In the lighting industry, LED has been widely used as an energy-saving and environmentally-friendly green light source product. Compared with traditional light sources, LEDs must save more than 80% energy under the same lighting effect.
However, each LED is an independent point light source, and the luminous intensity is high. The LED lighting fixtures in which a plurality of point light sources are densely combined may form a problem of uneven light and glare, and the light diffusion material is born.
1 using frosted glass;
2 materials plus color powder;
3 material surface treatment, plus sanding, ribs.
All three methods have low light transmittance and the glass is fragile, and the latter two methods can see the point source.
Light diffusing material
(a material that transmits light and scatters light)
The point-like and linear light source can be converted into a planar light source, which has a large scattering range, good light transmittance, and uniform light distribution.
Two important indicators for evaluating the properties of a light diffusing material are light transmittance and haze. The former represents the transparency of a material, while the latter represents the ability of a material to scatter light. Light diffusing materials must have both high light transmittance and high haze.
At present, the mainstream light diffusion materials on the market can be prepared by a polymerization method and a blend modification method. Commonly used light scattering material substrates mainly use transparent polymers such as PC, PS, PET, PMMA and the like. PC materials are widely used for their excellent comprehensive properties such as high transparency, high toughness and high flame retardancy.
Generally there are polymerization methods and blending modification methods.
The polymerization method is based on the principle of light refraction, and selects two polymer monomers having a certain difference in refractive index and poor compatibility to co-polymerize or adopts segmental polymerization to further prepare a light-scattering light-diffusing material.
Two kinds of monomers with different reactivity are prepared by polymerization, because the scatterer monomer has different reactivity with the matrix-forming monomer, and the scatterer monomer is self-polymerized or copolymerized with the matrix monomer, such two monomers The optical properties of the agglomerated core formed in the respective polymer chains are uniform, and the light at the boundary of the agglomerated core is reflected and refracted, thereby forming scattering.
The polymerization method is widely used in the preparation of PMMA-based light diffusing materials.
The blending modification method is to add a light diffusing agent to the resin, the light diffusing agent is spherical, uniformly dispersed in the transparent resin to form a sea-island structure, and the light is similar to the specular reflection on the surface of the light diffusing agent due to the different refractive indices of the resin and the light diffusing agent. After multiple reflections, the light diffusion effect is achieved.
At the same time, the amount of light diffusing agent added, particle size and distribution, and refractive index determine the optical properties of the material.
At present, many light-diffusing materials are generally produced by this method, because this method is similar to polymer doping, and the process is simple, especially in the case of a very large amount of light-diffusing sheet, which can be continuously produced, and the production efficiency is high. high.
Light diffusing agent
According to the composition, it can be divided into organic diffusing agent and inorganic diffusing agent.
Currently the most widely used are acrylic and silicone light diffusing agents.
The optical performance requirements and main technical indicators of commonly used light diffusing materials are:
(1) It has high light transmission, high diffusion, no glare, no light and shadow;
(2) The light source is better concealed (effectively adjust the diffusivity and light transmittance, and the light transmittance reaches the maximum without seeing the lamp bead);
(3) Good fluidity, good mold release properties, and excellent weatherability;
(4) The light transmittance reaches or exceeds 80%;
(5) High flame retardancy;
(6) has high impact strength;
(7) Suitable for use with LED shades, bulbs, and tubes.
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