阅读说明：本技术 一种耐水白化水性吸波涂料及其制备方法 (Water-whitening-resistant water-based wave-absorbing coating and preparation method thereof ) 是由 罗振涛 王浩继 丁铁伢 王建国 程文 甘丹 于 2020-08-04 设计创作，主要内容包括：本发明公开了一种耐水白化水性吸波涂料及其制备方法,包括水、丙烯酸酯类单体混合物、水溶性引发剂、乳化剂、pH调节剂、电磁波吸收剂、水溶性消泡剂、水溶性流平剂、水溶性防沉剂、水溶性分散剂,与现有技术相比,本发明通过控制软、硬单体及功能单体的比例,并采用半连续种子乳液聚合方式制备了水性吸波涂料。该水性吸波涂料中乳胶粒子具有一定的核壳结构,粒子间作用稳定,不易受到体系pH值、温度等因素的影响。制得的乳胶膜耐水性及耐水白化性能优异。将乳胶膜在25℃水中浸泡24h后,其透光率仍高于70％；吸波涂层的吸波强度超过-10dB的有效带宽大于7.5GHz,吸收峰值达-30dB。(The invention discloses a water-whitening resistant water-based wave-absorbing coating and a preparation method thereof, and the water-whitening resistant water-based wave-absorbing coating comprises water, an acrylate monomer mixture, a water-soluble initiator, an emulsifier, a pH regulator, an electromagnetic wave absorbent, a water-soluble defoaming agent, a water-soluble leveling agent, a water-soluble anti-settling agent and a water-soluble dispersing agent. The latex particles in the water-based wave-absorbing coating have a certain core-shell structure, the interaction between the particles is stable, and the influence of factors such as the pH value and the temperature of a system is not easy to influence. The prepared latex film has excellent water resistance and water whitening resistance. After the latex film is soaked in water at 25 ℃ for 24 hours, the light transmittance is still higher than 70%; the effective bandwidth of the wave-absorbing coating exceeding-10 dB is larger than 7.5GHz, and the absorption peak value reaches-30 dB.)

1. A water whitening resistant water-based wave-absorbing coating is characterized in that: comprises the following components in percentage by weight:

water: 10% -15%, acrylate monomer mixture: 25.0% -35.0%, water-soluble initiator: 3.0% -5.0%, emulsifier: 2.0% -4.0%, pH regulator: 0.1% -0.5%, electromagnetic wave absorber: 45.0% -55.0%, water-soluble defoaming agent: 0.1% -0.5%, water-soluble leveling agent: 0.5% -1.0%, water-soluble anti-settling agent: 0.5% -1.0%, water-soluble dispersant: 0.5 to 1.0 percent.

2. The water whitening resistant aqueous wave-absorbing coating of claim 1, characterized in that: the acrylic ester monomer mixture comprises a hard monomer, a soft elastomer and a functional monomer; the hard monomer is one or more of methyl methacrylate, styrene, acrylonitrile and methyl acrylate; the soft monomer is one or more of isooctyl acrylate, ethyl acrylate and butyl acrylate; the functional monomer is one or more of acrylic acid, hydroxyethyl acrylate, hydroxypropyl methacrylate and glycidyl methacrylate.

3. The water whitening resistant aqueous wave-absorbing coating of claim 1, characterized in that: the water-soluble initiator is one or more of ammonium persulfate, potassium persulfate and azo initiator VA 044; the emulsifier is one or more of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, Cyanote EF-800 emulsifier, CO-436 emulsifier, CO-897 emulsifier and CW-3008 emulsifier; the pH regulator is one of ammonia water and sodium hydroxide aqueous solution; the electromagnetic wave absorbent is one or more of barium titanate, silicon carbide, carbon black, polyaniline, single-walled carbon nanotube, graphene and ferrite; the water-soluble defoaming agent is one or more of Gaoka CK-C5001, CK-M026, Nanhui CI-1104, Tiande DJ-1327, Delong DF-3224, Pasf A38 and national DU-077; the water-soluble leveling agent is one or more of BYK-381, BYK-346, BYK-333, Silok-355, Qingtian DH-4310 and Rohm Haas 2020 NPR; the water-soluble anti-settling agent is one or more of Kogyang KYC-426, Qingtian DH-6900, Jinyuan 2654623 and Lisheng FC-7155W; the water-soluble dispersant is one or more of Silok-7155W, Qingtian DH-6000, Hensk H-791 and Lida chemical LD-64192.

4. A preparation method of a water-whitening-resistant water-based wave-absorbing coating is characterized by comprising the following steps: the method comprises the following steps:

1) according to the weight percentage of water: 10% -15%, acrylate monomer mixture: 25.0% -35.0%, water-soluble initiator: 3.0% -5.0%, emulsifier: 2.0% -4.0%, pH regulator: 0.1% -0.5%, electromagnetic wave absorber: 45.0% -55.0%, water-soluble defoaming agent: 0.1% -0.5%, water-soluble leveling agent: 0.5% -1.0%, water-soluble anti-settling agent: 0.5% -1.0%, water-soluble dispersant: weighing 0.5-1.0% of each component for later use, taking out 10% of the total amount of the acrylate monomer mixture into a flask, and adding all water;

2) adding all the emulsifier into the flask in the step 1);

3) preparing a water-soluble initiator into an initiator aqueous solution with the concentration of 1%, taking out 1/3, adding the initiator aqueous solution into the flask obtained in the step 1), heating the initiator aqueous solution in a water bath to 70 ℃, and initiating polymerization at a fixed stirring speed to generate a seed emulsion;

4) dropwise adding the rest acrylate monomer mixture and an initiator aqueous solution into the seed emulsion obtained in the step 3) at a constant speed, and continuously initiating polymerization at 80 ℃ until the polymerization is complete;

5) keeping the temperature of the polymerized emulsion in the step 4) for 1-2h, naturally cooling to room temperature, filtering and discharging, and adjusting the pH of the emulsion to be neutral by adopting a pH regulator to obtain the water whitening resistant polyacrylate emulsion;

6) adding the electromagnetic wave absorbent, the water-soluble defoaming agent, the water-soluble leveling agent, the water-soluble anti-settling agent and the water-soluble dispersing agent into the water-whitening resistant polyacrylate emulsion prepared in the step 5) to obtain the water-whitening resistant water-based wave-absorbing coating.

5. The preparation method of the water whitening resistant water-based wave-absorbing coating of claim 4, which is characterized by comprising the following steps: the average particle diameter of latex particles in the prepared water-whitening resistant polyacrylate emulsion is 90-100nm, and the pH value of the emulsion is 7-8.

6. The preparation method of the water whitening resistant water-based wave-absorbing coating of claim 4, which is characterized by comprising the following steps: after the latex film formed by coating the water-whitening resistant water-based wave-absorbing coating is soaked in water at 25 ℃ for 24 hours, the light transmittance of the latex film is still higher than 70%.

7. The preparation method of the water whitening resistant water-based wave-absorbing coating of claim 4, which is characterized by comprising the following steps: the effective bandwidth of the coating formed by the water-whitening resistant water-based wave-absorbing coating is less than-10 dB and exceeds 7.5GHz, and the absorption peak exceeds-30 dB.

8. The application of the water-whitening-resistant water-based wave-absorbing coating is characterized in that: the multifunctional invisible aircraft is used for any one of military invisible aircrafts, radars, household appliances, floor outer walls, mobile base stations and medical instruments.

Technical Field

The invention relates to the technical field of wave-absorbing coatings, in particular to a water-whitening-resistant water-based wave-absorbing coating and a preparation method thereof.

Background

With the rapid development of high and new technologies such as electronization and informatization, electronic products such as microwave ovens, mobile phones, wireless networks, medical equipment and the like are increasing in production and life, and are more and more widely applied to various fields of national economy and family life. People have to bear the harm of electromagnetic radiation to human bodies while enjoying huge convenience brought by electric power, wireless communication and household appliances, and the harm has an accumulative effect. In addition, electromagnetic radiation can cause significant electromagnetic interference to electronic devices and equipment. Therefore, the research on the wave-absorbing material is receiving much attention from all countries around the world. Moreover, the wave-absorbing material is also used in the military field, and the use of the wave-absorbing material improves the war survival capacity of stealth weapons.

The coating type wave-absorbing material is formed by mixing an absorbent and an adhesive and then coating the mixture on the surface of a target to form a wave-absorbing coating, is one of the earliest wave-absorbing materials, and has the characteristics of simple use, flexibility and adjustability, good wave-absorbing performance and the like. However, in the using process, a large amount of volatile organic solvent can cause secondary pollution to human bodies and the environment. The water-based environment-friendly radar wave-absorbing coating well solves the problems, and compared with a solvent-based wave-absorbing coating, the water-based wave-absorbing coating takes water as a dispersion medium, has the characteristics of no volatilization of organic gas, low odor and the like, and is a non-toxic environment-friendly product for military and civil use.

In the preparation process of the emulsion polymer, the emulsion polymer is water-sensitive due to the introduction of water-soluble initiators, surfactants and the like. When the latex film contacts with water, small water sacs with refractive index different from that of the polymer are generated among latex particles due to water absorption, so that light is scattered and whitened. The whitening phenomenon when meeting water can generate a lot of negative effects on the latex film, not only can affect the beauty of the wave absorbing coating, but also can generate great negative effects on the wave absorbing performance of the wave absorbing coating. However, none of the water-whitening resistance properties of the water-based resins currently on the market can achieve a good level. Therefore, before the water-based wave-absorbing coating is used for replacing the traditional solvent-based wave-absorbing coating, the improvement of the water whitening resistance of the wave-absorbing coating is an important difficult problem to be solved urgently.

Disclosure of Invention

The invention aims to provide a water-based wave-absorbing coating resistant to water whitening and a preparation method thereof, aiming at overcoming the defects of poor water whitening resistance, narrow frequency band, poor wave-absorbing performance and the like of the existing wave-absorbing coating.

The invention realizes the purpose through the following technical scheme:

the invention relates to a water-whitening-resistant water-based wave-absorbing coating which comprises the following components in percentage by weight:

water: 10% -15%, acrylate monomer mixture: 25.0% -35.0%, water-soluble initiator: 3.0% -5.0%, emulsifier: 2.0% -4.0%, pH regulator: 0.1% -0.5%, electromagnetic wave absorber: 45.0% -55.0%, water-soluble defoaming agent: 0.1% -0.5%, water-soluble leveling agent: 0.5% -1.0%, water-soluble anti-settling agent: 0.5% -1.0%, water-soluble dispersant: 0.5 to 1.0 percent.

The acrylic ester monomer mixture comprises a hard monomer, a soft elastomer and a functional monomer; the hard monomer is one or more of methyl methacrylate, styrene, acrylonitrile and methyl acrylate; the soft monomer is one or more of isooctyl acrylate, ethyl acrylate and butyl acrylate; the functional monomer is one or more of acrylic acid, hydroxyethyl acrylate, hydroxypropyl methacrylate and glycidyl methacrylate.

The water-soluble initiator is one or more of ammonium persulfate, potassium persulfate and azo initiator VA 044; the emulsifier is one or more of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, Cyanote EF-800 emulsifier, CO-436 emulsifier, CO-897 emulsifier and CW-3008 emulsifier; the pH regulator is one of ammonia water and sodium hydroxide aqueous solution; the electromagnetic wave absorbent is one or more of barium titanate, silicon carbide, carbon black, polyaniline, single-walled carbon nanotube, graphene and ferrite; the water-soluble defoaming agent is one or more of Gaoka CK-C5001, CK-M026, Nanhui CI-1104, Tiande DJ-1327, Delong DF-3224, Pasf A38 and national DU-077; the water-soluble leveling agent is one or more of BYK-381, BYK-346, BYK-333, Silok-355, Qingtian DH-4310 and Rohm Haas 2020 NPR; the water-soluble anti-settling agent is one or more of Kogyang KYC-426, Qingtian DH-6900, Jinyuan 2654623 and Lisheng FC-7155W; the water-soluble dispersant is one or more of Silok-7155W, Qingtian DH-6000, Hensk H-791 and Lida chemical LD-64192.

The invention relates to a preparation method of a water-whitening-resistant water-based wave-absorbing coating, which comprises the following steps:

1) according to the weight percentage of water: 10% -15%, acrylate monomer mixture: 25.0% -35.0%, water-soluble initiator: 3.0% -5.0%, emulsifier: 2.0% -4.0%, pH regulator: 0.1% -0.5%, electromagnetic wave absorber: 45.0% -55.0%, water-soluble defoaming agent: 0.1% -0.5%, water-soluble leveling agent: 0.5% -1.0%, water-soluble anti-settling agent: 0.5% -1.0%, water-soluble dispersant: weighing 0.5-1.0% of each component for later use, taking out 10% of the total amount of the acrylate monomer mixture into a flask, and adding all water;

2) adding all the emulsifier into the flask in the step 1);

3) preparing a water-soluble initiator into an initiator aqueous solution with the concentration of 1%, taking out 1/3, adding the initiator aqueous solution into the flask obtained in the step 1), heating the initiator aqueous solution in a water bath to 70 ℃, and initiating polymerization at a fixed stirring speed to generate a seed emulsion;

4) dropwise adding the rest acrylate monomer mixture and an initiator aqueous solution into the seed emulsion obtained in the step 3) at a constant speed, and continuously initiating polymerization at 80 ℃ until the polymerization is complete;

5) keeping the temperature of the polymerized emulsion in the step 4) for 1-2h, naturally cooling to room temperature, filtering and discharging, and adjusting the pH of the emulsion to be neutral by adopting a pH regulator to obtain the water whitening resistant polyacrylate emulsion;

6) adding the electromagnetic wave absorbent, the water-soluble defoaming agent, the water-soluble leveling agent, the water-soluble anti-settling agent and the water-soluble dispersing agent into the water-whitening resistant polyacrylate emulsion prepared in the step 5) to obtain the water-whitening resistant water-based wave-absorbing coating.

The average particle diameter of latex particles in the prepared water-whitening resistant polyacrylate emulsion is 90-100nm, and the pH value of the emulsion is 7-8. After the latex film formed by coating the water-whitening resistant water-based wave-absorbing coating is soaked in water at 25 ℃ for 24 hours, the light transmittance of the latex film is still higher than 70%. The effective bandwidth of the coating formed by the water-whitening resistant water-based wave-absorbing coating is less than-10 dB and exceeds 7.5GHz, and the absorption peak exceeds-30 dB.

The invention relates to an application of a water-whitening-resistant water-based wave-absorbing coating, which is used for any one of military stealth airplanes, radars, household appliances, floor outer walls, mobile base stations and medical instruments.

The invention has the beneficial effects that:

compared with the prior art, the invention prepares the water-based wave-absorbing coating by controlling the proportion of soft and hard monomers and functional monomers and adopting a semi-continuous seed emulsion polymerization mode. The latex particles in the water-based wave-absorbing coating have a certain core-shell structure, the interaction between the particles is stable, and the influence of factors such as the pH value and the temperature of a system is not easy to influence. The prepared latex film has excellent water resistance and water whitening resistance. After the latex film is soaked in water at 25 ℃ for 24 hours, the light transmittance is still higher than 70%; the effective bandwidth of the wave-absorbing coating exceeding-10 dB is larger than 7.5GHz, and the absorption peak value reaches-30 dB.

Detailed Description

The invention is further illustrated below:

the invention relates to a water-whitening-resistant water-based wave-absorbing coating which comprises the following components in percentage by weight:

water: 10% -15%, acrylate monomer mixture: 25.0% -35.0%, water-soluble initiator: 3.0% -5.0%, emulsifier: 2.0% -4.0%, pH regulator: 0.1% -0.5%, electromagnetic wave absorber: 45.0% -55.0%, water-soluble defoaming agent: 0.1% -0.5%, water-soluble leveling agent: 0.5% -1.0%, water-soluble anti-settling agent: 0.5% -1.0%, water-soluble dispersant: 0.5 to 1.0 percent.

The acrylic ester monomer mixture comprises a hard monomer, a soft elastomer and a functional monomer; the hard monomer is one or more of methyl methacrylate, styrene, acrylonitrile and methyl acrylate; the soft monomer is one or more of isooctyl acrylate, ethyl acrylate and butyl acrylate; the functional monomer is one or more of acrylic acid, hydroxyethyl acrylate, hydroxypropyl methacrylate and glycidyl methacrylate.

The water-soluble initiator is one or more of ammonium persulfate, potassium persulfate and azo initiator VA 044; the emulsifier is one or more of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, Cyanote EF-800 emulsifier, CO-436 emulsifier, CO-897 emulsifier and CW-3008 emulsifier; the pH regulator is one of ammonia water and sodium hydroxide aqueous solution; the electromagnetic wave absorbent is one or more of barium titanate, silicon carbide, carbon black, polyaniline, single-walled carbon nanotube, graphene and ferrite; the water-soluble defoaming agent is one or more of Gaoka CK-C5001, CK-M026, Nanhui CI-1104, Tiande DJ-1327, Delong DF-3224, Pasf A38 and national DU-077; the water-soluble leveling agent is one or more of BYK-381, BYK-346, BYK-333, Silok-355, Qingtian DH-4310 and Rohm Haas 2020 NPR; the water-soluble anti-settling agent is one or more of Kogyang KYC-426, Qingtian DH-6900, Jinyuan 2654623 and Lisheng FC-7155W; the water-soluble dispersant is one or more of Silok-7155W, Qingtian DH-6000, Hensk H-791 and Lida chemical LD-64192.

The invention relates to a preparation method of a water-whitening-resistant water-based wave-absorbing coating, which comprises the following steps:

1) according to the weight percentage of water: 10% -15%, acrylate monomer mixture: 25.0% -35.0%, water-soluble initiator: 3.0% -5.0%, emulsifier: 2.0% -4.0%, pH regulator: 0.1% -0.5%, electromagnetic wave absorber: 45.0% -55.0%, water-soluble defoaming agent: 0.1% -0.5%, water-soluble leveling agent: 0.5% -1.0%, water-soluble anti-settling agent: 0.5% -1.0%, water-soluble dispersant: weighing 0.5-1.0% of each component for later use, taking out 10% of the total amount of the acrylate monomer mixture into a flask, and adding all water;

2) adding all the emulsifier into the flask in the step 1);

3) preparing a water-soluble initiator into an initiator aqueous solution with the concentration of 1%, taking out 1/3, adding the initiator aqueous solution into the flask obtained in the step 1), heating the initiator aqueous solution in a water bath to 70 ℃, and initiating polymerization at a fixed stirring speed to generate a seed emulsion;

4) dropwise adding the rest acrylate monomer mixture and an initiator aqueous solution into the seed emulsion obtained in the step 3) at a constant speed, and continuously initiating polymerization at 80 ℃ until the polymerization is complete;

5) keeping the temperature of the polymerized emulsion in the step 4) for 1-2h, naturally cooling to room temperature, filtering and discharging, and adjusting the pH of the emulsion to be neutral by adopting a pH regulator to obtain the water whitening resistant polyacrylate emulsion;

6) adding the electromagnetic wave absorbent, the water-soluble defoaming agent, the water-soluble leveling agent, the water-soluble anti-settling agent and the water-soluble dispersing agent into the water-whitening resistant polyacrylate emulsion prepared in the step 5) to obtain the water-whitening resistant water-based wave-absorbing coating.