阅读说明：本技术 一种羰基铁粉颗粒表面包覆高疏水层的方法 (Method for coating high-hydrophobic layer on surfaces of carbonyl iron powder particles ) 是由 彭峪清 秦蓬波 吴松华 于 2020-11-17 设计创作，主要内容包括：本发明公开一种羰基铁粉颗粒的表面包覆方法,包括首先对羰基铁粉除水,然后先后以氨基硅烷偶联剂以及硅氮烷对羰基铁粉进行反应,使得羰基铁粉表面产生出一层致密的甲基硅烷结构,利用其高疏水性实现对羰基铁粉的防腐保护,并且不影响其电磁吸收性能。氨基硅烷采用3-氨丙基甲基二乙氧基硅烷和3-氨丙基三乙氧基硅烷的一种或二者的混合物,硅氮烷采用化学纯的1,1,1-三甲基-N-(三甲基甲硅烷基)硅烷胺。本发明工艺流程简单,可以实现对羰基铁粉颗粒表面的完整包覆,并且具备公斤级别的处理能力,可以有效提升对应的吸波材料的耐湿热、耐盐雾腐蚀性能,提升其使用寿命。(The invention discloses a surface coating method of carbonyl iron powder particles, which comprises the steps of removing water from carbonyl iron powder, and reacting the carbonyl iron powder with an aminosilane coupling agent and silazane in sequence to generate a layer of compact methylsilane structure on the surface of the carbonyl iron powder, so that the carbonyl iron powder is protected from corrosion by utilizing the high hydrophobicity of the methylsilane structure, and the electromagnetic absorption performance of the carbonyl iron powder is not influenced. The aminosilane is one or a mixture of 3-aminopropylmethyldiethoxysilane and 3-aminopropyltriethoxysilane, and the silazane is chemically pure 1,1, 1-trimethyl-N- (trimethylsilyl) silanamine. The method has simple process flow, can realize complete coating of the surfaces of carbonyl iron powder particles, has kilogram-grade processing capacity, can effectively improve the humidity resistance, heat resistance and salt spray corrosion resistance of the corresponding wave-absorbing material, and prolongs the service life of the wave-absorbing material.)

1. A method for coating a high hydrophobic layer on the surface of carbonyl iron powder particles comprises the following steps:

adding a certain amount of carbonyl iron powder subjected to vacuum dehydration into enough absolute ethyl alcohol, stirring until the carbonyl iron powder is completely dispersed, then adding an aminosilane coupling agent, fully reacting with the carbonyl iron powder, then adding hexamethyldisilazane, reacting for a certain time at a certain temperature while stirring, and filtering the carbonyl iron powder coated on the surface after the reaction is finished, wherein the addition amount of the silane coupling agent is 1-2 ml and the addition amount of the hexamethyldisilazane is 3-5 ml per 100 g of carbonyl iron powder.

2. The method according to claim 1, wherein the silane coupling agent is added in an amount of 1ml and the hexamethyldisilazane is added in an amount of 3 to 4ml per 100 g of carbonyl iron powder.

3. The method according to claim 1, further comprising the step of washing the filtered surface-coated carbonyl iron powder with anhydrous ethanol and drying.

4. The method according to claim 1, wherein the carbonyl iron powder contains not less than 98% by weight of iron, has a particle diameter of 1 to 10 μm, and has a true density of 7.8 to 8.2g/cm³。

5. The process according to claim 1, wherein the aminosilane coupling agent is 3-aminopropylmethyldiethoxysilane and/or 3-aminopropyltriethoxysilane.

6. The method of claim 5, wherein the aminosilane coupling agent is a mixture of 3-aminopropylmethyldiethoxysilane and 3-aminopropyltriethoxysilane in a 1:1 volume ratio.

7. The process of claim 1 wherein the hexamethyldisilazane is 1,1, 1-trimethyl-N- (trimethylsilyl) silanamine.

8. The method according to claim 1, wherein the certain temperature is 10 to 25 degrees celsius and the certain time is 6 to 24 hours.

Technical Field

The invention belongs to the technical field of chemical materials and production thereof, and particularly relates to a method for coating a high-hydrophobic layer on the surface of carbonyl iron powder particles.

Background

In the modern military countermeasure system, the detection/counter-detection means is always a hot direction for research and development; the radar wave-absorbing material prepared by adding various electromagnetic wave absorbers serving as fillers into a base body such as rubber, resin and the like can absorb and attenuate incident electromagnetic waves and weaken the intensity of reflected echoes, thereby achieving the purpose of reducing the scattering cross section of a target radar. Carbonyl iron powder is a widely used electromagnetic wave absorbent, has the characteristics of high magnetic conductivity, good real part and imaginary part frequency dispersion characteristics of the magnetic conductivity, and has strong absorption efficiency on radar waves under the condition of low matching thickness. Researches show that carbonyl iron powder serving as filler is prepared into wave-absorbing rubber, wave-absorbing coating, wave-absorbing putty and the like, has good electromagnetic stealth effect and is difficult to replace by other electromagnetic wave absorbers.

In practical application, the various wave-absorbing materials are often in contact with a complex environment state, and the corrosion resistance of the materials is an important consideration. Ships or aircrafts often need to be in service in tropical marine climate environments with high temperature, high humidity and high salinity, and at the moment, carbonyl iron powder serving as a filler can be quickly corroded, so that the wave-absorbing material loses effectiveness, and the mechanical property and the electromagnetic absorption capacity of the wave-absorbing material are influenced. Therefore, it is urgently needed to develop a surface coating process for carbonyl iron powder particles to improve the humidity and heat resistance and salt spray corrosion resistance of the wave-absorbing material.

Disclosure of Invention

In view of the above situation in the prior art, the present invention aims to provide a method for coating a high hydrophobic layer on the surface of carbonyl iron powder particles, so as to solve the problem that carbonyl iron powder is easy to rust and improve the environmental resistance of the wave-absorbing material.

The above object of the present invention is achieved by the following technical solutions:

a method for coating a high hydrophobic layer on the surface of carbonyl iron powder particles comprises the following steps:

adding a certain amount of carbonyl iron powder subjected to vacuum dehydration into enough absolute ethyl alcohol, stirring until the carbonyl iron powder is completely dispersed, then adding an aminosilane coupling agent, fully reacting with carbonyl iron powder, then adding hexamethyldisilazane, stirring, reacting for a certain time at the temperature of 10-25 ℃, and filtering out carbonyl iron powder coated on the surface after the reaction is finished, wherein the addition amount of the silane coupling agent is 1-2 ml and the addition amount of the hexamethyldisilazane is 3-5 ml per 100 g of carbonyl iron powder. Preferably, the adding amount of the silane coupling agent is 1ml and the adding amount of the hexamethyldisilazane is 3-4 ml per 100 g of carbonyl iron powder.

The method also comprises the step of washing the filtered carbonyl iron powder with absolute ethyl alcohol, and drying, wherein the drying is carried out in an oven at 70 ℃ for 6 hours.

The weight percentage content of the iron element of the carbonyl iron powder is more than or equal to 98 percent, the particle diameter is 1-10 mu m, and the true density is 7.8-8.2 g/cm³。

The amino silane coupling agent is 3-aminopropyl methyl diethoxy silane, chemically pure and/or 3-aminopropyl triethoxy silane, and has no special requirement on the mixing ratio of the 3-aminopropyl methyl diethoxy silane and the 3-aminopropyl triethoxy silane when the amino silane coupling agent is a mixture of the two.

The hexamethyldisilazane is 1,1, 1-trimethyl-N- (trimethylsilyl) silanamine, chemically pure.

According to the invention, an aminosilane coupling agent reacts with the surface of carbonyl iron powder to generate silicon hydroxyl on the surface of the carbonyl iron powder, and then the silicon hydroxyl reacts with hexamethyldisilazane to grow a hydrophobic methylsilyl structure, so that the complete and compact coating on the surface of the carbonyl iron powder is realized. After the coated carbonyl iron powder and the polysulfide rubber matrix are mixed to prepare the wave-absorbing material, the coating layer on the surface can isolate the contact of the carbonyl iron powder with moisture and salt mist, thereby ensuring the corrosion resistance of the carbonyl iron powder; in addition, the dispersion effect of carbonyl iron powder particles can be improved, and the wave-absorbing performance of the material is optimized.

Detailed Description

In order to clearly understand the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following embodiments.

Example 1:

firstly weighing 1Kg of carbonyl iron powder, drying for 4 hours in a vacuum oven at 90 ℃, removing the excessive bound water on the surface of the carbonyl iron powder, and hydroxylating the surface of the carbonyl iron powder. Under vacuum environment, after cooling to room temperature, adding into 10Kg absolute ethyl alcohol, and placing in a reaction kettle, and continuously stirring for 1 day at normal temperature to completely disperse. Then 10ml of 3-aminopropylmethyldiethoxysilane is added into the suspension, stirring is continued for 3h, then 30ml of hexamethyldisilazane is added, stirring is carried out for 1 day, and the reaction kettle is circularly cooled by tap water while the whole reaction is carried out, and the temperature is kept to be not more than 25 ℃. And after the reaction is finished, carrying out suction filtration to obtain coated carbonyl iron powder, washing twice with absolute ethyl alcohol, washing off redundant reactants, drying in an oven at 70 ℃ for 6 hours, and fully volatilizing redundant ethyl alcohol and product ammonia gas to finish the treatment of the carbonyl iron powder. The product should be stored in a cool, ventilated place.

Example 2:

firstly weighing 1Kg of carbonyl iron powder, drying for 4 hours in a vacuum oven at 90 ℃, removing the excessive bound water on the surface of the carbonyl iron powder, and hydroxylating the surface of the carbonyl iron powder. Under vacuum environment, after cooling to room temperature, adding into 10Kg absolute ethyl alcohol, and placing in a reaction kettle, and continuously stirring for 1 day at normal temperature to completely disperse. Subsequently, 10ml of 3-aminopropyltriethoxysilane was added to the suspension, and after stirring was continued for 5 hours, 45ml of hexamethyldisilazane was added and the reaction was allowed to react for 2 days with stirring, and the reaction vessel was circulated with tap water while the entire reaction was carried out, keeping the temperature at 25 ℃ or lower. And after the reaction is finished, carrying out suction filtration to obtain coated carbonyl iron powder, washing twice with absolute ethyl alcohol, washing off redundant reactants, drying in an oven at 70 ℃ for 6 hours, and fully volatilizing redundant ethyl alcohol and product ammonia gas to finish the treatment of the carbonyl iron powder. The product should be stored in a cool, ventilated place.

Example 3:

firstly weighing 1Kg of carbonyl iron powder, drying for 4 hours in a vacuum oven at 90 ℃, removing the excessive bound water on the surface of the carbonyl iron powder, and hydroxylating the surface of the carbonyl iron powder. Under vacuum environment, after cooling to room temperature, adding into 10Kg absolute ethyl alcohol, and placing in a reaction kettle, and continuously stirring for 1 day at normal temperature to completely disperse. Then, a 1:1 (volume ratio) mixture of 3-aminopropyltriethoxysilane and 3-aminopropylmethyldiethoxysilane was added to the suspension, 10ml was added, stirring was continued for 3 hours until the reaction was completed, 40ml of hexamethyldisilazane was added and the mixture was reacted for 1 day with stirring, and the whole reaction kettle was circulated with tap water while keeping the temperature at 25 ℃ or below. And after the reaction is finished, carrying out suction filtration to obtain coated carbonyl iron powder, washing twice with absolute ethyl alcohol, washing off redundant reactants, drying in an oven at 70 ℃ for 6 hours, and fully volatilizing redundant ethyl alcohol and product ammonia gas to finish the treatment of the carbonyl iron powder. The product should be stored in a cool, ventilated place.

And (3) uniformly mixing the carbonyl iron powder subjected to surface treatment and the untreated carbonyl iron powder with the polysulfide crude rubber, adding a certain proportion of manganese dioxide vulcanizing agent, and vulcanizing in a proper mold to obtain the corresponding polysulfide rubber with the wave absorbing function. Then the corrosion resistance of the alloy is respectively tested in a damp-heat tester under the conditions of 25 ℃ and 95% RH humidity. The results show that the surface coating treatment of the carbonyl iron powder particles is complete and compact, the corrosion process of the carbonyl iron powder can be effectively weakened, and the corrosion resistance of the wave-absorbing material is improved.

1. The silane coupling agent adopted by the invention is 3-aminopropyl methyl diethoxysilane or 3-aminopropyl triethoxy silane, which has high active amino group and is very easy to adsorb with hydroxyl on the surface of carbonyl iron powder to react, so that active silicon hydroxyl is introduced on the surface of the iron powder, and the full reaction with hexamethyldisilazane is facilitated.

2. According to the invention, after hexamethyldisilazane is reacted with silicon hydroxyl, a layer of highly hydrophobic methylsilane structure can be formed to protect the outer side of carbonyl iron powder, so that the carbonyl iron powder can be effectively isolated from being contacted with moisture or salt mist, and the corrosion resistance of the carbonyl iron powder is ensured. Compared with the common processing mode of Tetraethoxysilane (TEOS) + 3-aminopropyl triethoxysilane (APTES), the silane protective layer generated in the technology is more compact and complete, and has relatively more excellent anticorrosion performance.

3. The whole process of the treatment process is in an anhydrous state, so that the reactant aminosilane coupling agent and hexamethyldisilazane can be effectively prevented from being hydrolyzed to influence the integrity of a carbonyl iron powder coating structure.

4. The silane protective layer coated by the carbonyl iron powder is a wave-transparent material, and has no adverse effect on the electromagnetic absorption capacity of the carbonyl iron powder. Meanwhile, the effective dispersion of carbonyl iron powder particles is realized in the treatment process, so that the technological performance of the carbonyl iron powder particles as rubber filler is effectively improved.

5. The invention realizes the coating treatment process of kilogram-grade carbonyl iron powder and has theoretical possibility in actual industrial production.