Topic 04 · Televisions and Smart Terminals (Brown Goods)

1. What makes brown-goods plastic parts special

1.1 Long-term indoor light exposure ≠ no aging

Many people believe "indoor parts do not need light stabilizers" - a widespread misconception. TV back covers and stands often sit right against the display module and power board, in a sustained local high-temperature environment of 40-60°C; at the same time, although the UV in household lighting is weaker than outdoors, the cumulative dose over an 8-10 year service life is not low.The coupled action of heat + light makes light-colored ABS back covers yellow noticeably within 3-5 years - for modern TVs sold on "maximum screen-to-body ratio", this is a fatal perception problem.

1.2 Flame retardancy is a hard threshold

TV back covers, power boxes, remote-control housings and similar parts generally require flame retardancy of V-1 or above. Unmodified ABS reaches only HB or V-2, dripping during combustion and possibly igniting the degreased cotton below.The back cover is a classic part under the triple constraint of "flame retardancy + weather resistance + light color".

1.3 Paint-free appearance is extremely shade-sensitive

High-end TVs and smart terminals widely use paint-free PC/ABS in metallic silver, pearlescent and matte space-gray finishes.The shade-control window for such systems is extremely narrow - initial shade differences from additives, shade drift during storage and interactions with pearlescent powder can all scrap whole batches of appearance parts. This is the first requirement brown-goods customers most often raise when selecting additives.

2. Brown-goods component conditions and risks

3. Tiangang's recommended formulations for brown goods

The following are starting points (by weight). Light-colored and paint-free systems need particular control of initial color; we recommend confirming shade difference on small samples first.

4. Key control points for brown-goods appearance consistency

4.1 Managing additive initial color

• Select proprietary low-color-development grades: the low color development and initial-color performance of proprietary grades such as HS-362, HS-962 and HS-330 are validated, suiting light-colored and pearlescent systems; HS-9611 and HS-200 are also rated for low color development and can be switched by substrate
• Fix the color base with a blended package first:The root cause of inter-batch shade differences is formulation fine-tuning. With pre-blended packages such as T-81 / T-70, the color base is fixed by Tiangang at the factory end - far more stable than fine-tuning the HALS-to-UV-A ratio batch by batch
• Add AO-427 to dyed systems: its dyeing-performance improvement directly improves masterbatch dispersion uniformity, with practical effect on shade control of light-colored parts
• Batch management: for light-colored appearance parts, we recommend agreeing with the additive supplier on inter-batch shade difference ΔE ≤ 0.5, and adding shade sampling to incoming inspection

4.2 Preventing frost (blooming)

The white haze on paint-free part surfaces mostly comes from surface migration of low-molecular-weight additives during processing or storage. Prevention points:① Prefer high-molecular-weight polymeric HALS;② Avoid extended residence at high temperature (barrel temperature not exceeding 250°C);③ Control additive-resin compatibility, adding a dispersant where necessary;④ Avoid high-temperature, high-humidity storage of finished products.

4.3 Special handling of pearlescent and metallic systems

Pearlescent powder, mica and metallic-effect masterbatches have large specific surface areas, physically adsorbing additive molecules, lowering local effective concentration. Countermeasures:increase the HALS loading by 20-30%, or switch to higher-molecular-weight grades that adsorb less on pigment surfaces; confirm the actual effect through joint shade and weather-resistance validation.

5. Recommended validation indicators