Electromagnetic shielding wave-absorbing coating with good corrosion resistance and preparation method thereof

Abstract

The invention provides an electromagnetic shielding wave-absorbing coating with good corrosion resistance and a preparation method thereof. The electromagnetic shielding wave-absorbing coating is prepared from the following raw materials in percentage by weight: polyurethane modified epoxy resin, polyethersulfone resin, silver-coated copper powder, graphene, zinc powder, polypyrrole, an anticorrosive agent, a coupling agent, an antioxidant, an anti-settling agent and a dispersing agent. The polyurethane modified epoxy resin and the polyethersulfone resin are mixed to serve as a synthetic resin matrix, the high temperature resistance and the chemical corrosion resistance of the coating can be enhanced, then graphene and zinc powder are added for cooperation, the corrosion resistance is enhanced while the conductivity is guaranteed, and finally the anticorrosive agent and the antioxidant serve as auxiliaries, so that the corrosion resistance of the coating is improved. In addition, on the aspect of electrical conductivity, silver-coated copper powder and polypyrrole are introduced to be matched, good electrical conductivity is achieved, and therefore the corrosion resistance of the electromagnetic shielding wave-absorbing coating is improved while the performance of the electromagnetic shielding wave-absorbing coating is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of absorbing coatings, and in particular to an electromagnetic shielding absorbing coating with good corrosion resistance and a preparation method thereof. Background Art

[0002] Absorbing material is a material that can be used to absorb or greatly weaken the electromagnetic wave energy received on its surface, thereby reducing electromagnetic radiation or interference, while coating is a viscous liquid with a main resin or other gelling material as the base material, added with fillers, additives, etc., and prepared using organic solvents or water. It is used for coating and forms a firmly attached continuous film on the surface of the coated object to protect or decorate the coated object.

[0003] Electromagnetic wave shielding coating is a kind of functional coating that is mixed with conductive particles in chemical solvents and can be sprayed on non-metallic materials such as ABS and other engineering plastics, fiberglass, wood, cement walls, etc. to shield electromagnetic waves. It has the advantages of room temperature curing and strong adhesion. It is the simplest treatment method for electromagnetic shielding of non-metallic shells of mobile phones, monitors, printers and various instruments.

[0004] Commonly used electromagnetic shielding coatings are mainly prepared by a composite method. They are composed of resins, diluents, additives and conductive fillers, etc., and are mainly conductive coatings. The conductive fillers added to the conductive coatings are generally metal powders such as gold, silver, copper, nickel and non-metallic powders such as carbon black and graphite. However, in the harsh environment of high temperature, high humidity, high salt fog and high radiation, the requirements for the anti-corrosion performance of absorbing coatings are getting higher and higher. Traditional absorbing coatings generally focus on improving the absorbing performance and ignore the anti-corrosion performance. Therefore, the present invention proposes an electromagnetic shielding absorbing coating with good corrosion resistance and a preparation method to solve the problems existing in the prior art. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to propose an electromagnetic shielding and absorbing coating with good corrosion resistance and a preparation method. The electromagnetic shielding and absorbing coating with good corrosion resistance and the preparation method have the advantage of high corrosion resistance and can solve the problems existing in the prior art.

[0006] To achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: an electromagnetic shielding and absorbing coating with good corrosion resistance and a preparation method, comprising the following raw materials in percentage by weight: 15-20 parts of polyurethane modified epoxy resin, 10-15 parts of polyethersulfone resin, 15-20 parts of silver-coated copper powder, 10-15 parts of graphene, 10-15 parts of zinc powder, 15-20 parts of polypyrrole, 2-3 parts of anticorrosive agent, 1-2.5 parts of coupling agent, 2-3 parts of antioxidant, 2-3 parts of anti-settling agent and 0.5-1 part of dispersant.

[0007] A further improvement is that the following raw materials are included in percentage by weight: It includes 15 parts of polyurethane modified epoxy resin, 15 parts of polyethersulfone resin, 20 parts of silver-coated copper powder, 10 parts of graphene, 10 parts of zinc powder, 20 parts of polypyrrole, 3 parts of anticorrosive agent, 2.5 parts of coupling agent, 2 parts of antioxidant, 2 parts of anti-settling agent and 0.5 parts of dispersant.

[0008] A further improvement is that the following raw materials are included in percentage by weight: The invention comprises 20 parts of polyurethane modified epoxy resin, 10 parts of polyethersulfone resin, 15 parts of silver-coated copper powder, 15 parts of graphene, 15 parts of zinc powder, 15 parts of polypyrrole, 2 parts of anticorrosive agent, 1 part of coupling agent, 3 parts of antioxidant, 3 parts of anti-settling agent and 1 part of dispersant.

[0009] A further improvement is that the anti-settling agent is one or more of organic bentonite, fumed silica and hydrogenated castor oil.

[0010] A further improvement is that the coupling agent is a silane coupling agent or an organic chromium coupling agent.

[0011] A further improvement is that the dispersant is a non-ionic dispersant or a polymer dispersant.

[0012] A further improvement is that the antioxidant is a benzoazole antioxidant.

[0013] A further improvement is that the anticorrosion agent is a phosphate anticorrosion agent.

[0014] A method for preparing an electromagnetic shielding and absorbing coating with good corrosion resistance, characterized in that it comprises the following steps: Step 1: Preparation of raw materials Prepare polyurethane modified epoxy resin, polyethersulfone resin, silver-coated copper powder, graphene, zinc powder, polypyrrole, anticorrosive agent, coupling agent, antioxidant, anti-settling agent and dispersant, and weigh them; Step 2: Pretreatment of raw materials Silver-coated copper powder, graphene, zinc powder and polypyrrole are put into a ball mill together for ball milling to obtain mixed filler powder, and then the mixed conductive filler is added into an ultrasonic disperser for ultrasonic dispersion to obtain conductive filler powder; Step 3: Mixing the paint Add the conductive filler powder obtained in step 2 into the mixer, and add the remaining raw materials in sequence, start mixing, and after the mixing is completed, obtain a mixed coating; Step 4: Preparation of coating The mixed coating obtained in step three is placed in a storage container and allowed to stand for 30-90 minutes for aging. After aging, an electromagnetic shielding and absorbing coating is obtained.

[0015] The beneficial effects of the present invention are as follows: the corrosion-resistant electromagnetic shielding and absorbing coating and preparation method provided by the present invention first use a mixture of polyurethane modified epoxy resin and polyethersulfone resin as a synthetic resin matrix, which can enhance the high temperature resistance and chemical corrosion resistance of the coating, and then add graphene and zinc powder for coordination, while ensuring conductivity, enhancing corrosion resistance, and finally anti-corrosion agents and antioxidants are used as auxiliary agents, thereby improving the stability and service life of the electromagnetic shielding and absorbing coating as a whole. In addition, in terms of conductivity, silver-coated copper powder and polypyrrole are introduced for coordination, which has good conductivity. Therefore, the present invention ensures the performance of the electromagnetic shielding and absorbing coating while improving its corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the steps of the preparation method of the present invention.

[0017] Figure 2 It is a schematic diagram for comparing the acid resistance grades of the present invention. DETAILED DESCRIPTION

[0018] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0019] The raw materials used in the following examples were all obtained through conventional commercial routes.

[0020] Embodiment 1 according to Figure 1 As shown, this embodiment provides an electromagnetic shielding and absorbing coating with good corrosion resistance, including the following raw materials in percentage by weight: It includes 15 parts of polyurethane modified epoxy resin, 15 parts of polyethersulfone resin, 20 parts of silver-coated copper powder, 10 parts of graphene, 10 parts of zinc powder, 20 parts of polypyrrole, 3 parts of anti-corrosion agent, 2.5 parts of coupling agent, 2 parts of antioxidant, 2 parts of anti-settling agent and 0.5 parts of dispersant, wherein the anti-settling agent is organic bentonite, the coupling agent is a silane coupling agent, the dispersant is BYK161 polymer dispersant, the antioxidant is a benzazole antioxidant, and the anti-corrosion agent is a phosphate anti-corrosion agent.

[0021] A method for preparing an electromagnetic shielding and absorbing coating with good corrosion resistance comprises the following steps: Step 1: Preparation of raw materials According to the raw material composition formula involved in this embodiment, polyurethane-modified epoxy resin, polyethersulfone resin, silver-coated copper powder, graphene, zinc powder, polypyrrole, anticorrosive agent, coupling agent, antioxidant, anti-settling agent and dispersant are prepared, and weighed and set aside after weighing; Step 2: Pretreatment of raw materials Silver-coated copper powder, graphene, zinc powder and polypyrrole are put into a ball mill for ball milling. The purpose of ball milling together is to fully crush and mix these materials to obtain uniform dispersion and good compatibility. If each material is ball milled separately and then mixed, it may cause unevenness at the interface between the materials, thereby affecting the final coating performance. Specifically, the ball milling time is 8h, the rotation speed is 600r / min, and the ball-to-material ratio is 7:1. Mixed filler powder is obtained after ball milling. In order to further refine the particle size of the mixed filler powder, the mixed conductive filler is added to an ultrasonic disperser for ultrasonic dispersion. Specifically, the ultrasonic frequency is 20kHz, the power is 1800w, and the dispersion time is 45min. Conductive filler powder is obtained after dispersion. Therefore, this embodiment adopts the method of ball milling and ultrasonic dispersion to pretreat silver-coated copper powder, graphene, zinc powder and polypyrrole to reduce the particle size and improve its dispersibility in the coating. Step 3: Mixing the paint Add the conductive filler powder obtained in step 2 into the mixer, and add the remaining raw materials in sequence. Specifically, first add the polyurethane modified epoxy resin and the polyethersulfone resin, start mixing, the mixer speed is 200r / min, after mixing for 10min, add the anticorrosive agent, coupling agent, antioxidant, anti-settling agent and dispersant, mix again, at this time increase the mixer speed, the speed is 400r / min, after mixing is completed, the mixed coating is obtained; Step 4: Preparation of coating The mixed coating obtained in step three is placed in a storage container and allowed to stand for 90 minutes for aging. After aging, an electromagnetic shielding and absorbing coating is obtained. The electromagnetic shielding and absorbing coating can be applied to subsequent coating operations, coated on a substrate, and then dried or cured.

[0022] Embodiment 2 according to Figure 1 As shown, this embodiment provides an electromagnetic shielding and absorbing coating with good corrosion resistance, including the following raw materials in percentage by weight: It includes 20 parts of polyurethane modified epoxy resin, 10 parts of polyethersulfone resin, 15 parts of silver-coated copper powder, 15 parts of graphene, 15 parts of zinc powder, 15 parts of polypyrrole, 2 parts of anti-corrosion agent, 1 part of coupling agent, 3 parts of antioxidant, 3 parts of anti-settling agent and 1 part of dispersant, wherein the anti-settling agent is hydrogenated castor oil, the coupling agent is an organic chromium coupling agent, the dispersant is a polyethylene glycol non-ionic dispersant, the antioxidant is a benzazole antioxidant, and the anti-corrosion agent is a phosphate anti-corrosion agent.

[0023] A method for preparing an electromagnetic shielding and absorbing coating with good corrosion resistance comprises the following steps: Step 1: Preparation of raw materials According to the raw material composition formula involved in this embodiment, polyurethane-modified epoxy resin, polyethersulfone resin, silver-coated copper powder, graphene, zinc powder, polypyrrole, anticorrosive agent, coupling agent, antioxidant, anti-settling agent and dispersant are prepared, and weighed and set aside after weighing; Step 2: Pretreatment of raw materials Silver-coated copper powder, graphene, zinc powder and polypyrrole are put into a ball mill for ball milling. The purpose of ball milling together is to fully crush and mix these materials to obtain uniform dispersion and good compatibility. If each material is ball milled separately and then mixed, it may cause unevenness at the interface between the materials, thereby affecting the final coating performance. Specifically, the ball milling time is 10h, the rotation speed is 600r / min, and the ball-to-material ratio is 7:1. Mixed filler powder is obtained after ball milling. In order to further refine the particle size of the mixed filler powder, the mixed conductive filler is added to an ultrasonic disperser for ultrasonic dispersion. Specifically, the ultrasonic frequency is 20kHz, the power is 1800w, and the dispersion time is 55min. Conductive filler powder is obtained after dispersion. Therefore, this embodiment adopts the method of ball milling and ultrasonic dispersion to pretreat silver-coated copper powder, graphene, zinc powder and polypyrrole to reduce the particle size and improve its dispersibility in the coating. Step 3: Mixing the paint The conductive filler powder obtained in step 2 is added into a mixer, and the remaining raw materials are added in sequence. Specifically, the coupling agent is first dissolved in ethanol to obtain a coupling agent solution, and then the solution is added into the mixer and mixing is started. The conductive filler powder is surface modified by the coupling agent to enhance the bonding force between the filler and the resin. Specifically, the mixer speed is 100r / min. After mixing for 1h, polyurethane-modified epoxy resin and polyethersulfone resin are added. The mixer speed is increased to 250r / min and mixed for 10min. Then, an anticorrosive agent, an antioxidant, an anti-settling agent and a dispersant are added and mixed again. At this time, the mixer speed is increased to 450r / min. After mixing, a mixed coating is obtained. Step 4: Preparation of coating The mixed coating obtained in step three is placed in a storage container and allowed to stand for 40 minutes for aging. After aging, an electromagnetic shielding and absorbing coating is obtained. The electromagnetic shielding and absorbing coating can be applied to subsequent coating operations, coated on a substrate, and then dried or cured.

[0024] Embodiment 3 according to Figure 1-Figure 2 As shown, this embodiment provides an electromagnetic shielding and absorbing coating with good corrosion resistance, including the following raw materials in percentage by weight: 18 parts of polyurethane modified epoxy resin, 12 parts of polyethersulfone resin, 17 parts of silver-coated copper powder, 13 parts of graphene, 12 parts of zinc powder, 18 parts of polypyrrole, 2.5 parts of anti-corrosion agent, 2 parts of coupling agent, 2.5 parts of antioxidant, 2.3 parts of anti-settling agent and 0.7 parts of dispersant, wherein the anti-settling agent is a mixture of organic bentonite and fumed silica in a ratio of 1.5:1, the coupling agent is a silane coupling agent, the dispersant is a BYK161 polymer dispersant, the antioxidant is a benzazole antioxidant, and the anti-corrosion agent is a phosphate anti-corrosion agent.

[0025] A method for preparing an electromagnetic shielding and absorbing coating with good corrosion resistance comprises the following steps: Step 1: Preparation of raw materials According to the raw material composition formula involved in this embodiment, polyurethane-modified epoxy resin, polyethersulfone resin, silver-coated copper powder, graphene, zinc powder, polypyrrole, anticorrosive agent, coupling agent, antioxidant, anti-settling agent and dispersant are prepared, and weighed and set aside after weighing; Step 2: Pretreatment of raw materials Silver-coated copper powder, graphene, zinc powder, and polypyrrole are put into a ball mill for ball milling. The purpose of ball milling together is to fully crush and mix these materials to obtain uniform dispersion and good compatibility. If each material is ball milled separately and then mixed, it may cause unevenness at the interface between the materials, thereby affecting the final coating performance. Specifically, the ball milling time is 12h, the speed is 500r / min, and the ball-to-material ratio is 7:1. After ball milling, a mixed filler powder is obtained. In order to further refine the particle size of the mixed filler powder, the mixed conductive filler is added to an ultrasonic disperser for ultrasonic dispersion. Specifically, the ultrasonic frequency is 20kHz, the power is 1800w, and the dispersion time is 55min. After dispersion, a conductive filler powder is obtained. Therefore, this embodiment adopts ball milling and ultrasonic dispersion to pre-treat silver-coated copper powder, graphene, zinc powder, and polypyrrole to reduce the particle size and improve its dispersion in the coating; Step 3: Mixing the paint Add the conductive filler powder obtained in step 2 into the mixer, and add the remaining raw materials in sequence. Specifically, first add the polyurethane modified epoxy resin and the polyethersulfone resin, start mixing, the mixer speed is 200r / min, after mixing for 5min, add the anticorrosive agent, coupling agent, antioxidant, anti-settling agent and dispersant, mix again, at this time increase the mixer speed, the speed is 500r / min, after mixing is completed, the mixed coating is obtained; Step 4: Preparation of coating The mixed coating obtained in step three is placed in a storage container and allowed to stand for 60 minutes for aging. After aging, an electromagnetic shielding and absorbing coating is obtained. The electromagnetic shielding and absorbing coating can be applied to subsequent coating operations, coated on a substrate, and then dried or cured.

[0026] In this embodiment, polyurethane modified epoxy resin has excellent bonding properties and mechanical properties, while polyethersulfone resin has excellent heat resistance and chemical resistance. Silver-coated copper powder is a commonly used electromagnetic shielding and absorbing coating component, which combines the advantages of silver and copper, has good conductivity and certain cost advantages, and then works synergistically with polypyrrole to improve the conductivity and shielding effectiveness of the coating. Then, graphene, as a new type of two-dimensional material, has excellent conductivity and corrosion resistance, and zinc powder is widely used in electromagnetic shielding and absorbing coatings due to its good electromagnetic loss characteristics.

[0027] In combination with Example 1, Example 2 and Example 3, a control group is set up, which is an existing purchased electromagnetic shielding and absorbing coating, and an acid resistance test is performed. The detection method is: at a temperature of 80°C, the sample is immersed in a sulfuric acid solution with a mass concentration of 30% for 15 days, and the damage of the coating after immersion is observed. At the same time, the damage level is divided into one to four levels, among which the first-level marking coating has the best acid resistance. Figure 2 As shown, the electromagnetic shielding and absorbing coatings prepared in Example 1, Example 2 and Example 3 have a first-level acid resistance, which shows that Examples 1, 2 and 3 of the present invention have excellent corrosion resistance. Next, the samples are reset, and the electromagnetic shielding and absorbing coatings prepared in Example 1, Example 2 and Example 3 are coated on the sample plate, and then a neutral salt spray test is carried out. After 72 hours of salt spray resistance test, no blistering, shedding and corrosion occur.

[0028] The samples were reset, and the electromagnetic shielding and absorbing coatings prepared in Example 1, Example 2 and Example 3 were coated on the sample plate. The shielding effectiveness and dielectric properties (volume resistivity) of the coatings against electromagnetic waves were tested in the test frequency range of 8 to 40 GHz using a coaxial fixture and a network analyzer, as shown in the following table: Average electromagnetic shielding effectiveness Volume resistivity Embodiment 1 21.2 / dB 0.011 / Ω·cm Embodiment 2 20.5 / dB 0.010 / Ω·cm Embodiment 3 22.3 / dB 0.009 / Ω·cm Control group 15.2 / dB 0.025 / Ω·cm Therefore, the corrosion-resistant electromagnetic shielding and absorbing coating and preparation method provided by the present invention first use a mixture of polyurethane modified epoxy resin and polyethersulfone resin as a synthetic resin matrix, which can enhance the high temperature resistance and chemical corrosion resistance of the coating, and then add graphene and zinc powder for coordination, while ensuring conductivity and enhancing corrosion resistance, and finally anti-corrosion agents and antioxidants are used as auxiliary agents, thereby improving the stability and service life of the electromagnetic shielding and absorbing coating as a whole. In addition, in terms of conductivity, silver-coated copper powder and polypyrrole are introduced for coordination, which has good conductivity. Therefore, the present invention ensures the performance of the electromagnetic shielding and absorbing coating while improving its corrosion resistance.

[0029] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the framework and scope of application of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An electromagnetic shielding and absorbing coating with good corrosion resistance, characterized in that: The following raw materials are included in percentage by weight: 15-20 parts of polyurethane modified epoxy resin, 10-15 parts of polyethersulfone resin, 15-20 parts of silver-coated copper powder, 10-15 parts of graphene, 10-15 parts of zinc powder, 15-20 parts of polypyrrole, 2-3 parts of anticorrosive agent, 1-2.5 parts of coupling agent, 2-3 parts of antioxidant, 2-3 parts of anti-settling agent and 0.5-1 part of dispersant.

2. The electromagnetic shielding and absorbing coating with good corrosion resistance according to claim 1, characterized in that: The following raw materials are included in percentage by weight: It includes 15 parts of polyurethane modified epoxy resin, 15 parts of polyethersulfone resin, 20 parts of silver-coated copper powder, 10 parts of graphene, 10 parts of zinc powder, 20 parts of polypyrrole, 3 parts of anticorrosive agent, 2.5 parts of coupling agent, 2 parts of antioxidant, 2 parts of anti-settling agent and 0.5 parts of dispersant.

3. The electromagnetic shielding and absorbing coating with good corrosion resistance according to claim 1, characterized in that: The following raw materials are included in percentage by weight: The invention comprises 20 parts of polyurethane modified epoxy resin, 10 parts of polyethersulfone resin, 15 parts of silver-coated copper powder, 15 parts of graphene, 15 parts of zinc powder, 15 parts of polypyrrole, 2 parts of anticorrosive agent, 1 part of coupling agent, 3 parts of antioxidant, 3 parts of anti-settling agent and 1 part of dispersant.

4. The electromagnetic shielding and absorbing coating with good corrosion resistance according to claim 1, characterized in that: The anti-settling agent is one or more of organic bentonite, fumed silica and hydrogenated castor oil.

5. The electromagnetic shielding and absorbing coating with good corrosion resistance according to claim 1, characterized in that: The coupling agent is a silane coupling agent or an organic chromium coupling agent.

6. The electromagnetic shielding and absorbing coating with good corrosion resistance according to claim 1, characterized in that: The dispersant is a non-ionic dispersant or a polymer dispersant.

7. The electromagnetic shielding and absorbing coating with good corrosion resistance according to claim 1, characterized in that: The antioxidant is a benzoazole antioxidant.

8. The electromagnetic shielding and absorbing coating with good corrosion resistance according to claim 1, characterized in that: The anticorrosive agent is a phosphate anticorrosive agent.

9. A method for preparing an electromagnetic shielding and absorbing coating with good corrosion resistance as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Preparation of raw materials Prepare polyurethane modified epoxy resin, polyethersulfone resin, silver-coated copper powder, graphene, zinc powder, polypyrrole, anticorrosive agent, coupling agent, antioxidant, anti-settling agent and dispersant, and weigh them; Step 2: Pretreatment of raw materials Silver-coated copper powder, graphene, zinc powder and polypyrrole are put into a ball mill together for ball milling to obtain mixed filler powder, and then the mixed conductive filler is added into an ultrasonic disperser for ultrasonic dispersion to obtain conductive filler powder; Step 3: Mixing the paint Add the conductive filler powder obtained in step 2 into the mixer, and add the remaining raw materials in sequence, start mixing, and after the mixing is completed, obtain a mixed coating; Step 4: Preparation of coating The mixed coating obtained in step three is placed in a storage container and allowed to stand for 30-90 minutes for aging. After aging, an electromagnetic shielding and absorbing coating is obtained.

Images