7 FAQs and Solutions for Light Diffusion Agent(Silicone Resin Powder)

As all to know high-brightness LEDs are intense-point sources of light that create bright spots of concentrated light. Known as LED hotspots, these bright spots can be harsh on the human eye. Therefore, in order to provide glare-free LED lighting, or to create wider viewing angles, designers often choose to diffuse the light emitted. This can be carried out by inserting thin films or sheets behind the lens, which not only help diffuse light transmission but also avoid unwanted glare. so this why light diffusion agent is more and more wildly used in LED filed.

There are many customers will often face a lot of different kinds of questions during their operations for light diffusion agent. here are some summarized 7 FAQs and solutions as follows, hope it can be helpful to you.

1. Light diffusion agent become gray and dark, color is not good

If it's a twin screw, please pay attention to avoid the plastic degradation caused by excessive shear gray, dark and color is bad as to be mistaken for the use of recycling material like twin screw distribution mixing, dispersion mixing which effect will be quite better than the single screw. so do not to use the long twin screw, If it's a single screw, please use a longer diameter or pin screw to make uniform mixing.

                  

2. Dust emission from light dispersant

If you have faced this problem, you can add some dimethyl silicone oil into light diffusion agent to solve it. Normally in plastic processing, white oil and other carbon chain dispersant oil, sometimes it will appear poor heat resistance and caused by black spots.   please kindly noted that amount of dimethyl silicone can make the surface of plastic particles getting wet, adding too much will easy to make a single screw slip material. what's more the viscosity of dimethyl silicone oil will decrease as the temperature increases. so generally, please use 500 viscosity in summer, 350 viscosity in whiter.

3. Snowflake spots appear in PC lampshade 

It because of most of PC materials are not dried, PC materials need to be baked at 120 degree for 4-5 hours before use, or use processing equipment with exhaust function.

4.PC lampshade become yellow  

When PC degradation or other substance are mixed, the processing temperature and the residence time of PC materials in the equipment can be adjusted, and attention should be paid to cleaning the equipment when the machine is newly started, and some antioxidants can be added to eliminate it if necessary.

5. Fluctuation of haze and light transmittance

The specific gravity of the light diffuser is higher than that of PC. If the concentration of the light diffuser in the masterbatch is too high and  the general weightless feeding device is used, the specific gravity gradient difference will be produced due to the vibration of the machine.  sometimes it will be normal at first, then the haze increases  and the light transmittance decreases, and finally the haze is insufficient. Therefore, the content of light diffuser in the masterbatch is generally no more than 10%.

6.Black dot problem  

It may be that the temperature resistance of light diffusion agent is not good enough. so it's recommend to switch to high temperature resistant light diffuser. 

7. Injection molding of optical diffuser PC

1.) Yellowing: 

The material stays in the barrel of the injection molding machine for a long time, the amount of glue injection is too large and the novice mold closing is not fast enough etc.

2.) Uneven color mixing: 

After blending masterbatch and transparent particles, the color mixing temperature is too low, the injection is too slow or the back pressure is low etc.

3.) Pattern sample: 

There is residue in the material passing through the machine.

4.) Water ripple: 

The temperature of the front mold is too low, the firing speed is too slow and the ejection position is too low.

                                

5.) Fog surface: 

Low temperature in the first section, slow firing speed in the first section and high back pressure.

6. Injection molding products have white spots and black spots: 

Carbonization of residual material in gun barrel, mixed with sundries, fracture of screw, metal powder falling, etc.

7. Foaming: 
Photo-dispersant decomposition, V-0 flame retardant decomposition, foaming KSS powder decomposition (temperature resistance is not enough).

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    linda@wanda-chemical.com