Compared with acrylic and polycarbonate glass application in strong LED tube in?

For shell and optical materials of traditional linear tube lighting alternatives are needed with the internal LED source as strong. In this paper, BILL MARSHALL explains the polycarbonate as LED tube provides a variety of advantages.

Fluorescent tube lighting has been prevalent in offices and factories and other commercial environment. Although this kind of lighting is effective, but now the trend is to replace the lamp, because the technology development to more advanced LED lighting. LED lighting is very ideal, because of its high efficiency, long service life. Replace the ordinary linear fluorescent lamp with LED tube, using solid-state lighting (SSL) technology provides the lumen power ratio in the design and optical challenges. In order to cope with this challenge, lighting manufacturers usually cooperate with suppliers, and the use of advanced materials to achieve the desired lens appearance, assembling method and optical properties. This gives them a competitive advantage in terms of performance and cost.

In this paper, we will discuss the use of polycarbonate in LED and other functions to describe the physical and optical properties as well as for LED lighting designers.

In order to produce LED tube material, need to consider some standard. Plastic has become the preferred material, especially polycarbonate, because it has unique characteristics and can provide multiple functions. The considerations include optical properties, mechanical properties, safety and design flexibility. All of these will be introduced in this paper.

optical performance

LED can be a one-way source very bright, manufacturers need the material or can make light directly through the surface irradiation to obtain maximum brightness, or provide uniform light distribution. LED manufacturers and designers all know, it is difficult to find a can hide the LED light and let the light to the best level of transmission material. This is not only important for aesthetics, but also to ensure the best energy efficiency.

Light cover LED source transmit or spread. Customers often find can provide high clarity and purity of the material, to ensure the best light transmission and maximum efficiency. However, the manufacturer is also concerned about the consistency of light distribution. Polycarbonate can be adjusted according to specific requirements, through the composite process to meet the specific requirements of the application. The transparent polycarbonate resin, light transmittance can reach more than 90%. In some cases, the light diffusion polycarbonate resin containing additives, usually with a specific geometry, particle size and refractive index of the polymer material, light transmission to help balance required and light diffusion. For the polycarbonate resin, can achieve excellent uniformity of light, while hiding the LED light source, thereby eliminating the "hot spot".

In order to achieve the best distribution of light, not only meet the supplier needs and meet the user expectations, before the start of LED lens or shell production, to test, in order to accurately quantify the light transmittance of polycarbonate resin and light diffusion rate. In determining the D50 angle (i.e., in which the number of transmitted light when the angle of 0 degrees is the number of transmitted light 50%), the use of variable angle photometer and direct light source measurement samples of different levels under different light diffusion agent effect. The developer according to the measured data of the diffusion of appropriate technology.

Figure 1: by measuring the relative transmittance (percentage) to assess the proliferation of LED pipe materials.

Adjust the performance is usually a careful balance, because the materials used for additive light diffusion can affect the efficiency of light transmission and light, and vice versa.

Mechanical properties

LED is a solid state device, there is no fragile parts or filaments, it is very strong. In addition, LED compared with the traditional light source, the service life is very long. Polycarbonate has excellent toughness, and is much better than that of acrylic glass, is used as an ideal material for lens, cover plate or shell, can make sure that the LED lamp or lamp is not damaged in the service life period.

Although the glass and acrylic resin respectively meet the requirements of LED lighting, as shown in Figure 2, but they are in shock and heat resistance and design flexibility is insufficient. On the contrary, polycarbonate and polycarbonate blends is increasingly recognized as an ideal starting point for the application of LED, because they have the necessary basic properties, and can be used with other monomers, polymers or additives tailored to meet the specific needs of performance.

Figure 2. compared to polypropylene and glass, polycarbonate in the main characteristics in the LED lighting tube.

UL (safety requirements)

LED pipe used not only for optical components, but also as a case. Due to the use of LED technology, the electronic components are placed in the interior, so need to comply with UL 94. The standard bulb is not so.

Ignition resistance or flame retardant requirements depend on the UL standard. High power LED light source temperature up to 80-110 DEG C. Polycarbonate resin provides excellent ignition resistance for these types of operating conditions. For low pressure applications require UL 94 HB and V-2 2 kinds of power supply requirements of combustible, polycarbonate, acrylic acid and styrene resin (e.g. styrene acrylonitrile SAN) can be considered as a lens, optical device and cover material. For LED lighting applications using 1 power demanding, optical device and lens materials required for the UL V-0, in some cases for UL 5VA. In order to ensure that the required fire resistance and compliance with UL 94 grade, the component must go through rigorous testing.

The test includes the use of blue flame, in order to achieve the desired level of combustible, at the appropriate time to sample exposure. The total combustion time, combustion and emission of combustion, droplet content level and the level of light cotton were measured according to the rating requirements. For UL 94 V-O certification, 1 mm thick sample