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SoRPlas Environmental Technology

Sony has developed a flame-retardant recycled plastic material by optimally blending leftover plastic from manufacturing sites with a proprietary sulfur-based flame-retardant also developed by Sony. Known as “SoRPlas” (“Sony Recycled Plastic”), what's special about this new plastic is that it contains a high concentration of recycled material. For some time, Sony has focused on developing new recycled plastics as material for use in digital still cameras and other products. By using SoRPlas in the bezel face of a series of BRAVIA LCD TVs launched in March 2011, Sony became the first manufacturer in the world to increase the concentration of recycled material in its manufactured products to 99%(*). Sony anticipates that it will be able to reduce CO2 emissions during the plastic manufacturing process (including transportation) by around 80% compared with earlier products made using virgin plastic and conventional flame-retardants (as of February 2011).

*While averages vary, recycled plastics in the market tend to contain between 10-30% recycled content, with the remaining portion made up of virgin materials.

Producing Plastic from Defective Optical Discs and Leftover Optical Film

Sony uses large quantities of flame-resistant polycarbonate (PC) resins to produce chassis and parts for various products, including LCD televisions. It also uses transparent PC resins to produce optical discs, such as CDs, DVDs, and BDs, and light diffusion film (optical film). Manufacturing sites for Sony's optical film produce recyclable material in the form of leftover film. Optical disc manufacturing operations generate defective discs, including those rejected during inspection processes. Leftover film can be simply crushed, but crushed defective discs must first undergo chemical treatment by specialized contractors to remove coatings. The resulting material can be reused as recovered transparent PC resin.
  • Waste Polycarbonate Resin from Manufacturing Operations
    Waste Polycarbonate (PC) Resin from Manufacturing Operations


Optimal Blend the Key to SoRPlas Development

The PC resin used in defective discs and leftover optical film is not flame-resistant and burns readily. There are also differences in the physical properties needed for Sony products. To obtain a plastic with the flame-resistance and appropriate physical properties required for LCD televisions, such as impact strength and moldability, it is necessary to blend the recovered PC resins with various other raw materials, such as flame-retardants. Sony has accumulated detailed data regarding physical outcomes when PC resins recovered from leftover optical film and defective optical discs are mixed with various additives. Using this data, Sony optimally blended PC resins recovered from its manufacturing sites with its independently-developed proprietary sulfur-based flame-retardant. The result was SoRPlas flame-resistant recycled plastic.
  • Development of SoRPlas by optimal blend
    Development of SoRPlas by optimal blend


Newly Developed Proprietary Sulfur-based Flame-retardant

The sulfur-based flame-retardant developed by Sony can convert PC resins into flame-retardant PC resins using less than one-tenth of the amount of additive required with conventional phosphorus-based and bromine-based flame-retardants. When fire is applied to PC resin containing this flame-retardant, the flame-retardant acts as a catalyst, speeding up PC resin decomposition. Carbon dioxide, a non-flammable gas, is also emitted, further suppressing combustion. At the same time, the propagation of combustion heat within the PC resin is impeded by the formation of bubbles. Additionally, a thin carbonized layer is formed on the surface of the PC resin at the point of contact with flame. This isolates the material from oxygen in the environment, ultimately preventing combustion. Thanks to these three processes—the emission of a non-flammable gas, the formation of a heat-resistant bubble layer, and the formation of a carbonized layer that isolates the material from the environment—PC resin can achieve a flame retardant state through the addition of an extremely minute quantity of flame-retardant
  • Flame-resistant Mechanisms of  PC resin with Sony’s Sulfur Based Flame-retardant
    Flame-resistant Mechanisms of PC resin with Sony's Sulfur Based Flame-retardant


Advantages of SoRPlas

The manufacturing processes for SoRPlas (including transportation) generates only one-fifth as much CO2 as the processes used with conventional virgin plastics (PC/ABS resins with phosphorus-based flame-retardants). This is because only a small amount of the newly developed flame-retardant needs to be added, with the result that SoRPlas contains a high concentration of recycled material. This means that the amount of petroleum-derived virgin plastic used can be drastically reduced. SoRPlas is also superior to existing virgin plastics in terms of recyclability, durability, heat-resistance and cost performance. Despite the fact that it is composed of 99% recycled material (with flame-retardant and pigments making up the remaining 1%), SoRPlas has such excellent color and luster that it can be used without painting after molding. This recycled and highly flame-resistant material has transformed the traditional image of recycled plastics.
  • Advantages of SoRPlas
    Advantages of SoRPlas


Looking Ahead

The SoRPlas developed this time was initially used as the material for Sony's 2011 LCD TV (BRAVIA) screen frames (or so-called “bezel”). Subsequently, SoRPlas was enhanced in terms of oil resistance and shock resistance---key requirements for use with mobile devices and from 2012 began being used in digital video cameras and digital still cameras as well. While PC resin is still widely used in the manufacture of many Sony products, Sony plans to develop different types of SoRPlas that meet the needs of products currently manufactured with PC resin.


Further information about this technology:

Press releases
http://www.sony.co.jp/SonyInfo/News/Press/201102/11-0208/

Scientific papers
Inagaki, Y., The Effect of Sulfonate Polymers on the Flame-Resistance of PC Resins (paper in Japanese presented at the 17th Polymer Materials Forum, 208, 2008)
 
Inagaki, Y., A Study of the Combustion Mechanisms of Metal Salt Polymer-Based Flame-Retardant Material (paper in Japanese in Polymer Preprints Japan, 57(2), 5333 (2008)

[IN ENGLISH]
URLs for Scientific conferences
The Society of Polymer Science, Japan





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