Preparation And Properties Of New Hydrophilic And Anti-fog Functional Coating Materials

The surface of transparent materials often appears foggy,which will hinder people’s use and may bring safety hazards.Applying a high-performance anti-fog coating as a simple and quick solution has received more and more attention and is of great significance.This topic adopts the principle of hydrophilic and anti-fog,aiming at the defects of current anti-fog coatings,such as poor water resistance,low hardness,poor anti-fog effect,poor adhesion and wiping resistance,etc.Starting from three aspects:environment-friendly bio-based sulfonic acid-based waterborne polyurethane,dual-curing organic-inorganic composite superhydrophilic polyalkenoate,and single-layer and double-layer anti-reflection and anti-fog organic-inorganic composite coatings,a series of hydrophilic anti-fog coating.The performance of the anti-fog coating was characterized,and the actual anti-fog effect was investigated.The main research contents of this paper are as follows:The first part:Preparation of UV-curable bio-based isosorbide-modified sulfonic acid-based waterborne polyurethane hydrophilic anti-fog coating.Using isophorone diisocyanate,polycarbonate diol,pentaerythritol triacrylate,triethylamine and dimethylol butyric acid as the main raw materials,a self-made hydrophilic low polyurethane prepolymer containing sulfonic acid group was synthesized by polymer sulfonic acid diol（SO₃-2OH）.An environmentally friendly isosorbide was prepared by using bio-based isosorbide（IS）as post-chain extender alcohol-modified sulfonic acid-based waterborne polyurethane.The effects of different IS and SO₃-2OH contents on the properties of polyurethane and its coatings were investigated by ultraviolet（UV）curing.The results show that SO₃-2OH and IS can improve the hydrophilicity of polyurethane,the contact angle is reduced from 80°to 16.7°,the coating film has a good anti-fogging effect,but if the addition amount is too high,the water absorption rate will increase significantly and the water resistance will decrease.Due to the introduction of a benzene ring with strong absorption of ultraviolet rays and a group containing a rigid spiro ring structure,the light transmittance is significantly improved,and the light transmittance in the visible light region remains above 92%.In addition,the thermal stability,hardness and gel content of the coating film were improved,the change of tensile strength is to increase first and then decrease,and the elongation at break showed a trend of first decreasing and then increasing.Taking all aspects of performance into consideration,when the SO₃-2OH content is 20%and the IS content is 75%,the comprehensive performance of the coating（UV-SIWPU-20-75）is the best.The second part:Preparation of sulfonic acid-based silica sol and preparation and properties of dual-curing organic-inorganic composite superhydrophilic polyacrylate anti-fog coating.Choose from butyl acrylate,methyl methacrylate,hydroxyethyl methacrylate,isophorone diisocyanate,γ-（methacryloyloxy）propyltrimethoxysilane,2-acrylamide-2-methyl Propanesulfonic acid（AMPS）was used as the main raw material,and an isocyanate-containing unsaturated monomer was introduced by free radical polymerization to synthesize a polyacrylate resin that can realize dual curing of light and heat;Silica sols grafted with sulfonic acid groups on the surface were prepared by sol-gel method.The optimized formulation of modified silica sol was explored,and it was compounded with polyacrylate resin to prepare a dual-curing organic-inorganic composite superhydrophilic polyacrylate anti-fog coating.The effects of different AMPS and sulfonic acid-based silica sol contents on the properties of organic-inorganic composite coatings were investigated.The results show that the water contact angle decreases with the increase of AMPS and modified silica sol content,from 56.7°to 8.3°.With the increase of silica sol content,the RMS roughness increases from 0.221 nm to 0.382 nm,which will be beneficial to the rapid spreading of water droplets.Good anti-fog performance can be guaranteed under both hot and cold fog.When the AMPS content is 10%and the silica sol content is 60%,the water contact angle is 14.3°,the water absorption rate is 8.1%,the water resistance is good,and the adhesion is grade 0.The Tg of the uncured,thermally cured and light-thermal dual-cured coatings were 0.93°C,24.2°C,and 108.17°C,respectively,and the glass transition temperature of the dual-cured coatings was improved.The thermal stability,hardness and scratch resistance of the coating were improved with the increase of the silica sol content.The hardness is as high as 3H,and the water contact angle does not change significantly after 30 times of wiping.The third part:the preparation of hollow nano-silica and the preparation and properties of single-layer and double-layer anti-reflection and anti-fog organic-inorganic composite coatings.Hollow silica nanoparticles（HSi O₂）were prepared by Stober hydrolysis method using ethyl orthosilicate,polyacrylic acid and ammonia water as raw materials.The effects of the dosage of ammonia water,PAA,TEOS and stirring rate on the particle size and morphology of HSi O₂were explored.Titanium dioxide（Ti O₂）sol was prepared by sol-gel method,and the hydrophilic resin in Chapter 3 was used as the loading material to form a hydrophilic top layer with HSi O₂.Ti O₂sol and resin form a high-refractive-index bottom layer,and the two layers are chemically bonded by UV curing,and the optimal refractive index and thickness of the top layer and bottom layer are selected to meet the requirements of anti-reflection at a specific wavelength.The effects of different dosages of HSi O₂and Ti O₂sol on the properties of single-layer and double-layer coatings were investigated.The results show that:when the volume ratio of ammonia water and absolute ethanol is 1:20,the synthesized nanoparticles have a regular hollow structure,otherwise they will not have a hollow structure.The larger the amount of PAA,the larger the particle size of HSi O₂and the wider the distribution.Increasing the amount of TEOS increases the thickness of the shell,which affects the volume fraction and refractive index of the cavity;When the rotation speed is 350or 300 rpm,a regular spherical shape can be formed;The single-layer PM/HSi-5 coating has the lowest refractive index,which is 1.326,and the transmittance at 489 nm reaches97.08%.The refractive indices of the top and bottom layers of the PM/HSi/Ti-10 double-layer coating were 1.326 and 1.63,respectively.When the film thicknesses were 104 nm and 84 nm,respectively,the transmittance of the coating at 550 nm reached 99.02%.The effect of anti-reflection and anti-reflection.The micro-nano structure is formed in the hydrophilic top layer,and the roughness becomes larger.The PM/HSi-5 coating rapidly reduces the water contact angle to 2°within 0.3 s,which is superhydrophilic.It has good anti-fog performance on both glass and PC substrates,and has practical value.HSi O₂and Ti O₂can improve the thermal stability of the coating.The PM/HSi-4 coating showed less scratches after 100 wipes,but still maintained a good anti-fog effect.It does not affect the use of occasions with lower requirements such as motorcycle helmets;After 10 times of wear,the coating still maintains good integrity and has strong wear resistance.The hardness of the coating is as high as 4H,the water resistance is good,and a strong chemical bond is formed with the hydroxylated glass plate,and the adhesion is good.