CN111454546B - Electromagnetic shielding composite material and preparation method thereof - Google Patents
Electromagnetic shielding composite material and preparation method thereof Download PDFInfo
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- CN111454546B CN111454546B CN202010339384.5A CN202010339384A CN111454546B CN 111454546 B CN111454546 B CN 111454546B CN 202010339384 A CN202010339384 A CN 202010339384A CN 111454546 B CN111454546 B CN 111454546B
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- H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
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Abstract
The application relates to an electromagnetic shielding composite material and a preparation method thereof, wherein the electromagnetic shielding composite material comprises the following components in parts by weight: 100 parts of matrix resin, 15-20 parts of metal-plated carbon fibers, 10-12 parts of FeSiAl alloy powder, 6-8 parts of silver-plated carbon nanotubes, 3-5 parts of a toughening agent, 0.3-0.6 part of a coupling agent, 0.5-1 part of a compound antioxidant and 0.2-0.3 part of a lubricant; the electromagnetic shielding composite material provided by the invention has high electromagnetic shielding effect, and can keep the high strength of the composite material molding part. The preparation method provided can increase the combination of the metal-plated carbon fibers and FeSiAl alloy powder with matrix resin, weaken the catalytic aging of various metal components in a material system on a plastic matrix, effectively avoid the excessive crushing of the carbon fibers in the mixing process of an extruder and ensure the good mixing of all the components.
Description
Technical Field
The application belongs to the technical field of composite materials, and particularly relates to an electromagnetic shielding composite material and a preparation method thereof.
Background
With the development of modern science and technology and electronic industry, more and more electronic products enter our lives, bring great convenience to our lives and bring invisible and inaudible pollution, namely electromagnetic pollution. The electromagnetic interference generated by the electromagnetic radiation not only easily affects the performance of electronic products, but also affects communication, causes instrument failure and the like; electromagnetic pollution from electromagnetic radiation can also cause diseases in humans and other organisms. Electromagnetic protection is performed on communication equipment in many national defense fields, and proper electromagnetic protection is also required for some important monitoring equipment and research laboratories.
Electromagnetic shielding materials have also been increasingly moving from the early surface-coated type to composite materials capable of forming stressed structures. Most of the studies on electromagnetic shielding materials are mainly to mix materials having electromagnetic shielding effects with some adhesive materials or rubber materials. This is not favorable to the rapid shaping of the product, and is difficult to meet for the product which needs to be matched with the complex structural design and has the thermodynamic performance requirement subsequently. The electromagnetic shielding material using thermoplastic material as base material is only prepared by simple filling and mixing process, and the shielding effectiveness of the material is difficult to satisfy. Electromagnetic shielding materials that have high shielding effectiveness, wide shielding frequency range, and that can be stably mass-produced and molded are in major demand.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the electromagnetic shielding composite material has the advantages that the defects that an electromagnetic shielding material in the prior art is poor in shielding effect and low in tensile strength and is difficult to meet complex forming and the like are overcome, so that the electromagnetic shielding composite material can be stably produced and is convenient for product forming, has higher shielding efficiency and mechanical strength, and meets the requirements of various forming modes such as injection molding, extrusion and 3D printing on the electromagnetic shielding material.
The invention particularly provides an electromagnetic shielding composite material, wherein the electromagnetic shielding composite material comprises the following components in parts by weight:
100 parts of matrix resin, 15-20 parts of metal-plated carbon fibers, 10-12 parts of FeSiAl alloy powder, 6-8 parts of silver-plated carbon nanotubes, 3-5 parts of a toughening agent, 0.3-0.6 part of a coupling agent, 0.5-1 part of a compound antioxidant and 0.2-0.3 part of a lubricant;
wherein the compound antioxidant is a mixture consisting of hindered phenol antioxidant, phosphite antioxidant and metal ion passivator.
Preferably, the matrix resin is PA11, PA12, or PETG resin.
Furthermore, the metal-plated carbon fibers are chopped carbon fibers with copper plated inner layers and nickel plated outer layers, and the length of the chopped carbon fibers is 4-6 mm.
Further, the particle size of the FeSiAl alloy powder is 30-100 mu m, wherein the content of Si is 10-12%, and the content of Al is 5-8%.
Further, the toughening agent is a maleic anhydride grafted ethylene-octene copolymer or an ethylene-acrylate-maleic anhydride copolymer.
Further, the coupling agent is a silane coupling agent or a titanate coupling agent;
preferably, the coupling agent is a coupling agent KH-550, a coupling agent KH-560 or a coupling agent KR-TTS.
More preferably, wherein 2/3 total weight of coupling agent is used to prepare the coupling agent modified metallized carbon fiber and 1/3 total weight of coupling agent is used to prepare the coupling agent modified fesai alloy powder.
Further, the compound antioxidant comprises 40-60 wt% of hindered phenol antioxidant, 20-30 wt% of phosphite antioxidant and the balance of metal ion passivator;
wherein the hindered phenol antioxidant is antioxidant 1010, antioxidant 1076 or antioxidant 330; the phosphite antioxidant is antioxidant 168, antioxidant P-EPQ or antioxidant TNPP; the metal ion passivator is an antioxidant 1024 or an antioxidant 697.
Further, the lubricant is N, N' -ethylene bis stearamide, magnesium stearate or pentaerythritol stearate.
The invention also provides a preparation method of the electromagnetic shielding composite material, which comprises the following steps:
(1) pre-drying the matrix resin until the moisture content is not more than 0.05%;
(2) mixing the silver-plated carbon nano tube, the compounded antioxidant and 20-30% of matrix resin in the total amount dried in the step (1) to obtain a premix;
(3) putting the premix prepared in the step (2) into a continuous internal mixer, plasticating, extruding, granulating and drying to obtain master batch A1;
(4) preparing a coupling agent solution: adding a coupling agent into ethanol or water to prepare a coupling agent solution with the mass concentration of 10-20%, and adjusting the pH value of the coupling agent solution to 4-5.5;
(5) preparing coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder: respectively spraying atomized coupling agent solution into the metal-plated carbon fibers and FeSiAl alloy powder under stirring at the speed of 100-200 r/min, continuously stirring for 1-10 minutes after the coupling agent solution is sprayed, then drying the obtained metal-plated carbon fibers and FeSiAl alloy powder with the surfaces being soaked with the coupling agent at the temperature of 90-100 ℃ for 2-3 hours, and cooling to normal temperature to obtain coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder;
(6) premixing a toughening agent, a lubricant and the rest of matrix resin in a stirrer to obtain a premix A2;
(7) premixing the master batch A1 and coupling agent modified FeSiAl alloy powder to obtain a premix A3;
(8) adding the pre-mixture A2 from a main feed inlet of a double-screw extruder, and respectively adding the pre-mixture A3 and the coupling agent modified metal-plated carbon fiber from two different side feed inlets of the double-screw extruder;
(9) and extruding the melt, granulating and drying to obtain the electromagnetic shielding composite material.
In the method, preferably, in the step (2), the silver-plated carbon nanotubes, the compounded antioxidant and 20-30% of the matrix resin dried in the step (1) are mixed in a mixer at a speed of 100-300 r/min for 5-10 minutes to obtain a premix;
and (3) putting the premix prepared in the step (2) into a continuous internal mixer, plasticating at 210-220 ℃, extruding for granulation, and drying to obtain master batch A1.
Further preferably, the method for preparing the coupling agent modified metallized carbon fiber and the coupling agent modified fesai alloy powder in the step (5), wherein the amount of the coupling agent used for preparing the coupling agent modified metallized carbon fiber is 2/3 based on the total weight, and the amount of the coupling agent used for preparing the coupling agent modified fesai alloy powder is 1/3 based on the total weight.
Further preferably, 10-11 heating sections are selected for the double-screw extruder in the step (8), wherein the temperature of the first heating section is 185-200 ℃, the temperature of the other sections is 210-230 ℃, when the double-screw extruder is heated to the set temperature, the premix A3 is added from a feeding port on the side of the zone 4-6 of the double-screw extruder, and the coupling agent modified metal-plated carbon fiber is added from a feeding port on the side of the zone 7-8 of the double-screw extruder.
Further preferably, the melt extruded in the step (9) is dried in a dehumidification dryer at 110-120 ℃ for about 4 hours after being cooled in water, dried in air and cut into particles, so as to obtain the electromagnetic shielding composite material.
In another more preferred embodiment of the present invention, there is provided a method for preparing the electromagnetic shielding composite, comprising the steps of:
(1) pre-drying the matrix resin until the moisture content is not more than 0.05%;
(2) mixing the silver-plated carbon nano tube, the compounded antioxidant and 20-30% of matrix resin prepared in the step (1), preferably 20% of matrix resin in the total amount at 100-300 r/min in a mixer for 5-10 minutes to obtain a premix;
(3) putting the premix prepared in the step (2) into a continuous internal mixer, plasticating at 210-220 ℃, extruding for granulation, and drying to obtain master batch A1;
(4) preparing a coupling agent solution: adding a coupling agent into ethanol or water to prepare a coupling agent solution with the mass concentration of 10-20%, and adjusting the pH value of the coupling agent solution to 4-5.5;
(5) preparing coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder: respectively spraying atomized 2/3 total weight coupling agent solution and 1/3 total weight coupling agent solution into the metal-plated carbon fiber and FeSiAl alloy powder under stirring at the speed of 100-200 r/min, and continuously stirring for 1-10 minutes, preferably 5 minutes after the coupling agent solution is sprayed;
then, drying the obtained metal-plated carbon fibers with the surface soaked with the coupling agent and FeSiAl alloy powder at 90-100 ℃ for 2-3 hours, cooling to normal temperature, and separately storing to obtain coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder;
(6) premixing a toughening agent, a lubricant and the rest of matrix resin in a stirrer to obtain a premix A2;
(7) premixing the master batch A1 and coupling agent modified FeSiAl alloy powder to obtain a premix A3;
(8) selecting 10-11 heating sections for the double-screw extruder, wherein the first heating section is 185-200 ℃, the other sections are 210-230 ℃, when the double-screw extruder is heated to the set temperature, the premix A3 is added from a side feed inlet of the double-screw extruder at the 4-6 section, and the coupling agent modified metal-plated carbon fiber is added from a side feed inlet of the double-screw extruder at the 7-8 section;
(9) and extruding the melt for granulation to obtain the electromagnetic shielding composite material, and specifically, drying the extruded melt for 3-4 hours at 110-120 ℃ in a dehumidification dryer after water cooling, air drying and grain cutting are carried out on the extruded melt to obtain the electromagnetic shielding composite material.
The obtained electromagnetic shielding composite material can be used for injection molding or an industrial 3D printer using granules to form a required electromagnetic shielding part.
The invention has the beneficial effects that:
the invention can increase the strength of the material and the conductivity of the carbon fiber by adopting the metal-plated carbon fiber, particularly when the metal-plated carbon fiber is the chopped carbon fiber with copper plated on the inner layer and nickel plated on the outer layer, the copper plated layer can increase the conductivity, the nickel plated layer has the anti-oxidation effect, and the hysteresis loss of the composite material to electromagnetic waves is increased.
The FeSiAl alloy powder is beneficial to the magnetic loss of the composite material when the particle size of the FeSiAl alloy powder is 30-100 mu m, wherein the content of Si is 10-12% and the content of Al is 5-8%.
The carbon nano tube is a conductive nano material, the silver-plated carbon nano tube increases the conductivity, reduces the agglomeration of the carbon nano tube and can form a conductive network with other two conductive materials in a system; the master batch is firstly produced in a continuous internal mixer by the matrix resin with the total amount of 20-30 percent, so that the problem that the carbon nano tube is not easy to disperse in a plastic matrix can be effectively solved.
In the electromagnetic shielding composite material provided by the invention, a compound antioxidant system is adopted, the catalytic aging of various metal components in the material system on a plastic matrix can be effectively weakened, three antioxidants can respectively play roles in capturing free radicals, decomposing hydroperoxides and capturing metal ions, and the three antioxidants are compounded for use and can take effect at each stage of matrix resin oxidation of the material system.
The maleic anhydride copolymer serving as a toughening agent can be well compatible with the matrix resin, the flexibility of the composite material is improved, the possible interruption of the material strip in production is reduced, and the defect that a material system filled with more fibers and metal powder is brittle is overcome.
Aiming at the problem that the shielding effectiveness of the material is difficult to meet only through a simple filling and mixing process in the prior art, the invention provides a novel preparation method of the electromagnetic shielding composite material by optimizing the feeding mode and the process conditions, and particularly, the silver-plated carbon nanotube master batch is prepared in step (3), and the premix and the metal-plated carbon fiber are added from two different side feeding ports in step (8), so that the uniform mixing of the material can be ensured, and the excessive crushing of the carbon fiber in the mixing process of an extruder can be effectively avoided.
And (5) plating metal carbon fibers and FeSiAl alloy powder which contain more metal components, and pre-treating the components by using a coupling agent to increase the combination of the two components and matrix resin.
The electromagnetic shielding composite material prepared by the method provided by the invention has a high electromagnetic shielding effect, can keep the high strength of the composite material forming part, and meanwhile, has good reproducibility and can be stably produced and applied.
The electromagnetic shielding composite material provided by the invention can meet the requirements of various molding modes such as injection molding, extrusion, 3D printing and the like on the electromagnetic shielding material.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
Unless otherwise specified, "content" in the present invention means weight percentage; terms used in the present invention are understood in the conventional sense in the art unless otherwise specifically explained. The product or raw material can be obtained from market.
The metal-plated carbon fibers used in the following examples are short carbon fibers with copper plated inner layers and nickel plated outer layers, and the length of the short carbon fibers is 4-6 mm; the FeSiAl alloy powder has a particle size of 30-100 μm, wherein the content of Si in the silicon element is 10-12%, and the content of Al in the aluminum element is 5-8%.
Embodiment 1 an electromagnetic shielding composite material and a method for preparing the same
An electromagnetic shielding composite material comprises the following components in percentage by weight:
100 parts of PETG resin, 18 parts of metal-plated carbon fiber, 10 parts of FeSiAl alloy powder, 8 parts of silver-plated carbon nano tube, 5 parts of toughening agent maleic anhydride grafted ethylene-octene copolymer, 0.5 part of coupling agent KH-560, 0.5 part of compound antioxidant and 0.2 part of lubricant N, N' -ethylene bis stearamide.
Wherein the compound antioxidant is a mixture consisting of 40 weight percent of antioxidant 1010, 30 weight percent of antioxidant 168 and 30 weight percent of antioxidant 1024.
The preparation method comprises the following steps:
(1) predrying the PETG resin until the moisture content is not more than 0.05 percent before use;
(2) weighing silver-plated carbon nanotubes, a compound antioxidant and 20 parts of PETG resin according to the required weight, and mixing for 5 minutes at 200r/min in a mixer to obtain a premix;
(3) putting the obtained premix into a continuous internal mixer, plasticating at 215 ℃, extruding for granulation, and drying to obtain master batch A1;
(4) preparing a coupling agent solution with the mass concentration of 15% by using ethanol, and adjusting the pH value of the coupling agent solution to be 4-5.5;
(5) respectively stirring the metal-plated carbon fiber and FeSiAl alloy powder at the speed of 100r/min, simultaneously spraying atomized coupling agent solution, continuously stirring for 5 minutes after the coupling agent solution is sprayed, then drying the obtained metal-plated carbon fiber and FeSiAl alloy powder with the surface soaked with the coupling agent at the temperature of 100 ℃ for 2 hours, cooling to normal temperature, and separately storing to obtain coupling agent modified metal-plated carbon fiber and coupling agent modified FeSiAl alloy powder, wherein the dosage of the coupling agent for preparing the coupling agent modified metal-plated carbon fiber is 2/3 of the total weight, and the dosage of the coupling agent for preparing the coupling agent modified FeSiAl alloy powder is 1/3 of the total weight;
(6) respectively weighing coupling agent modified metal-plated carbon fibers, coupling agent modified FeSiAl alloy powder, a toughening agent, a lubricant and 80 parts of PETG resin;
the corresponding toughening agent, lubricant, 80 parts of PETG resin were premixed in a blender to give premix A2.
(7) Premixing the A1 and coupling agent modified FeSiAl alloy powder to obtain a premix A3;
(8) setting the temperature of the twin-screw extruder (11 heating sections are selected, wherein the first heating section is 185 ℃ and the other sections are 210-230 ℃), adding the premix A2 from the main feed inlet of the twin-screw extruder when the twin-screw extruder is heated to the set temperature, adding the premix A3 from the feed inlet 1 at the zone side of the twin-screw extruder 4, and adding the coupling agent modified metal-plated carbon fiber from the feed inlet 2 at the zone side of the twin-screw extruder 8;
(9) and (3) cooling the extruded melt by water, air-drying, granulating, drying at 110 ℃ for about 4 hours in a dehumidification dryer, cooling to normal temperature, and packaging in a bag for sealing and storing.
The obtained granules are the electromagnetic shielding composite material and can be used for injection molding or molding parts with the electromagnetic shielding function by using an industrial 3D printer of the granules.
Embodiment 2 an electromagnetic shielding composite material and a method for preparing the same
An electromagnetic shielding composite material comprises the following components in percentage by weight:
100 parts of PA12 resin, 15 parts of metal-plated carbon fiber, 12 parts of FeSiAl alloy powder, 8 parts of silver-plated carbon nano tube, 3 parts of toughening agent maleic anhydride grafted ethylene-octene copolymer, 0.3 part of coupling agent KR-TTS, 1 part of compound antioxidant and 0.2 part of lubricant magnesium stearate.
Wherein the compound antioxidant is a mixture consisting of 60 weight percent of antioxidant 330, 20 weight percent of antioxidant P-EPQ and 20 weight percent of antioxidant 697.
The preparation method comprises the following steps:
(1) pre-drying the resin until the water content is not more than 0.05 percent before use;
(2) weighing silver-plated carbon nanotubes, an antioxidant and 30 parts of PA12 resin by required weight, and mixing for 10 minutes at a speed of 100r/min in a mixer to obtain a premix;
(3) putting the premix obtained in the step (2) into a continuous internal mixer, plasticating at 210 ℃, extruding for granulation, and drying to obtain master batch A1;
(4) preparing a coupling agent solution: preparing a coupling agent solution with the mass concentration of 10% by using water, and adjusting the pH value of the coupling agent solution to be 4-5.5;
(5) respectively stirring the metal-plated carbon fibers and the FeSiAl alloy powder at the speed of 200r/min, simultaneously spraying atomized coupling agent solution, continuously stirring for 10 minutes after the coupling agent solution is sprayed, then drying the obtained metal-plated carbon fibers and the FeSiAl alloy powder with the surfaces soaked with the coupling agent at 90 ℃ for 3 hours, cooling to normal temperature, and separately storing to obtain coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder, wherein the dosage of the coupling agent for preparing the coupling agent modified metal-plated carbon fibers is 2/3 of the total weight, and the dosage of the coupling agent for preparing the coupling agent modified FeSiAl alloy powder is 1/3 of the total weight;
(6) respectively weighing coupling agent modified metal-plated carbon fibers, coupling agent modified FeSiAl alloy powder, a toughening agent, a lubricant and 70 parts of PA12 resin;
the corresponding toughening agent, lubricant, 70 parts of PA12 resin were premixed in a blender to give premix a 2.
(7) Premixing the A1 and coupling agent modified FeSiAl alloy powder to obtain a premix A3;
(8) when the temperature of the twin-screw extruder is raised to a set temperature (10 heating sections are selected, wherein the temperature of the first heating section is 200 ℃, and the temperature of the other sections is 210-230 ℃), the premix A2 is added from a main feed inlet of the twin-screw extruder, the premix A3 is added from a feed inlet 1 at the zone side of the twin-screw extruder 4, and the coupling agent modified metal-plated carbon fiber is added from a feed inlet 2 at the zone side of the twin-screw extruder 8.
(9) And (3) cooling the extruded melt by water, air-drying, granulating, drying in a dehumidifying dryer at 120 ℃ for about 4 hours, cooling to normal temperature, bagging, sealing and storing to obtain the product.
Embodiment 3 an electromagnetic shielding composite material and a method for preparing the same
The difference from the electromagnetic shielding composite material described in example 1 is the following composition (the composition is not described in example 1):
20 parts of metal-plated carbon fiber, 6 parts of silver-plated carbon nanotube, 4 parts of toughening agent, 0.6 part of coupling agent KH-560, 0.8 part of compound antioxidant and 0.3 part of lubricant pentaerythritol stearate.
An electromagnetically shielding composite material was prepared in a similar manner to that described in reference example 1 (the same steps and processes as in example 1 are not described).
Embodiment 4 an electromagnetic shielding composite material and a method for preparing the same
The difference from example 1 is the following composition (the composition and process not described is the same as example 1):
100 parts of PA11 resin, 11 parts of FeSiAl alloy powder, 7 parts of silver-plated carbon nano tube, 3 parts of toughening agent ethylene-acrylate-maleic anhydride copolymer, 0.4 part of coupling agent and 0.6 part of compound antioxidant.
Wherein the compound antioxidant is a mixture consisting of 40 weight percent of antioxidant 1076, 30 weight percent of antioxidant 168 and 30 weight percent of antioxidant 1024.
Embodiment 5 an electromagnetic shielding composite material and a method for preparing the same
The difference from example 1 is the following composition (the composition and process not described is the same as example 1):
100 parts of matrix resin, 15 parts of metal-plated carbon fiber, 12 parts of FeSiAl alloy powder and 0.8 part of compound antioxidant.
Wherein the compound antioxidant is a mixture consisting of 50 weight percent of antioxidant 1010, 20 weight percent of antioxidant 168 and 30 weight percent of antioxidant 697.
Comparative example 1 electromagnetic shielding composite material and method for preparing the same
The electromagnetic shielding composite material having the composition of example 1 was prepared according to the following method:
(1) pre-drying the resin until the water content is not more than 0.05 percent before use;
(2) weighing the components according to the proportion, premixing in a stirrer, and adding the premix directly from a main feeding port of the double-screw extruder when the double-screw extruder is heated to a set temperature (wherein the temperature of a first heating section is 185 ℃, and the temperature of other sections is 210-230 ℃). And (3) cooling the extruded melt by water, air-drying, granulating, drying at 115 ℃ for about 4 hours in a dehumidification dryer, cooling to normal temperature, and packaging in a bag for sealing and storing.
Comparative example 2: electromagnetic shielding composite material and preparation method thereof
An electromagnetic shielding composite material comprises the following components in percentage by weight:
100 parts of PETG resin, 18 parts of metal-plated carbon fiber, 18 parts of FeSiAl alloy powder, 5 parts of a toughening agent maleic anhydride grafted ethylene-octene copolymer, 0.5 part of a coupling agent KH-560, 0.7 part of a compound antioxidant and 0.2 part of lubricant N, N' -ethylene bis stearamide.
The preparation steps are as follows:
(1) the resin is pre-dried before use to a moisture content of no more than 0.05%.
(2) Preparing a coupling agent solution with the mass concentration of 15% by using water, and adjusting the pH value of the coupling agent solution to be 4-5.5;
(3) respectively stirring the metal-plated carbon fibers and the FeSiAl alloy powder at the speed of 100r/min, simultaneously spraying atomized coupling agent solution, continuously stirring for 5 minutes after the coupling agent solution is sprayed, then drying the obtained metal-plated carbon fibers and the FeSiAl alloy powder with the surfaces being soaked with the coupling agent at the temperature of 100 ℃ for 2 hours, cooling to normal temperature, and separately storing to obtain coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder;
(4) respectively weighing PETG resin, coupling agent modified metal-plated carbon fibers, coupling agent modified FeSiAl alloy powder, a toughening agent maleic anhydride grafted ethylene-octene copolymer and a lubricant.
And premixing the corresponding PETG resin, the toughening agent, the compounded antioxidant and the lubricant in a stirrer to obtain a premix.
(5) Setting the temperature of the double-screw extruder, selecting 11 heating sections, wherein the first heating section is set to be 190 ℃, the other sections are set to be 210-230 ℃, when the double-screw extruder is heated to the set temperature, adding the premix from a main feed inlet of the double-screw extruder, adding the coupling agent modified FeSiAl alloy powder from a feed inlet 1 at the zone 4 side of the double-screw extruder, and adding the coupling agent modified metal-plated carbon fiber from a feed inlet 2 at the zone 8 side of the double-screw extruder. And (3) cooling the extruded melt by water, air-drying, granulating, drying in a dehumidification dryer at 110 ℃ for about 4 hours, cooling to normal temperature, and then packaging in bags for sealed storage.
Comparative example 3: electromagnetic shielding composite material and preparation method thereof
The only difference from example 1 is that the formulated antioxidant of example 1 is replaced with antioxidant 168.
Comparative example 4: electromagnetic shielding composite material and preparation method thereof
The electromagnetic shielding composite material having the composition of example 1 was prepared according to the following method:
(1) pre-drying the resin until the water content is not more than 0.05 percent before use;
(2) preparing a coupling agent solution with the mass concentration of 15% by using ethanol, and adjusting the pH value of the coupling agent solution to be 4-5.5;
(3) respectively stirring the metal-plated carbon fiber and FeSiAl alloy powder at the speed of 100r/min, simultaneously spraying atomized coupling agent solution, continuously stirring for 5 minutes after the coupling agent solution is sprayed, then drying the obtained metal-plated carbon fiber and FeSiAl alloy powder with the surface soaked with the coupling agent at the temperature of 100 ℃ for 2 hours, cooling to normal temperature, and separately storing to obtain coupling agent modified metal-plated carbon fiber and coupling agent modified FeSiAl alloy powder, wherein the dosage of the coupling agent for preparing the coupling agent modified metal-plated carbon fiber is 2/3 of the total weight, and the dosage of the coupling agent for preparing the coupling agent modified FeSiAl alloy powder is 1/3 of the total weight;
(4) respectively weighing PETG resin, coupling agent modified metal-plated carbon fibers, coupling agent modified FeSiAl alloy powder, silver-plated carbon nanotubes, a toughening agent, a compound antioxidant and a lubricant;
and premixing the corresponding PETG resin, the silver-plated carbon nano tube, the toughening agent, the antioxidant and the lubricant in a stirrer to obtain a premix.
(5) Setting the temperature of the double-screw extruder, selecting 11 heating sections, wherein the first heating section is set to be 190 ℃, the other sections are set to be 210-230 ℃, when the temperature of the double-screw extruder is raised to the set temperature, adding the premix from a main feed inlet of the double-screw extruder, adding the coupling agent modified FeSiAl alloy powder from a feed inlet 1 at the zone 4 side of the double-screw extruder, and adding the coupling agent modified metal-plated carbon fiber from a feed inlet 2 at the zone 8 side of the double-screw extruder;
(9) and (3) cooling the extruded melt by water, air-drying, granulating, drying in a dehumidification dryer at 110 ℃ for about 4 hours, cooling to normal temperature, bagging, sealing and storing to obtain the product.
The samples obtained above were printed by an industrial 3D printer on 150mm by 2mm templates, and the shielding effectiveness of the test materials was tested according to standard GB/T12190-. The samples were printed and tested for tensile strength according to the A-type tensile spline of the GB/T1040-2006 standard. The results are given in the following table:
table 1: results of Performance testing
| Example number | Tensile Strength (MPa) | Electromagnetic shielding effectiveness (dB) |
| Example 1 | 82 | 76 |
| Example 2 | 80 | 73 |
| Example 3 | 83 | 75 |
| Example 4 | 82 | 75 |
| Example 5 | 78 | 72 |
| Comparative example 1 | 72 | 61 |
| Comparative example 2 | 78 | 69 |
| Comparative example 3 | 77 | 70 |
| Comparative example 4 | 75 | 72 |
From the test results of the electromagnetic shielding composite materials of the embodiments 1 to 5, it can be seen that the electromagnetic shielding composite materials prepared by the components and the method have good electromagnetic shielding effectiveness, stable production and high tensile strength of the parts.
In comparative example 1, the tensile strength and the shielding effectiveness of the composite material are greatly reduced because the metal-plated carbon fibers are seriously broken and the nano-particle silver-plated carbon nanotubes are not easy to disperse uniformly by simply premixing and then directly adding the premix from a double-screw extruder for extrusion granulation. Comparative example 2 without the addition of silver-plated carbon nanotubes and related processes, the tensile strength and electromagnetic shielding effectiveness of the fabricated article were also reduced. Comparative example 3 only the antioxidant 168 was added, since it was not effective in preventing oxidation of the metal components and degradation of the plastic matrix; comparative example 4 omits the process of preparing the mother pellets of silver-plated carbon nanotubes, and the silver-plated carbon nanotubes and the resin are directly fed from the main feeding port, so that the silver-plated carbon nanotubes are not well dispersed, and the results of comparative example 3 and comparative example 4 are also lowered as compared to example 1.
The 3D printing forming is very suitable for forming parts with various complex structures, but the strength of the 3D printing forming part is lower than that of the traditional forming part at present, the composite material of the scheme of injection molding or compression molding forming is used, and the tensile strength is 90-110 MPa.
In light of the foregoing description of the preferred embodiments of the present application, it is to be understood that various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present application is not limited to the contents of the specification, and must be determined according to the scope of the claims.
Claims (13)
1. The electromagnetic shielding composite material is characterized by comprising the following components in parts by weight:
100 parts of matrix resin, 15-20 parts of metal-plated carbon fibers, 10-12 parts of FeSiAl alloy powder, 6-8 parts of silver-plated carbon nanotubes, 3-5 parts of a toughening agent, 0.3-0.6 part of a coupling agent, 0.5-1 part of a compound antioxidant and 0.2-0.3 part of a lubricant;
the compound antioxidant is a mixture consisting of a hindered phenol antioxidant, a phosphite antioxidant and a metal ion passivator, and the metal-plated carbon fiber is chopped carbon fiber with an inner layer plated with copper and an outer layer plated with nickel;
the preparation method of the electromagnetic shielding composite material comprises the following steps:
(1) pre-drying the matrix resin until the moisture content is not more than 0.05%;
(2) mixing the silver-plated carbon nano tube, the compound antioxidant and 20-30% of matrix resin in the total amount prepared in the step (1) to obtain a premix;
(3) plasticating the premix prepared in the step (2), extruding, granulating and drying to obtain master batch A1;
(4) preparing a coupling agent solution: adding a coupling agent into ethanol or water to prepare a coupling agent solution with the mass concentration of 10-20%, and adjusting the pH value of the coupling agent solution to 4-5.5;
(5) preparing coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder: respectively spraying atomized coupling agent solution into the metal-plated carbon fibers and FeSiAl alloy powder under stirring at the speed of 100-200 r/min, continuously stirring for 1-10 minutes after the coupling agent solution is sprayed, then drying the obtained metal-plated carbon fibers and FeSiAl alloy powder with the surfaces being soaked with the coupling agent at the temperature of 90-100 ℃ for 2-3 hours, and cooling to normal temperature to obtain coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder;
(6) premixing a toughening agent, a lubricant and the rest of matrix resin in a stirrer to obtain a premix A2;
(7) premixing the master batch A1 and coupling agent modified FeSiAl alloy powder to obtain a premix A3;
(8) adding the pre-mixture A2 from a main feed inlet of a double-screw extruder, and respectively adding the pre-mixture A3 and the coupling agent modified metal-plated carbon fiber from two different side feed inlets of the double-screw extruder;
(9) and extruding the melt, granulating and drying to obtain the electromagnetic shielding composite material.
2. The electromagnetically shielding composite as claimed in claim 1, wherein said matrix resin is PA11, PA12 or PETG resin.
3. The electromagnetically shielding composite material as claimed in claim 1, wherein said metallized carbon fibers have a length of 4 to 6 mm.
4. The electromagnetic shielding composite material as claimed in claim 1, wherein the FeSiAl alloy powder has a particle size of 30-100 μm, wherein Si is 10-12% and Al is 5-8%.
5. The electromagnetic shielding composite of claim 1, wherein the toughening agent is a maleic anhydride grafted ethylene-octene copolymer or an ethylene-acrylate-maleic anhydride copolymer.
6. The electromagnetic shielding composite of claim 1, wherein the coupling agent is a silane coupling agent or a titanate coupling agent.
7. The electromagnetic shielding composite of claim 6, wherein the coupling agent is KH-550, KH-560 or KR-TTS.
8. The electromagnetic shielding composite material according to claim 1, wherein the compounded antioxidant comprises 40-60 wt% of hindered phenol antioxidant, 20-30 wt% of phosphite antioxidant, and the balance of metal ion passivator; the hindered phenol antioxidant is antioxidant 1010, antioxidant 1076 or antioxidant 330; the phosphite antioxidant is antioxidant 168, antioxidant P-EPQ or antioxidant TNPP; the metal ion passivator is an antioxidant 1024 or an antioxidant 697.
9. The electro-magnetic shielding composite of claim 1, wherein the lubricant is N, N' -ethylene bis stearamide, magnesium stearate, or pentaerythritol stearate.
10. A method for preparing an electromagnetic shielding composite material as claimed in any one of claims 1 to 9, comprising the steps of:
(1) pre-drying the matrix resin until the moisture content is not more than 0.05%;
(2) mixing the silver-plated carbon nano tube, the compound antioxidant and 20-30% of matrix resin in the total amount prepared in the step (1) to obtain a premix;
(3) putting the premix prepared in the step (2) into a continuous internal mixer, plasticating, extruding, granulating and drying to obtain master batch A1;
(4) preparing a coupling agent solution: adding a coupling agent into ethanol or water to prepare a coupling agent solution with the mass concentration of 10-20%, and adjusting the pH value of the coupling agent solution to 4-5.5;
(5) preparing coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder: respectively spraying atomized coupling agent solution into the metal-plated carbon fibers and FeSiAl alloy powder under stirring at the speed of 100-200 r/min, continuously stirring for 1-10 minutes after the coupling agent solution is sprayed, then drying the obtained metal-plated carbon fibers and FeSiAl alloy powder with the surfaces being soaked with the coupling agent at the temperature of 90-100 ℃ for 2-3 hours, and cooling to normal temperature to obtain coupling agent modified metal-plated carbon fibers and coupling agent modified FeSiAl alloy powder;
(6) premixing a toughening agent, a lubricant and the rest of matrix resin in a stirrer to obtain a premix A2;
(7) premixing the master batch A1 and coupling agent modified FeSiAl alloy powder to obtain a premix A3;
(8) adding the pre-mixture A2 from a main feed inlet of a double-screw extruder, and respectively adding the pre-mixture A3 and the coupling agent modified metal-plated carbon fiber from two different side feed inlets of the double-screw extruder;
(9) and extruding the melt, granulating and drying to obtain the electromagnetic shielding composite material.
11. The method of claim 10,
step (2) mixing the silver-plated carbon nano tube, the compounded antioxidant and 20-30% of matrix resin in the total amount dried in the step (1) in a mixer at a speed of 100-300 r/min for 5-10 minutes to obtain a premix;
and (3) putting the premix prepared in the step (2) into a continuous internal mixer, plasticating at 210-220 ℃, extruding for granulation, and drying to obtain master batch A1.
12. The method of claim 10, wherein the coupling agent modified metallized carbon fibers and the coupling agent modified fesai alloy powder are prepared in step (5), wherein the amount of the coupling agent used to prepare the coupling agent modified metallized carbon fibers is 2/3 based on the total weight, and the amount of the coupling agent used to prepare the coupling agent modified fesai alloy powder is 1/3 based on the total weight.
13. The method according to claim 10, wherein the twin-screw extruder in the step (8) selects 10 to 11 heating sections, wherein the first heating section is 185 to 200 ℃, the other heating sections are 210 to 230 ℃, when the twin-screw extruder is raised to the set temperature, the premix A3 is added from a side feed port of the twin-screw extruder from 4 to 6 zones, and the coupling agent modified metal-plated carbon fiber is added from a side feed port of the twin-screw extruder from 7 to 8 zones.
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| CN112876836A (en) * | 2021-01-18 | 2021-06-01 | 浙江理工大学 | High-performance electromagnetic shielding carbon fiber composite material |
| CN113004552A (en) * | 2021-03-17 | 2021-06-22 | 连云港鹰游纺机集团有限公司 | Carbon fiber reinforced composite material with electromagnetic shielding function and preparation method thereof |
| CN113185799A (en) * | 2021-04-28 | 2021-07-30 | 衢州艾科科技有限公司 | Composite material with electromagnetic shielding function and preparation method thereof |
| CN113621222A (en) * | 2021-08-13 | 2021-11-09 | 江阴市龙山合成材料有限公司 | Low-melting-point PBT electromagnetic shielding composite material and preparation method thereof |
| CN113943454A (en) * | 2021-09-16 | 2022-01-18 | 江苏上上电缆集团新材料有限公司 | Graphene and carbon nanotube synergistic high-electrical-property semiconductive shielding material and preparation method thereof |
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