Topic 01: Additive Solutions for Air Conditioning and Refrigeration Appliances

Topic 01 · Air Conditioning and Refrigeration Appliances

Air conditioners have the highest plastics content of any appliance category - the plastic parts of a split AC account for more than 80% of its weight. They are also the category with the most extreme difference between "indoor" and "outdoor" service conditions: the indoor unit sits in a warm room, while the outdoor unit withstands sun and rain all year round. Tiangang provides the AC industry with a complete additive program graded by component.

Main substrates: PP / ABS / HIPS / PC-ABS / AS Key components: Outdoor unit housing / air deflector / panel / chassis / bracket Key indicators: QUV 2000-4000 h (outdoor parts)

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1. Service-condition map for AC plastic parts

The plastic parts of an AC serve in distinctly different environments, so no single formulation fits all. This is the first thing Tiangang does when serving AC customers: break the whole unit down into components and regroup them by exposure grade.

Component	Common substrate	Service conditions	Aging risks	Weather-resistance target
Outdoor unit housing / side panel	PP / ABS / AS	Year-round outdoors: sunlight + rain + temperature swings	Yellowing, powdering, gloss loss	UV 2000–4000 h
Outdoor grille / air deflector	PP / ABS	Outdoor + antistatic requirement	Yellowing, electrostatic dust pickup	UV 2000 h+
Indoor unit panel / housing	ABS / HIPS / PC-ABS	Long-term indoor light exposure + nearby high temperature	Shade difference, gloss loss	UV 1000–2000 h
Chassis / bracket	PP / glass-fiber reinforced	Load-bearing + outdoor + vibration	Stress cracking, embrittlement	UV 2000 h+
Internal tubing / connectors	PP / PA	Sustained thermal environment (near the compressor)	Thermo-oxidative aging, embrittlement	Focus on long-term thermal stability

Industry background: AC output declined year on year in 2026, but exports are structurally booming - from January to May, AC export value to the EU grew 43.2% year on year, Western European household AC export volume grew 9.7%, and portable AC export volume grew by more than 70%.Export models mainly go to Western Europe, the Middle East and South America - regions with strong UV and high heat and humidity - where weather-resistance grades are generally higher than for domestic models.

2. Three core challenges for AC components

Challenge 1: Long-term exposure of outdoor units - the respective weaknesses of PP and ABS

PP The main chain contains tertiary carbon atoms, which readily undergo hydroperoxide decomposition under UV exposure; it ages far faster than ABS and is the most "sun-fearing" material for outdoor AC parts. PP chain scission also lowers melt viscosity, bringing strength loss and dimensional change.

ABS is the opposite case: the butadiene phase itself is not aging-resistant, but its overall thermo-oxidative resistance is better than PP. Its weakness lies in yellowing - the hydroxyl groups generated by butadiene-phase oxidation turn the material yellow, while AC housings are mostly white or light-colored and extremely sensitive to yellowing.

So the protection strategy differs for the two substrates: PP focuses on "inhibiting the free-radical chain reaction", ABS on "suppressing yellowing + retaining gloss".

Challenge 2: Long-term shade control for indoor units

Modern AC panels widely use paint-free processes (metallic, pearlescent, matte). Such appearance parts are extremely sensitive to shade difference ΔE - the initial shade difference brought in by the additives themselves, and shade drift during storage, can directly scrap appearance parts. At the same time, surface migration of low-molecular-weight additives forms a white "frost" haze that destroys the paint-free appearance outright.

Challenge 3: The antistatic vs. weather-resistance conflict in deflectors and grilles

Deflectors and grilles need antistatic properties to avoid dust pickup, but most antistatic agents are weakly acidic or contain hydrophilic groups, which antagonize classic HALS; the hydrophilic groups can also accelerate moisture adsorption, affecting long-term weather resistance. This is a relatively hidden compatibility challenge among AC components.

3. Tiangang's recommended formulations for the AC industry

The formulations below are starting points (by weight), based on typical injection-molding processes. Exact loadings should be confirmed with Tiangang's technical center in light of wall thickness, color system and target indicators.

Formulation logic: Tiangang's main recommendation for AC is to use pre-blended additive packages straight out of the bag, rather than having customers compound general grades themselves. For outdoor parts use HS-362 (proprietary compounding, Mn>2000, large temperature margin) or HS-625 (low alkalinity, resists rain wash-off); for indoor paint-free appearance parts use T-81 (dedicated pre-blended package for modified materials, 50%±2.5% concentration, carrier MFI>10) or HS-6608 (designed specifically for PP/ABS modified pellets); when coexisting with acidic antistatic agents, switch to HS-300 (low-alkalinity type); for export models, overlay XT-8 (NOR structure, does not react with acids) to handle high-humidity acid rain.Proprietary

About the loadings in the formulation table: The table below gives effective loadings. When using additive packages, convert to the actual feed amount by the package concentration - e.g. T-81 at a nominal 50%±2.5%: for a target effective HALS loading of 0.5%, the actual feed is about 1.0%. Tiangang's technical center can give feed conversions directly from the customer's existing formulation, avoiding repeated trials.

Component / substrate	Tiangang recommendation	Effective loading	Why this one
Outdoor unit housing PP / ABS, light colors	HS-362 Blended light-stabilizer package	0.5% – 0.8%	Proprietary compounding system, Mn>2000, 10% weight loss above 350°C, softening 105-120°C; light stabilization and antioxidation are already synergistically formulated, customers no longer need to compound primary + secondary antioxidants themselves
Outdoor grille / air deflector PP + acidic antistatic agent	HS-300 High-molecular-weight low-alkalinity HALS or the T-78 blended package	HS-300 0.3% – 0.5% T-78 feed 0.6% - 1.0%	Low alkalinity is a hard requirement for coexisting with acidic antistatic agents.HS-300 is less alkaline than conventional HALS and significantly improves weather resistance at just 0.1-0.8%; T-78 is a pre-blended package, so customers do not need to solve compounding ratios themselves
Indoor unit panel Paint-free ABS / PC-ABS	T-81 Dedicated pre-blended package for modified materials, 50%±2.5%	Feed 0.6% - 1.0%	Carrier MFI>10, with a good rheological match to PP/ABS modified pellets; the formulation is fixed at the factory end, ready to use out of the bag, sparing paint-free parts the most troublesome blooming and shade-difference trial compounding
Chassis / bracket Glass-fiber reinforced PP	T-70 Blended additive package or HS-962	T-70 feed 0.6% - 0.9% HS-962 0.4% – 0.6%	High glass-fiber filler content tends to adsorb powdered additives, causing uneven dispersion; granular blended packages disperse better than powders - the direct reason for choosing granules over powder
Models exported to Europe All outdoor parts + acid-rain conditions	HS-362 + XT-8 Blended package + NOR compound	HS-362 0.6% XT-8 0.15% – 0.25%	XT-8 has an N-OR structure, does not react with acidic substances, is resistant to sulfur at 3000-7000 ppm and chlorine at ≤850 ppm; REACH / TSCA registration is complete, with full compliance documentation for export models.Can be used alone or compounded with HS-625
Portable / mobile air conditioners Frequent handling + outdoor	T-78 Blended additive package	Feed 0.6% - 1.0%	Handling impact and exposure are dual conditions, so the formulation must balance weather resistance and extraction resistance; T-78's pre-blended system covers both at once

Need a pure general-grade solution?If cost or existing supply-chain constraints require starting with general grades, we recommend HS-962 (light stabilizer 783) as the core - it is itself a blend of two high-molecular-weight HALS, suitable for both thick and thin products, with good water-extraction resistance and excellent value. If additional antioxidation is needed on top of this, add AO-1010 + AO-168.But we recommend going straight to an additive package: what it saves is not money, but trial-compounding hours and mass-production variability.

4. Key process points

4.1 Addition sequence and compatibility precautions

Resin + masterbatch / filler high-speed mix 2 min
Blended additive package (T-81 / T-78 / T-70 and other granular types), mix 3-4 min until fully melt-dispersed
Low-alkalinity HALS such as HS-300 (if added separately) last, then discharge immediately after mixing 3 min
AO-427 (optional for dyed systems) add together with the masterbatch; dyeing stability is achieved during the high-temperature mixing stage

Compatibility precautions: ① Acidic antistatic agents must be paired with a low-alkalinity solution (HS-300 / HS-330, or simply choose T-78, which already contains a low-alkalinity system);② Thioester antioxidants (DLTDP/DSTP) should not be used at excessive loadings; their acidic by-products weaken HALS activity;③ Flame-retardant systems should be disclosed to Tiangang in advance so we can match the NOR solution of FR-810A or XT-8 and avoid acidic antagonism;④ If an existing general-grade formulation must be retained, we recommend adding HS-962 as the core and letting the blending system handle compatibility.

4.2 Processing temperature and thermo-oxidative control

For ABS, the recommended injection barrel temperature is 210–240℃, avoiding extended residence above 260°C
For PP parts, 180–220℃; keep barrel residence time within 3 minutes where possible
When reusing regrind or edge trim multiple times, we recommend increasing the antioxidant by 30-50% to compensate for additive depletion from repeated thermal history

4.3 Key points for white and light-colored systems

White appliance housings are the touchstone of AC weather resistance. Key points:① Use rutile-type titanium dioxide; the photocatalytic activity of anatase-type TiO2 accelerates resin degradation;② Pair with low-molecular-weight HALS such as HS-450 to improve initial color;③ Avoid easily migrating grades such as UV-P. For metallic / pearlescent paint-free systems, watch pigment adsorption of HALS and increase the loading by 20-30% where necessary.

5. Recommended validation indicators

Indicator	Test standard	Outdoor parts, recommended	Indoor parts, recommended
Artificial accelerated aging	GB/T 16422.2 / ASTM G154 (QUV)	No significant powdering at 4000 h	No significant powdering at 2000 h
Shade difference (ΔE)	GB/T 11944 (ΔE)	ΔE ≤ 2.0	ΔE ≤ 1.5
Gloss retention	GB/T 8807 (60°)	≥ 80%	≥ 85%
Tensile / impact retention	GB/T 1040 / GB/T 1043	≥ 70%	≥ 75%
Surface powdering grade	GB/T 15595	≥ grade 4	≥ grade 4

Tiangang can provide: Starting-point formulation advice → pilot samples → QUV / xenon-arc accelerated aging validation (full reports on shade difference, gloss and mechanical retention) → mass-production formulation tracking. Accelerated aging data can be correlated against natural-exposure data from our two sites in Wanning, Hainan and Mohe, Heilongjiang.

Need a formulation assessment for your specific model?

Tell us your substrate, component type and target warranty period, and Tiangang's technical center will give preliminary advice within 1 working day.

Last Updated: 2026-10-20

Certifications

National High-Tech Enterprise
Vice Chairman Unit, China Plastics Processing Industry Association (CPPIA)
Vice Chairman Unit, Agricultural Plastics Branch, China Agricultural Plastics Application Technology Society
Member, Ageing Methods Subcommittee, National Technical Committee on Plastics (SAC/TC15/CS5)
Member, Society of the Plastics Industry (SPI), USA

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