| LED has many excellent properties, such as energy efficient, safe,environmentally friendly, pure light color, rich colors, etc. As the new lighting sourcein21st century, LED has been widely used in a variety of display lighting, roadlighting, landscape lighting and other fields. However, compared with the traditionalincandescent light source, LED has some shortcomings at the optical level, such asuneven lighting and dazzling, which have great impact on its application in the fieldof lighting. Consequently, there is a higher demand for PC as LED lampshade andthe light guide plate. Therefore, it is very desirable to develop the light-scatteringcoating material with good light-scattering and scratch-resistant performance on PC.In this paper, alcohol or water phase colloidal silica was modified withγ-Methacryloxypropyltrimethoxysilane and vinyltrimethylsilane by the sol-gelmethod. And then the solvent was replaced by the reactive diluent, getting thenanoparticles/reactive diluents dispersion as the hardening agent. The effects ofreaction conditions, type and ratio of the silane coupling agent and other factors onthe stability of the modified sol and the dispersion were studied. A high hardness,UV-curable organic-inorganic hybrid coating based on acrylic oligomers, reactivediluents and the hardening agent was prepared in order to improve the scratchresistance of PC substrate. The effects of type and ratio of organic and inorganiccomponents on the properties of coatings were studied. Based on this, thelight-scattering agent was dispersed in the hard coating materials at a high-speed,obtained a coating with light-scattering performance and scratch resistance. Theeffects of type, contents, particle size and particle size distribution of thelight-scattering agent on the properties of coatings were studied. The main results areas follows:（1） The effects of reaction conditions, type and ratio of the silane coupling agentand the reactive-diluent, content of SiO2on the stability of the modified silica sol and the dispersion were studied. The results showed that:①The optimum conditionsbased on the alcohol phase silica sol: the reaction temperature is50°C, the reactiontime is3h, the ratio of the silane coupling agent is nKH570/nVTMS=1:1, SiO2contentis20%-50%;②The optimum conditions based on the aqueous phase silica sol: thereaction temperature is50°C, the reaction time is3h, W（ethanol）/W（KH570+VTMS+SiO2）=3/1, pH=3.2, content of SiO2is20%-50%. The as-resulted SiO2/reactive-diluentdispersion is a transparent yellowish liquid with good stability, the gel time of whichis more than one year.（2） The effects of epoxy acrylic resins （621A-80, EB600）, polyurethane acrylicresins （611B-85, MD595B, MD5061B） and amino acrylic resin （SM6119） on theproperties of the coatings were studied. The results show that the adhesion ofMD595B on PC substrate is excellent, and MD595B has good compatibility withnanoparticles/reactive-diluent dispersion. When WMD595B/WHDDA=6:4, thecomprehensive performance of coatings is preferable.（3） The effects of Trimethylolpropane triacrylate （TMPTA）, Tripropylene glycoldiacrylate （TPGDA） and1,6-Hexanediol diacrylate （HDDA） on properties ofcoatings were investigated. The results showed that the coating with HDDA asreactive-diluent has good adhesion on PC substrate.（4） The effects of inorganic component on coating performance wereinvestigated, including the type and ratio of silane coupling agent and the content ofSiO2. The results show that the hard coating with good performance can be obtainedwhen the SiO2/HDDA dispersion with nKH570/nVTMS=1:1and n（KH570+VTMS+SiO2）/nSiO2=0.1is added to the above-mentioned organic component. Thepencil hardness of the as-prepared coating reaches to3H, and the adhesion reachesGrade0. The transmittance and hazeis90.3%and0.5%, respectively. Besides, thecoating has a flat morphology.（5） The effects of the content of different light-scattering agent including aninorganic light-scattering agent Nano-CaCO3, an organic silicon light-scattering agent KMP-590and six acrylic resin light-scattering agents （poly-dispersity series:MR-7HG, MR-10G, MR-20E30H; mono-dispersity series: MX-500, MX-1000,MX-2000） on coating performance were investigated. The results show that thetransmittance and haze of the coating is87.2%and65.5%, respectively, when thecontent of Nano-CaCO3reaches20%. When the content of KMP-590is20%, thelight-scattering performance of the coating gets better. Transmittance is88.8%, andhaze is89.4%. There is a strong upward trend in optical performance until thecontent of acrylic resin light-scattering agent exceeds35%.（6） The effects of the particle-size distribution of light-scattering agent on thelight diffusion properties of the coating were studied. The results show that thelight-scattering agent with single dispersion offers a high transmittance for coatings,and the light-scattering agent with poly-dispersion offers a high haze for coatings.（7） The effect of the morphology of light-scattering agent on coatingperformance was studied. The results show that the spherical light-scattering agentimproves the optical and mechanical properties of coatings better than the layeredlight-scattering agent.（8） The effect of SiO2/HDDA dispersion on coating performance was studied.The results show that the addition of SiO2/HDDA dispersion can increase theabrasion resistance of the coating effectively and improve the haze of the coating tosome extent.The results show that the coating with good light-diffusing and scratchresistance performance can be obtained when25%KMP-590is added to theabove-mentioned hard-coating materials. The pencil hardness of the as-preparedcoating reaches to4H, and the adhesion reaches Grade0. The transmittance andhazeis89.6%and90.0%, respectively. |
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