using a high-speed stirrer at 600 rpm.

[0090] S2, adding the mixed material prepared in S1 into a parallel twin-screw extruder through a main feeder, and performing melt extrusion and granulation in the parallel twin-screw extruder;

[0091] The process parameters are as follows: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the temperature of die head is 205°C, the screw speed is 250rpm, the vacuum degree is -0.05MPa; the ratio of screw length L to diameter D L / D is 35; the screw is provided with 1 meshing block area and 1 reverse thread area;

[0092] S3, adding hollow glass microspheres according to the mass fraction into a weighing scale, and adding them into a parallel twin-screw extruder through a side feed port, wherein the side feed port is arranged between the fourth zone and the fifth zone;

[0093] Under the above process conditions, a granular sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material is obtained by melt extrusion and granulation through a twin-screw extruder.

[0094] Comparative Example 4

[0095] A polypropylene material, comprising the following raw materials in parts by weight:

[0096]

[0097] The preparation method of the above-mentioned high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation comprises the following steps:

[0098] S1, weigh polypropylene resin, compatibilizer, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to their mass fractions, and mix them using a high-speed stirrer at 600 rpm.

[0099] S2, adding the mixed material prepared in S1 into a parallel twin-screw extruder through a main feeder, and performing melt extrusion and granulation in the parallel twin-screw extruder;

[0100] The process parameters are as follows: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the temperature of die head is 205°C, the screw speed is 250rpm, the vacuum degree is -0.05MPa; the ratio of screw length L to diameter D L / D is 35; the screw is provided with 1 meshing block area and 1 reverse thread area;

[0101] S3, adding hollow glass microspheres according to the mass fraction into a weighing scale, and adding them into a parallel twin-screw extruder through a side feed port, wherein the side feed port is arranged between the fourth zone and the fifth zone;

[0102] Under the above process conditions, a granular sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material is obtained by melt extrusion and granulation through a twin-screw extruder.

[0103] Comparative Example 5

[0104] A polypropylene material, comprising the following raw materials in parts by weight:

[0105]

[0106] The preparation method of the above-mentioned high-strength halogen-free flame-retardant polypropylene material for sound absorption and sound insulation comprises the following steps:

[0107] S1, weigh polypropylene resin, compatibilizer, hollow glass microspheres, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant, and anti-dripping agent according to their mass fractions, and mix them using a high-speed stirrer at 600 rpm.

[0108] S2, adding the mixed material prepared in S1 into a parallel twin-screw extruder through a main feeder, and performing melt extrusion and granulation in the parallel twin-screw extruder;

[0109] The process parameters are as follows: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the temperature of die head is 205°C, the screw speed is 250rpm, the vacuum degree is -0.05MPa; the ratio of screw length L to diameter D L / D is 35; the screw is provided with 1 meshing block area and 1 reverse thread area;

[0110] Under the above process conditions, a granular sound-absorbing and sound-insulating high-strength halogen-free flame-retardant polypropylene material is obtained by melt extrusion and granulation through a twin-screw extruder.

[0111] The raw material ratios of the embodiments and comparative examples are shown in Table 1 below;

[0112] Table 1 List of raw material compositions by weight for examples and comparative examples

[0113]

[0114] Performance Testing

[0115] The polypropylene materials prepared in the above examples and comparative examples were injection molded into national standard specimens and the following performance tests were performed. The test standards are as follows:

[0116] Density: Tested according to GB / T 1033.1-2008 standard;

[0117] Bending strength: tested according to GB / T 9341-2008 standard, bending rate is 2mm / min;

[0118] Bending modulus: tested according to GB / T 9341-2008 standard, bending rate is 2mm / min;

[0119] Notched impact strength: tested according to GB / T 1843-2008 standard, cantilever beam pendulum 2.75J;

[0120] Flame retardant grade: tested according to UL 94:2023 standard.

[0121] Sound absorption coefficient: tested according to GB / T 18696.2-2002 standard, board thickness 1.5mm.

[0122] The test results are shown in Table 2 below:

[0123] Table 2 Performance test list of polypropylene materials of embodiments and comparative examples

[0124]

[0125] From the performance test results of the above Examples 1-2 and Comparative Examples 1-5, it can be analyzed that:

[0126] (1) Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that after adding hollow glass microspheres and compatibilizers, the density of the material is reduced, the bending strength and bending modulus are improved, and more importantly, the sound absorption coefficient is greatly improved. Hollow glass microspheres are a kind of reinforced filler. Although their reinforcing effect is not as good as that of traditional glass fibers, the difference between the two is that glass fibers have an extremely high aspect ratio and a significant reinforcing effect, while hollow glass microspheres are spherical and have a relatively weak reinforcing effect. The reason for the significant increase in the sound absorption coefficient is that due to the hollow structure of the hollow glass microspheres, there is a trace amount of air inside the cavity. When the sound waves are transmitted at the resin / hollow glass microsphere interface and the matrix / cavity interface of the microspheres, they are reflected, refracted and absorbed many times, and the sound wave transmission ability is reduced. Compared with halogen-free flame retardant PP (sound absorption coefficient 0.065) and glass fiber reinforced halogen-free flame retardant PP (sound absorption coefficient 0.147), the sound absorption coefficient of the halogen-free flame retardant PP material filled with hollow glass microspheres is increased to 0.327, and the sound absorption and sound insulation effect is obvious.

[0127] (2) From Example 1 and Comparative Examples 3 and 4, it can be seen that the use of compatibilizer has almost no effect on the sound absorption coefficient, but has a great influence on the mechanical properties of the material. In Comparative Example 3, without using a compatibilizer, the flexural strength, flexural modulus, and Izod notched impact strength of the material all decreased, especially the Izod notched impact strength decreased significantly, from 9.4 kJ / m 2 Down to 2.8 kJ / m 2 . This is because the main component of hollow glass microspheres is SiO2, and its surface contains strong polar groups such as hydroxyl groups, which have poor compatibility with PP resins with lower polarity. The contact interface between the two is smooth and easy to slip when in contact, so it is not impact-resistant. The main component of the compatibilizer is polypropylene grafted with maleic anhydride, with a grafting rate of 1-2%. Maleic anhydride is a highly reactive and strongly polar group. Under the high temperature conditions of extruder shear, it can undergo dehydration condensation with the hydroxyl groups on the surface of hollow glass microspheres to form chemical bonds. The PP matrix of the compatibilizer ensures its good compatibility with the PP resin. At the same time, the reactive compatibilization of its maleic anhydride group tightly connects the hollow glass microspheres to form a whole, which is beneficial for the material to resist impact and prevent deformation and brittle fracture. However, there is an optimal addition value for the content of the compatibilizer, and the excessive amount of the compatibilizer does not significantly improve the performance of the material. For example, when 10 parts of the compatibilizer are added to Comparative Example 4, its mechanical properties are not significantly improved compared with Example 1. Since the cost of the compatibilizer is higher than that of the PP resin, considering the overall cost, adding 5 parts of the compatibilizer in Example 1 is a more cost-effective solution.

[0128] (3) The formula of Example 1 and Comparative Example 5 are exactly the same, except that the processing of Example 1 adopts side feeding, while the processing of Comparative Example 5 adopts main feeding. Different processing techniques have a significant impact on the density, mechanical properties and sound absorption and sound insulation effects of the material. When the main feeding is used, the hollow glass microspheres stay in the barrel for too long, and excessive shearing causes the structure of the hollow glass microspheres to be damaged and the hollow cavity to rupture, which causes the density to increase, the mechanical properties to decrease, and the sound absorption performance to decrease.

[0129] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0130] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material, characterized in that: Including the following raw materials by mass:

2. The sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The polypropylene resin includes copolymer polypropylene and homopolypropylene.

3. The sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The compatibilizer is a resin carrier grafting group; the grafting group is maleic anhydride or glycidyl methacrylate, and the resin carrier is selected from at least one of PE, PP, and POE.

4. The sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The halogen-free flame retardant includes melamine polyphosphate and piperazine pyrophosphate.

5. The sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The primary antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] or a combination thereof; the secondary antioxidant is at least one of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, dilauryl thiodipropionate, and distearyl thiodipropionate.

6. The sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The lubricant is selected from at least one of silicone powder, pentaerythritol stearate, calcium stearate, zinc stearate, aluminum stearate, and ethylene bis stearamide.

7. The sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The anti-dripping agent is polytetrafluoroethylene powder, modified polytetrafluoroethylene powder or a combination thereof.

8. A method for preparing a sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to any one of claims 1 to 7, comprising the following steps: S1, weighing polypropylene resin, compatibilizer, halogen-free flame retardant, primary antioxidant, secondary antioxidant, lubricant and anti-dripping agent according to mass parts, and mixing them using a high-speed mixer; S2, adding the above-mentioned mixed material into a twin-screw extruder through a main feeding port, and adding the hollow glass microspheres through a side feeding port, and melt-extruding and granulating together with the mixed material in the main feeding port.

9. The method for preparing a sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to claim 8, characterized in that: The process parameters of the twin-screw extruder are: the temperature of zone 1 is 155°C, the temperature of zone 2 is 195°C, the temperature of zone 3 is 195°C, the temperature of zone 4 is 205°C, the temperature of zone 5 is 205°C, the temperature of zone 6 is 195°C, the temperature of zone 7 is 195°C, the temperature of zone 8 is 205°C, the die head temperature is 205°C, the screw speed is 150-300rpm, and the vacuum degree is -0.06 to -0.04MPa.

10. Use of the sound-absorbing and sound-insulating halogen-free flame-retardant polypropylene material according to any one of claims 1 to 7 in the preparation of household appliance casings.

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