Wave-absorbing filler and preparation method thereof as well as polyamide composite material and preparation method thereof

Abstract

The invention provides a wave-absorbing filler and a preparation method thereof, and a polyamide composite material and a preparation method thereof. The wave-absorbing filler comprises the following components in percentage by weight: 35-40% of an inorganic conductive material, 35-55% of a magnetic material and 5-30% of a modifier; wherein the inorganic conductive material is conductive, the magnetic material has magnetism, the modifier has an amide functional group, the dispersant coats the inorganic conductive material to form a modified inorganic conductive material, and the dispersant coats the magnetic material to form a modified magnetic material. The polyamide composite material is prepared from the following components in percentage by weight: 61 to 76 percent of polyamide 6, 2 to 5 percent of wave-absorbing filler, 20 to 30 percent of basalt fiber, 1 to 2 percent of dispersing agent and 1 to 2 percent of antioxidant.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a wave-absorbing filler and a preparation method thereof, and a polyamide composite material and a preparation method thereof. Background Art

[0002] With the widespread application of voice recognition technology, TV far-field voice recognition technology has become one of the necessary technical solutions. However, there are still certain barriers to the application of voice recognition technology in the center base of the TV. Specifically, since the TV far-field voice module is placed at the front end of the center base, during the far-field signal transmission process, part of the signal is directly received by the module, and the other part of the signal is received after being reflected by the base, resulting in signal superposition. However, this superposition will weaken the signal strength, resulting in the received signal level being insufficient to meet the requirements, and then the problem of unclear signal recognition will occur. Summary of the invention

[0003] The object of the present invention is to provide a wave-absorbing filler and a preparation method thereof, a polyamide composite material and a preparation method thereof, so as to solve the problems in the prior art.

[0004] In order to solve the above technical problems, the present invention provides a wave absorbing filler, which comprises, by weight percentage, 35-40% of an inorganic conductive material, 35-55% of a magnetic material, and 5-30% of a modifier;

[0005] The inorganic conductive material is conductive, the magnetic material is magnetic, the modifier has an amide functional group, the dispersant is coated on the inorganic conductive material to form a modified inorganic conductive material, and the dispersant is coated on the magnetic material to form a modified magnetic material.

[0006] In one embodiment, the inorganic conductive material includes at least one of graphite, silicon carbide or carbon fiber.

[0007] In one embodiment, the magnetic material includes at least one of an iron-nickel alloy, iron powder and ferrite.

[0008] In one embodiment, the modifier includes at least one of PVP10, polyacrylamide and KH550.

[0009] The present invention also provides a method for preparing a wave-absorbing filler, comprising the following steps:

[0010] In terms of weight percentage, 35-40% of an inorganic conductive material, 35-55% of a magnetic material and 5-30% of a modifier are weighed;

[0011] The modifier is mixed with the inorganic conductive material and ultrasonically dispersed in an ethanol solvent for 20 to 30 minutes at a dispersion temperature of 30°C to 50°C to obtain a modified inorganic conductive material; the modifier is mixed with the magnetic material and ultrasonically dispersed in an ethanol solvent for 20 to 30 minutes at a dispersion temperature of 30°C to 50°C to obtain a modified magnetic material; the modified inorganic conductive material and the modified magnetic material are uniformly mixed to obtain a third mixture;

[0012] The third mixture is filtered and dried to obtain the wave absorbing filler.

[0013] The present invention also provides a polyamide composite material, which comprises, by weight percentage, 61-76% of polyamide 6, 2-5% of wave-absorbing filler, 20-30% of basalt fiber, 1-2% of dispersant and 1-2% of antioxidant;

[0014] Wherein, the wave-absorbing filler is the wave-absorbing filler as described above or the wave-absorbing filler prepared as described above.

[0015] In one embodiment, the melt index of the polyamide 6 is in the range of 15 to 30 g / min.

[0016] In one embodiment, the length of the basalt fiber is 1 to 15 mm; and / or,

[0017] The length of the basalt fiber is 10 to 25 mm.

[0018] In one embodiment, the dispersant includes at least one of stearamide, sodium dodecylbenzene sulfonate, and polyvinyl pyrrolidone;

[0019] The antioxidant includes at least one of antioxidant 1010 , antioxidant 168 , and antioxidant 626 .

[0020] The present invention also provides a method for preparing a polyamide composite material, comprising the following steps:

[0021] According to weight percentage, 61-76% of polyamide 6, 2-5% of absorbing filler, 20-30% of basalt fiber, 1-2% of dispersant and 1-2% of antioxidant are weighed and mixed to obtain a premix; wherein the absorbing filler is the absorbing filler as described above or the absorbing filler prepared as described above;

[0022] The premix is ​​placed in a twin-screw extruder for melt plasticization, and then granulated to obtain a masterbatch, the plasticization temperature is 280-300° C., and the rotation speed is 60-100 r / min;

[0023] placing the masterbatch in a homogenizing furnace for homogenization;

[0024] The homogenized masterbatch is dried at 80-90° C. for 3-4 hours to obtain the polyamide composite material.

[0025] It can be seen from the above technical solution that the advantages and positive effects of the present invention are:

[0026] In the wave absorbing filler of the present invention, the surface of the modified inorganic conductive material is a modifier, and the surface of the modified magnetic material is a modifier, so basically no agglomeration will occur between the two, or between the two and other substances.

[0027] In the polyamide composite material of the present invention, the basalt fiber itself has excellent wave transmission and wave absorption properties. The network path formed by the basalt fiber can guide and divide the electromagnetic waves well. The electromagnetic waves that have been transmitted and absorbed are rapidly propagated with the help of the fiber network. After secondary absorption by the modified inorganic conductive material and the modified magnetic material of the wave-absorbing filler, the electromagnetic signals are converted into heat energy, thereby improving the reflection loss effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a flow chart of the method for preparing the wave-absorbing filler.

[0029] Figure 2 The present invention is a flow chart of the method for preparing the polyamide composite material. DETAILED DESCRIPTION

[0030] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially used for illustration purposes rather than for limiting the present invention.

[0031] In order to further illustrate the principle and structure of the present invention, preferred embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0032] It should be noted that, at present, the use of absorbing materials to weaken the signal reflection effect is one of the mainstream solutions in the aviation industry and 5G communications. Usually, the aviation industry adopts a surface coating solution, and the 5G industry adopts the addition of fillers with absorbing effects to achieve this. Among them, common absorbing fillers are: conductive inorganic fillers, metal magnetic materials or their oxides, among which the conductive materials have a certain conductivity effect. The slight change of the electric field and the magnetic field causes the current and eddy current to increase, which promotes the conversion of electromagnetic energy of electromagnetic waves into thermal energy. After being affected by electromagnetic waves, the magnetic material converts the electromagnetic wave energy into thermal energy through the attenuation mechanism of natural resonance, thereby realizing the absorption and attenuation of energy. However, there are many active groups on the surface of the above-mentioned absorbing materials, so when added as fillers, they often show obvious agglomeration phenomenon, resulting in low actual electromagnetic wave absorption efficiency and low reflection loss. In addition, the stress concentration effect caused by agglomeration also affects the actual mechanical properties of the material.

[0033] Therefore, the present application provides a wave-absorbing filler which improves the agglomeration effect and also provides a method for preparing the wave-absorbing filler.

[0034] The present application also provides a polyamide composite material, which is made from the above-mentioned absorbing filler as a raw material. Based on the self-lubricating effect of the absorbing filler, the polyamide composite material improves the dispersion effect between the raw materials in the polyamide composite material, gives full play to the synergistic effect between the raw materials, forms independent small wave-transmitting and wave-absorbing units inside the material, forms a secondary wave-absorbing effect, and greatly improves the effect of the material on absorbing electromagnetic waves. In addition, the formed small units will cause a fine crystal strengthening effect, improve the polyamide crystal morphology, and make the polyamide composite material have higher strength and lower shrinkage.

[0035] Specifically, in terms of weight percentage, the wave absorbing filler includes 35-40% of inorganic conductive material, 35-55% of magnetic material and 5-30% of modifier.

[0036] Among them, the inorganic conductive material can conduct electricity, the magnetic material has magnetism, the modifier has an amide functional group, the dispersant is coated on the inorganic conductive material to form a modified inorganic conductive material, and the dispersant is coated on the magnetic material to form a modified magnetic material.

[0037] The inorganic conductive material includes at least one of graphite, silicon carbide or carbon fiber. Preferably, the inorganic conductive material is graphite.

[0038] The magnetic material includes at least one of an iron-nickel alloy, iron powder and ferrite. Preferably, the magnetic material is an iron-nickel alloy.

[0039] The modifier includes at least one of PVP10, polyacrylamide and KH550. Preferably, the modifier is PVP10.

[0040] PVP10 refers to polyvinyl pyrrolidone with an average molecular weight of 10,000. KH550 refers to γ-aminopropyltriethoxysilane.

[0041] Modifiers with amide functional groups have good self-lubricating effects, and lower molecular weights can provide lower viscosity, which helps the molecular chains diffuse into the gaps during the ultrasonic process, thereby improving the dispersion effect.

[0042] The amide group of the modifier is hydrolyzed to form a terminal carboxyl group. The carboxyl group can undergo an esterification reaction with the hydroxyl group on the surface of the inorganic conductive material, thereby coating the surface of the inorganic conductive material to obtain a modified inorganic conductive material. The carboxyl group can undergo an esterification reaction with the hydroxyl group on the surface of the magnetic material, thereby coating the surface of the magnetic material to obtain a modified magnetic material.

[0043] The surface of the modified inorganic conductive material is the modifier, and the surface of the modified magnetic material is the modifier. Therefore, there is basically no agglomeration between the two, and between the two and other substances.

[0044] See also Figure 1 The present invention also provides a method for preparing a wave absorbing filler, comprising the following steps:

[0045] S11. In terms of weight percentage, weigh 35-40% of an inorganic conductive material, 35-55% of a magnetic material, and 5-30% of a modifier.

[0046] S12. Mix the modifier with the inorganic conductive material and disperse them ultrasonically in an ethanol solvent for 20 to 30 minutes at a dispersion temperature of 30°C to 50°C to obtain a modified inorganic conductive material. Mix the modifier with the magnetic material and disperse them ultrasonically in an ethanol solvent for 20 to 30 minutes at a dispersion temperature of 30°C to 50°C to obtain a modified magnetic material. Evenly mix the modified inorganic conductive material and the modified magnetic material to obtain a third mixture.

[0047] S13, filtering the mixture after ultrasonic treatment, and drying it to obtain a wave absorbing filler.

[0048] The preparation method of the wave-absorbing filler is simple and easy to operate.

[0049] The polyamide composite material using the above-mentioned absorbing filler as raw material is specifically introduced below.

[0050] The polyamide composite material comprises, by weight percentage, 61-76% polyamide 6, 2-5% absorbing filler, 20-30% basalt fiber, 1-2% dispersant and 1-2% antioxidant, wherein the absorbing filler is the above-mentioned absorbing filler.

[0051] Polyamide 6 (PA6 for short), chemical formula is (C6 H 11 NO) n , the molecular formula is [-NH-(CH 2 ) 5 -CO] n -. The monomer of polyamide 6 is caprolactam, and it is obtained by polymerization of caprolactam.

[0052] The melt index of polyamide 6 is in the range of 15 to 30 g / min. Preferably, the melt index of polyamide 6 is in the range of 25 to 30 g / min.

[0053] Basalt fiber is a continuous fiber drawn from natural basalt. Basalt fiber is a new type of inorganic environmentally friendly green high-performance fiber material, which is composed of oxides such as silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, iron oxide and titanium dioxide. Basalt continuous fiber not only has high strength, but also has many excellent properties such as electrical insulation, corrosion resistance, and high temperature resistance.

[0054] Specifically, the length of the short-cut fibers is 1 to 15 mm. Further, the size of the basalt fibers is 10 to 15 mm.

[0055] The dispersant includes at least one of stearamide, sodium dodecylbenzene sulfonate, and polyvinyl pyrrolidone. That is, the dispersant can be any one of the above, or any two, any three, etc., and is selected according to actual needs. Preferably, the dispersant is stearamide.

[0056] The antioxidant includes at least one of antioxidant 1010, antioxidant 168, and antioxidant 626. That is, the antioxidant can be any one of the above, or any two, any three, etc., and is selected according to actual needs.

[0057] Among them, antioxidant 1010 is pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, antioxidant 168 is tris[2,4-di-tert-butylphenyl]phosphite, and antioxidant 626 is bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite.

[0058] In the polyamide composite material, the basalt fiber itself has excellent wave transmission and absorption properties. The network path formed by it forms a good guidance and segmentation for electromagnetic waves. The electromagnetic waves that have been transmitted and absorbed are quickly propagated with the help of the fiber network. After secondary absorption by the modified inorganic conductive material and modified magnetic material of the absorbing filler, the electromagnetic signal is converted into heat energy, thereby improving the reflection loss effect. In addition, the modified inorganic conductive material and the modified magnetic material also have amide groups, so the modified inorganic conductive material and the modified magnetic material have a lubricating effect. On the one hand, they can penetrate between the basalt fiber and the absorbing filler, which can achieve a good dispersion effect and improve the agglomeration effect between particles; on the other hand, they help to reduce the friction between the molecular chains during the injection molding process, thereby avoiding the shedding of the modified layer caused by the friction of the molecular chains. At the same time, due to the excellent particle dispersion effect between the absorbing filler and the basalt fiber, a tiny crystal nucleus is formed, which optimizes the crystallization effect of polyamide 6, produces a fine crystal strengthening effect, and significantly improves the mechanical properties of the material and reduces shrinkage.

[0059] See also Figure 2 The present invention also provides a method for preparing a polyamide composite material, comprising the following steps:

[0060] S21. According to weight percentage, weigh 61-76% of polyamide 6, 2-5% of absorbing filler, 20-30% of basalt fiber, 1-2% of dispersant and 1-2% of antioxidant, and mix them to obtain a premix; wherein the absorbing filler is the above-mentioned absorbing filler.

[0061] S22, placing the premix in a twin-screw extruder for melt plasticization, and then granulating to obtain masterbatch, the plasticization temperature is 280-300° C., and the rotation speed is 60-100 r / min.

[0062] S23, placing the masterbatch in a homogenizing furnace for homogenization.

[0063] S24, the homogenized masterbatch is dried at 80-90° C. for 3-4 hours to obtain a polyamide composite material.

[0064] The inventors of the present application have achieved the characteristics of the wave-absorbing filler and the polyamide composite material by strictly designing the content of each component. The content of each component is introduced through various embodiments below.

[0065] Embodiment 1

[0066] In terms of weight percentage, the polyamide composite material includes 61% polyamide 6, 5% wave absorbing filler, 30% basalt fiber, 2% dispersant and 2% antioxidant, wherein the length of the basalt fiber is 10 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0067] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 280° C., the rotation speed is 60 r / min, and the homogenized masterbatch is dried at 80° C. for 4 hours.

[0068] In terms of weight percentage, the wave-absorbing filler includes 35% of an inorganic conductive material, 55% of a magnetic material, and 10% of a modifier. The inorganic conductive material is graphite, the magnetic material is an iron-nickel alloy, and the modifier is PVP10. The preparation method of the wave-absorbing filler adopts the above preparation method, wherein the ultrasonic dispersion time of the modifier and the inorganic conductive material in an ethanol solvent is 20 minutes, and the dispersion temperature is 50°C, and the ultrasonic dispersion time of the modifier and the magnetic material in an ethanol solvent is 20 minutes, and the dispersion temperature is 50°C.

[0069] Embodiment 2

[0070] In terms of weight percentage, the polyamide composite material includes 76% polyamide 6, 2% wave absorbing filler, 20% basalt fiber, 1% dispersant and 1% antioxidant, wherein the length of the basalt fiber is 1 mm, the dispersant is sodium dodecylbenzene sulfonate, and the antioxidant is antioxidant 168.

[0071] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 300° C., the rotation speed is 100 r / min, and the homogenized masterbatch is dried at 90° C. for 3 hours.

[0072] In terms of weight percentage, the wave-absorbing filler includes 40% of an inorganic conductive material, 35% of a magnetic material, and 25% of a modifier. The inorganic conductive material is silicon carbide, the magnetic material is iron powder, and the modifier is polyacrylamide. The preparation method of the wave-absorbing filler adopts the above preparation method, wherein the ultrasonic dispersion time of the modifier and the inorganic conductive material in an ethanol solvent is 30 minutes, and the dispersion temperature is 30°C, and the ultrasonic dispersion time of the modifier and the magnetic material in an ethanol solvent is 30 minutes, and the dispersion temperature is 30°C.

[0073] Embodiment 3

[0074] The polyamide composite material includes 70% polyamide 6, 3% wave absorbing filler, 25% basalt fiber, 1% dispersant and 1% antioxidant by weight percentage, wherein the length of the basalt fiber is 15 mm, the dispersant is polyvinyl pyrrolidone, and the antioxidant is antioxidant 626.

[0075] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 285° C., the rotation speed is 70 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0076] In terms of weight percentage, the wave-absorbing filler includes 35% of an inorganic conductive material, 35% of a magnetic material, and 30% of a modifier. The inorganic conductive material is carbon fiber, the magnetic material is ferrite, and the modifier is KH550. The preparation method of the wave-absorbing filler adopts the above preparation method, wherein the ultrasonic dispersion time of the modifier and the inorganic conductive material in an ethanol solvent is 25 minutes, and the dispersion temperature is 40°C, and the ultrasonic dispersion time of the modifier and the magnetic material in an ethanol solvent is 20 minutes, and the dispersion temperature is 50°C.

[0077] Embodiment 4

[0078] In terms of weight percentage, the polyamide composite material includes 65% polyamide 6, 5% wave absorbing filler, 27% basalt fiber, 1.5% dispersant and 1.5% antioxidant, wherein the length of the basalt fiber is 8 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0079] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0080] In terms of weight percentage, the wave-absorbing filler includes 37% of inorganic conductive material, 48% of magnetic material and 15% of modifier. The inorganic conductive material is graphite, the magnetic material is iron-nickel alloy, and the modifier is PVP10. The preparation method of the wave-absorbing filler adopts the above preparation method, wherein the ultrasonic dispersion time of the modifier and the inorganic conductive material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C, and the ultrasonic dispersion time of the modifier and the magnetic material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C.

[0081] Embodiment 5

[0082] In terms of weight percentage, the polyamide composite material includes 65% polyamide 6, 5% wave absorbing filler, 27% basalt fiber, 1.5% dispersant and 1.5% antioxidant, wherein the length of the basalt fiber is 8 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0083] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0084] In terms of weight percentage, the wave absorbing filler includes 38% of inorganic conductive material, 42% of magnetic material and 20% of modifier. The inorganic conductive material is graphite, the magnetic material is iron-nickel alloy, and the modifier is PVP10. The ultrasonic dispersion time of the modifier and the inorganic conductive material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C. The ultrasonic dispersion time of the modifier and the magnetic material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C.

[0085] Embodiment 6

[0086] In terms of weight percentage, the polyamide composite material includes 65% polyamide 6, 5% wave absorbing filler, 27% basalt fiber, 1.5% dispersant and 1.5% antioxidant, wherein the length of the basalt fiber is 8 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0087] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0088] In terms of weight percentage, the wave absorbing filler includes 40% of inorganic conductive material, 50% of magnetic material and 10% of modifier. The inorganic conductive material is graphite, the magnetic material is iron-nickel alloy, and the modifier is PVP10. The ultrasonic dispersion time of the modifier and the inorganic conductive material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C. The ultrasonic dispersion time of the modifier and the magnetic material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C.

[0089] Embodiment 7

[0090] In terms of weight percentage, the polyamide composite material includes 70% polyamide 6, 2% wave absorbing filler, 26% basalt fiber, 1% dispersant and 1% antioxidant, wherein the length of the basalt fiber is 8 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0091] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0092] In terms of weight percentage, the wave absorbing filler includes 38% of inorganic conductive material, 42% of magnetic material and 20% of modifier. The inorganic conductive material is graphite, the magnetic material is iron-nickel alloy, and the modifier is PVP10. The ultrasonic dispersion time of the modifier and the inorganic conductive material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C. The ultrasonic dispersion time of the modifier and the magnetic material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C.

[0093] Comparative Example 1

[0094] The polyamide composite material includes 78% polyamide 6, 20% basalt fiber, 1% dispersant and 1% antioxidant by weight, wherein the length of the basalt fiber is 8 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0095] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0096] Comparative Example 2

[0097] In terms of weight percentage, the polyamide composite material includes 65% polyamide 6, 5% wave absorbing filler, 27% basalt fiber, 1.5% dispersant and 1.5% antioxidant, wherein the length of the basalt fiber is 8 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0098] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0099] In terms of weight percentage, the wave absorbing filler includes 45% of inorganic conductive material and 55% of magnetic material. The inorganic conductive material is graphite, and the magnetic material is iron-nickel alloy. The wave absorbing filler is obtained by uniformly mixing the inorganic conductive material and the magnetic material.

[0100] Comparative Example 3

[0101] In terms of weight percentage, the polyamide composite material includes 88% polyamide 6, 10% wave absorbing filler, 1% dispersant and 1% antioxidant, wherein the dispersant is stearamide and the antioxidant is antioxidant 1010.

[0102] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0103] In terms of weight percentage, the wave absorbing filler includes 40% of inorganic conductive material, 50% of magnetic material and 10% of modifier. The inorganic conductive material is graphite, the magnetic material is iron-nickel alloy, and the modifier is PVP10. The ultrasonic dispersion time of the modifier and the inorganic conductive material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C. The ultrasonic dispersion time of the modifier and the magnetic material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C.

[0104] Comparative Example 4

[0105] In terms of weight percentage, the polyamide composite material includes 65% polyamide 6, 5% wave absorbing filler, 27% glass fiber, 1.5% dispersant and 1.5% antioxidant, wherein the length of the glass fiber is 8 mm, the dispersant is stearamide, and the antioxidant is antioxidant 1010.

[0106] The preparation method of the polyamide composite material adopts the above preparation method, wherein the plasticizing temperature is 290° C., the rotation speed is 80 r / min, and the homogenized masterbatch is dried at 85° C. for 3.5 hours.

[0107] In terms of weight percentage, the wave absorbing filler includes 40% of inorganic conductive material, 50% of magnetic material and 10% of modifier. The inorganic conductive material is graphite, the magnetic material is iron-nickel alloy, and the modifier is PVP10. The ultrasonic dispersion time of the modifier and the inorganic conductive material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C. The ultrasonic dispersion time of the modifier and the magnetic material in the ethanol solvent is 25 minutes, and the dispersion temperature is 40°C.

[0108] The performance tests were conducted on the polyamide composite materials of Examples 1 to 7 and the polyamide composite materials of Comparative Examples 1 to 4, and the performances are shown in Table 1.

[0109] Among them, the tensile strength is tested according to the test standard GB / T 1040.2, the shrinkage is tested according to the test standard ASTM D955, and the reflection loss is tested as follows: a vector network analyzer is used to measure the S parameters of the sample and convert them into complex dielectric constant and complex magnetic permeability, and then the transmission line theory is used to calculate the reflection loss of the sample.

[0110] Table 1 Properties of polyamide composites

[0111]

[0112] It can be seen from the above table that the tensile strength of the polyamide composite materials in Examples 1 to 7 is ≥150 MPa, that is, it has high strength. The shrinkage rate of the polyamide composite materials in Examples 1 to 7 is ≤0.4%, and the reflection loss is ≥-12 dB.

[0113] By comparing the embodiments with comparative examples 1 and 2, it can be seen that after adding the absorbing filler, the modified absorbing filler fully exerts the absorbing effect, that is, the absorbing performance of the material is significantly improved after adding the absorbing filler in the present application.

[0114] By comparing the embodiments with comparative examples 3 and 4, it can be seen that the modified basalt fiber absorbing filler fully exerts the absorbing effect, that is, the absorbing performance of the material is significantly improved after adding the absorbing filler in the present application.

[0115] It can be seen from the above technical solution that the advantages and positive effects of the present invention are:

[0116] In the wave absorbing filler of the present invention, the surface of the modified inorganic conductive material is a modifier, and the surface of the modified magnetic material is a modifier, so basically no agglomeration will occur between the two, or between the two and other substances.

[0117] In the polyamide composite material of the present invention, the basalt fiber itself has excellent wave transmission and wave absorption properties. The network path formed by the basalt fiber can guide and divide the electromagnetic waves well. The electromagnetic waves that have been transmitted and absorbed are rapidly propagated with the help of the fiber network. After secondary absorption by the modified inorganic conductive material and the modified magnetic material of the wave-absorbing filler, the electromagnetic signals are converted into heat energy, thereby improving the reflection loss effect.

[0118] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A wave absorbing filler, It is characterized in that In terms of weight percentage, the wave absorbing filler comprises 35-40% of inorganic conductive material, 35-55% of magnetic material and 5-30% of modifier; The inorganic conductive material is conductive, the magnetic material is magnetic, the modifier has an amide functional group, the dispersant is coated on the inorganic conductive material to form a modified inorganic conductive material, and the dispersant is coated on the magnetic material to form a modified magnetic material.

2. The wave absorbing filler according to claim 1, It is characterized in that The inorganic conductive material includes at least one of graphite, silicon carbide or carbon fiber.

3. The wave absorbing filler according to claim 1, It is characterized in that The magnetic material includes at least one of an iron-nickel alloy, iron powder and ferrite.

4. The wave absorbing filler according to claim 1, It is characterized in that The modifier includes at least one of PVP10, polyacrylamide and KH550.

5. A method for preparing a wave-absorbing filler, It is characterized in that The following steps are involved: In terms of weight percentage, 35-40% of an inorganic conductive material, 35-55% of a magnetic material and 5-30% of a modifier are weighed; The modifier is mixed with the inorganic conductive material and ultrasonically dispersed in an ethanol solvent for 20 to 30 minutes at a dispersion temperature of 30°C to 50°C to obtain a modified inorganic conductive material; the modifier is mixed with the magnetic material and ultrasonically dispersed in an ethanol solvent for 20 to 30 minutes at a dispersion temperature of 30°C to 50°C to obtain a modified magnetic material; the modified inorganic conductive material and the modified magnetic material are uniformly mixed to obtain a third mixture; The third mixture is filtered and dried to obtain the wave absorbing filler.

6. A polyamide composite material, It is characterized in that The polyamide composite material comprises, by weight percentage, 61-76% of polyamide 6, 2-5% of wave-absorbing filler, 20-30% of basalt fiber, 1-2% of dispersant and 1-2% of antioxidant; Wherein, the absorbing filler is the absorbing filler described in any one of claims 1 to 4 or the absorbing filler prepared according to claim 5.

7. The polyamide composite material according to claim 6, It is characterized in that The melt index of the polyamide 6 is in the range of 15 to 30 g / min.

8. The polyamide composite material according to claim 6, It is characterized in that The length of the basalt fiber is 1 to 15 mm; and / or, The length of the basalt fiber is 10 to 25 mm.

9. The polyamide composite material according to claim 6, It is characterized in that The dispersant includes at least one of stearamide, sodium dodecylbenzene sulfonate, and polyvinyl pyrrolidone; The antioxidant includes at least one of antioxidant 1010 , antioxidant 168 , and antioxidant 626 .

10. A method for preparing a polyamide composite material, It is characterized in that The following steps are involved: According to weight percentage, 61-76% of polyamide 6, 2-5% of absorbing filler, 20-30% of basalt fiber, 1-2% of dispersant and 1-2% of antioxidant are weighed and mixed to obtain a premix; wherein the absorbing filler is the absorbing filler according to any one of claims 1 to 4 or the absorbing filler prepared according to claim 5; The premix is ​​placed in a twin-screw extruder for melt plasticization, and then granulated to obtain a masterbatch, the plasticization temperature is 280-300° C., and the rotation speed is 60-100 r / min; placing the masterbatch in a homogenizing furnace for homogenization; The homogenized masterbatch is dried at 80-90° C. for 3-4 hours to obtain the polyamide composite material.

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